How Many Carbohydrates Do You Need?

A perennial question, argument and debate in the field of nutrition has to do with how many carbohydrates people should be eating. While the nutritional mainstream is still more or less advocating a large amount of daily carbohydrate (with fat being blamed for the health problems of the modern world), groups often considered at the ‘fringe’ of nutrition are adamant that carbohydrates are the source of all evil when it comes to health, obesity, etc. They advocate lowering carbohydrates and replacing them with dietary protein, fat or both.

This is a topic that I discussed in some detail in Carbohydrates and Fat Controversies Part 1 and Carbohydrate and Fat Controversies Part 2 and I’d recommend readers take a look at those for a slightly different look at the issue than what is discussed here.

Arguments over recommended carbohydrate intake have a long history and it doesn’t appear to be close to ending any time soon. Typical mainstream recommendations have carbohydrates contributing 50% or more of total calories while many low-carbohydrate advocates suggest far fewer (ranging from the 40% of the Zone diet to close to zero for ketogenic diets).

This article looks at the topic in detail. And while I originally wrote it quite a while back (some of you have probably seen it before), it was nice going over it with fine toothed comb for an update. While the majority of it stands up well over time, I was able to make some slight changes to the values, along with removing some original stuff that wasn’t really relevant. Enjoy.

Introduction

It’s safe to say that most carbohydrate recommendations that you will see are put in terms of percentages, you should be eating 45% of your calories as carbs, or 65% or whatever number is being used.

As I discussed in Diet Percentages: Part 2, I don’t like this method. Rather, putting nutrient recommendations in terms of grams per kilogram or per pound is generally more valid (with one exception I discuss below). The percentages are simply meaningless without knowing how many carbohydrates are being provided in terms of gram amounts.

In that context, a typical ketogenic/low-carbohydrate diet might contain 0.5 g/lb (~1 gram/kilogram) of carbohydrate. An average moderate carb diet (such as The Zone or Duchaine’s Isocaloric Diet) might contain 1 g/lb (~2 g/kg) of carbohydrate or slightly more.   A typical high-carbohydrate diet would, of course contain more than that (perhaps 2-3 g/lb or more).  Typical recommendations for endurance athletes are in the 3-4 g/lb (6-8 g/kg) range and carb-loading may require 5-8 g/lb (10-16 g/kg) of carbohydrate.

Still, whether you’re looking at carb recommendations in terms of percentages of g/lb (g/kg), there is still a huge discrepancy between different experts. Some recommend lots of carbs, some recommend medium amounts, some recommend almost none.

Who’s right? Well, I am. Because rather than giving some single carbohydrate recommendation (that can’t possibly take into account all possible situations), I look at the individual and their needs to decide how many carbohydrates should be consumed daily.

Which is what I’m going to look at in detail in this article. The punchline, of course is that I’ll end up concluding that how many carbohydrates someone needs (or should consume) daily depends on the same factors that affect other nutrient recommendations: goals, preferences, types and amounts of activity, and our old friend, genetic variation. By the end of the discussion, I’ll have set both minimum and maximum intake values depending on different conditions that might crop up. Let’s start with minimum amounts.

Are Carbohydrates Essential?

Despite oft-heard claims to the contrary, there is no actual physiological requirement for dietary carbohydrate. Even the RDA handbook acknowledges this, right before recommending that a prudent diet should contain a lot of carbohydrates.

To understand why carbs aren’t essential, I need to discuss the concept of an essential nutrient briefly. And, in brief, an essential nutrient is defined as:

  1. Any nutrient that is required for survival.
  2. Can’t be made by the body.

Quoting from my own Rapid Fat Loss Handbook:

The second criterion is the reason that dietary carbohydrate is not an essential nutrient: the body is able to make as much glucose as the brain and the few other tissues need on a day-to-day basis from other sources. I should mention that the body is not able to provide sufficient carbohydrate to fuel high intensity exercise such as sprinting or weight training and carbs might be considered essential for individuals who want to do that type of exercise. I’ll come back to exercise later in this article.

But from the standpoint of survival, the minimum amount of carbohydrates that are required in a diet is zero grams per day. The body can make what little it needs from other sources. What, you ask, are those other sources? Read on.

Where Does the Glucose that the Body Makes Come from?

When carbohydrates are restricted completely, the body still has a small requirement for glucose (although this decreases over time) and the body has to find something to make glucose out of. That something is lactate and pyruvate (produced from glucose metabolism), glycerol (from fat metabolism) and some amino acids. It’s the amino acid use that can be problematic since they have to come from somewhere.

Now, if no food is being consumed (e.g. total starvation), that somewhere is generally muscle tissue (the body will also break down liver proteins); the body will readily break down body protein to scavenge the amino acids it needs to produce glucose. In doing so, the muscle released alanine and glutamine (produced in the muscle from the breakdown of leucine and the branch chained amino acids, so you know) which can be converted to glucose in the liver. This process goes by the unwieldy name of gluconeogenesis which just means the production of new glucose.

Protein losses during total starvation are extremely high to start, gradually decreasing as the brain switches over to using ketones for fuel (this reduces the body’s glucose requirements which means less protein has to be broken down to make glucose). Even so, during complete starvation there is always some loss of body protein. Over long periods of time, this goes from harmful (because function is compromised from muscle loss) to downright fatal. Especially as folks get extremely lean and body protein breakdown increases.

In this context, an under-appreciated fact of liver and protein metabolism (but discussed in detail in The Protein Book) is that over half of all ingested amino acids are broken down in the liver in the first place. A good portion of those can be used to make glucose and this is especially true when carbohydrates are restricted.

Switching from starvation to dieting, this is fundamentally a big part of why protein requirements go up when folks are dieting, more of the ingested protein is being used in the liver to make glucose, meaning that more total protein has to be ingested to make sure there is sufficient amounts to support things like protein synthesis in skeletal muscle.

I don’t want to discuss this in detail here (since this article is about carbohydrates) but the topic is covered to some degree in nearly all of my books. My original Ketogenic Diet had a thorough examination of protein sparing on a diet and, of course The Protein Book discusses how protein requirements change during dieting in detail.

I’d also note that, as long as protein intake is sufficiently high (e.g. the diet is covering the increased breakdown of protein in the liver and elsewhere), the amount of carbohydrates which are truly required is still zero; this is the basis of my Rapid Fat Loss Handbook approach: eliminate all non-essential nutrients (including carbohydrates) and provide only those that are essential (in this case large amounts of high-quality protein and essential fatty acids) to generate the largest deficit and maximum fat loss per day.

But, let’s assume that you don’t just want to eat massive amounts of protein, how many carbohydrates are needed to limit (or prevent) protein loss on a diet?

How Many Carbohydrates Do I Need to Spare Protein Loss?

Early research into the topic of starvation and low-carbohydrate dieting found that as few as 15 grams of carbohydrates per day can limit nitrogen loss in the body. And raising carbohydrate intake to 50 grams per day severely limits the need for the body to use amino acids for gluoconeogenesis (which is why I suggested setting daily carbs on the low-carb days of The Ultimate Diet 2.0 at 50 grams).

This occurs via at least two mechanisms:

  1. The increased carb intake maintains blood glucose and insulin at a higher level (inhibiting cortisol release).
  2. The carbohydrate provides glucose for the brain, limiting the need to break down body protein.

Basically, in the context of dieting, dieters can either jack up dietary protein to cover the increased carbohydrate requirements of dieting or simply eat slightly more carbohydrates to provide them directly. Both have the same end-result. 15-50 grams per day limits the body’s need to break down protein and will allow protein requirements to be set lower than a diet providing essentially zero carbohydrates per day.

 

But What About Ketosis?

Since I’m going to use the term in just a second, I need to define what it means. When fatty acid burning is ramped up to high levels (as when carbohydrates are restricted), the body starts producing ketone bodies in the liver. As noted above, many tissues in the body can use ketones for fuel, basically they are an alternative energy source to glucose when it’s not available. When ketones build up in the bloodstream beyond a certain point, a condition called ketosis is said to develop. In contrast to the diabetic ketoacidosis (which occurs in poorly treated Type I diabetics), dietary ketosis is not dangerous and is an adaptation by the body to total starvation.

Many diets such as The Atkins Diet and other very low-carbohydrate diets are based around establishing ketosis for various reasons which are beyond the scope of this article. I only bring this up as most ketogenic diets set a carbohydrate intake level of roughly 30 grams per day (allowing some vegetables but little else) although I’ve never found support for that specific value.

I bring this up in the context of this article as many people start such diets with the specific goal of developing ketosis (again, for a variety of reasons). Since many books give the 30 g/day value for a ketogenic diet, folks get a little anxious about carb intakes that are higher than that.

However, strictly speaking, any diet with less than 100 g/day of carbohydrate will cause ketosis to develop to some degree (more ketones will be generated as carbs are lowered). I’d note that many ketogenic dieters use Ketostix to track ketosis, small sticks that measure urinary ketone levels. These are misleading for a number of reasons, not the least of which is that while ketosis (as defined by blood concentrations of ketones) may develop, urinary ketones don’t always show up, especially as carbs are raised to nearer the 100 g/day high end.

In any case, an intake of 15-50 grams per day of carbohydrate will still allow ketosis to develop and those ketogenic dieters attempting to ‘eat as few carbs as possible’ might want to consider that in the context of not only providing much needed food variety (at 50 g/day, even a small amount of fruit can often be fit in) but also in the context of the protein sparing issues I discussed above.

Getting to the point, although the physiological requirement for dietary carbohydrates is zero, we might set a practical minimum (in terms of preventing excessive body protein loss) at 50 grams per day. I’d note again that, within the context of The Rapid Fat Loss Handbook approach, carbs are limited to essentially trace amounts; however protein (which makes up the majority of the diet) is set high enough to limit muscle loss.

However, not everyone functions well in ketosis. They get brain fuzzed, lethargic and just generally feel awful. Even with weeks of being on a ketogenic diet, they never seem to adapt completely. That’s not a good recipe for long-term adherence to a diet or healthy functioning or training.

Tangentially, I’d note that this seems to be related to inherent levels of insulin sensitivity. Individuals with good insulin sensitivity, who typically run well on carbohydrates, tend to not do well on low-carbohydrate diets. In contrast, individuals with insulin resistance often do far better reducing carbohydrates and that often means going to ketogenic levels. Finally, some people seem to have the metabolic flexibility to do well with either diet. I address this issue in more detail in article Insulin Sensitivity and Fat Loss.

So what if people want to avoid ketosis? In general, assuming zero or very low levels of activity, an intake of 100-120 grams of carbohydrates per day will prevent the development of ketosis, just providing the brain with enough carbohydrates to function ‘normally’. So, for folks who want (or need) to just avoid ketosis, 100-120 grams per day will act as a practical limit. Again, this won’t quite work as a recommendation for people involved in high-intensity activity since not all of the incoming carbs will be available for the brain.

So, summing up mid-article, the absolute requirement for carbohydrates is zero grams per day. However, depending on protein intake, a practical minimum for carbs lies between 50 grams/day (if someone functions well in ketosis) to 100-120 grams per day (if they don’t function well in ketosis). Let me mention very specifically that I’m not suggesting those numbers are a recommended level, I’m simply using them to represent a practical minimum value.

As a final note, before addressing the issue of exercise, I want to note that the above values above don’t change significantly with body size (e.g. it’s one of the few places that an absolute number of carbs, rather than an amount set relative to bodyweight is appropriate). Most of the above discussion deals with the carbohydrate requirements of the brain which, for the most part, doesn’t change massively with body size. A 120 pound female and a 200 pound male have roughly similar carbohydrate requirements for their brains because brain size simply doesn’t differ that much between them.

The Impact of Exercise

So far I haven’t considered the impact of activity on all of this as this can affect daily carbohydrate requirements. I’d comment that all exercise is not the same and different types of activities will affect carbohydrate requirements very differently. The type, amount and intensity of activity will impact on carbohydrate requirements.

Typical low intensity aerobic/cardiovascular work doesn’t generally use a lot of carbohydrate. So if someone were only performing that type of activity (i.e. walking 3-5 times per week), there wouldn’t be any real need to increase carbohydrate intake over the above minimum. They might want to increase carbohydrates to higher levels than that (for various reasons) but, strictly speaking, they probably don’t need to.

The carbohydrate requirements for weight training actually aren’t that great. I did some rough calculations in The Ketogenic Diet and concluded that, for every 2 work sets (assuming a set length of 30-45 seconds) or so, you’ll need 5 grams of carbohydrates to replenish the glycogen used.

So if you did a workout containing 24 work sets, you’d only need about 60 extra grams (24 sets * 5 grams/2 sets = 60 grams) of carbohydrate to replace the glycogen used. So if you were starting at the bare minimum of 50 grams per day and were doing roughly 24 sets/workout, you’d need to consume an additional 60 grams (total 110 grams/day) to cover it. If you didn’t function well in ketosis and were starting at the 100-120 g/day, you’d increase to 160-180 g/day. I’d note that, for the average male lifter, this works out to about 1 g/lb or ~2 g/kg lean body mass carbohydrate per day

In this context, bodybuilding nutrition (much of which has been determined empirically over the years) has long recommended carbohydrate intakes ranging from 1 g/lb on fat loss diets to 3 g/lb for mass gains so we’re definitely in that range at this point. General recommendations for strength athletes by the nutrition mainstream are in the range of 5-7 g/kg or 2.2-3 g/lb so these values are all pretty consistent.

Higher intensity cardiovascular exercise is a little bit harder to pinpoint in terms of carbohydrate requirements and can vary pretty significantly depending on the intensities and volumes. A sprinter running 60m repeats isn’t using a lot of glycogen, a trained endurance athlete working near their lactate threshold for extended periods can deplete glycogen fairly completely in 1-2 hours. Even at lower intensities, the 2-6 hour sessions done by endurance athletes can completely deplete both muscle and liver glycogen stores on a daily basis.

Full skeletal muscle glycogen depletion for these athletes might represent 300-400 grams of total carbohydrate or more. For an average sized endurance athlete this might represent 3 g per pound or ~6 g/kg on a more or less daily basis. Under less extreme circumstances, carbohydrate requirements won’t be as high. And while current recommendations for endurance athletes are in the 7-10 g/kg (3-4.5 g/lb) range, studies show that most athletes consume closer to 5 g/kg (2.2 g/lb).

However, only the most highly trained athletes are going to be able to do that on a daily basis. Even with exercise, the average recreational trainee won’t have carb requirements near that level. Essentially, if competition athletes are getting sufficient carbohydrate intake at a level of ~5 g/kg (roughly 2 g/lb), I see little reason for the average individual to consume more or for people to recommend that they consume more.

I should note that the above sections assume that maintenance of muscle glycogen is the goal. Under some situations (generally fat loss), glycogen depletion, or maintenance of glycogen at a lowered level is the goal. This means that an athlete or dieter may deliberately under consume carbohydrates such that, over some time period, glycogen concentrations decline. In such a situation, where someone deliberately wanted to maintain muscle glycogen at lower levels, the above values would be too high since they are aimed at full glycogen repletion after heavy exercise.

Of course, there are also situations where dieters or athletes want to increase muscle glycogen levels far above normal; this will require higher carbohydrate intakes than the values above.

Is There a Maximal Level of Carbohydrate Intake?

Logically, a practical upper limit for carbohydrates intake would be a situation where they made up 100% of someone’s total energy intake. An average individual has a daily caloric intake in the realm of 14-16 cal/lb. Since carbs have 4 calories/gram, this would represent a maximum intake of roughly 4 grams/lb (8.8 g/kg). Of course, athletes involved in heavy training (who are burning far more calories than 14-16 cal/lb) have higher caloric (and hence carbohydrate requirements). But for the typical person at maintenance, a realistic upper limit would be ~4 g/lb and this would leave no room for either dietary protein or fat (without going over maintenance calories).

Of course, there are also situations where a dieter or athlete wants to super-compensate their muscle glycogen levels; that is load the skeletal muscle far above the levels which are normally maintained. This is often done by endurance athletes looking to improve performance and various cyclical diets (such as my Ultimate Diet 2.0) use glycogen compensation for anabolic (muscle building) purposes.

Generally speaking, to generate maximal levels of glycogen requires first depleting the skeletal muscle with the combination of heavy training and a low-carbohydrate diet. Given those conditions, carbohydrate intakes in the realm of 16 g/kg (a little over 7 grams/pound) of lean body mass can be tolerated over a 24 hour period. This probably represents a practical maximum for carbohydrate intake but it would only be achievable under this very specific situation.

Summing Up

So let’s sum up, looking at both practical minimum and maximum carbohydrate intakes under different circumstances. For illustrative purposes, after each of the g/lb recommendations, I’ll give an absolute number of carbohydrate, assuming an athlete with 160 pounds of lean body mass.

Circumstance Carbohydrate Requirement1 Grams for an athlete with 160 lbs. LBM
Physiological Requirement 0 g/day 0 g/day
PracticalMinimum to Avoid Muscle Breakdown2 50 g/day 50 g/day
Practical Minimum for Individuals Who Function Poorly In Ketosis3 100-120 g/day 100-120 g/day
Additional Amount to Sustain Low Intensity Exercise Minimal approaching zero Minimal approaching zero
Additional Amount Needed to Sustain Weight Training 5 g carbs. per 2 work sets4 5 g carbs. per 2 work sets4
Average Recommendations in Bodybuilding Nutrition 1-3 g/lb. 160-480 g/day
Average Recommendations by Mainstream Nutritionists 2-3 g/lb 320-480 g/day
Average Intake for Endurance Athletes 2 g/lb 320 g/day
Recommended Intake for Endurance Athletes 3-4.5 g/lb 480-720 g/day
Practical Maximum for Non-Carb Loading Individuals 4 g/lb 640 g/day
Maximal Intakes for Carb-Loading ~7 g/lb 1120 g/day

  1. All values are in g/lb. To convert to g/kg, multiply by 2.2.
  2. Note: If protein intake is sufficient, this amount of carbohydrate is not required.
  3. All values above this line assume no exercise and do not change significantly with body weight.
  4. Assumes a set length of 30-45 seconds.

Clearly the above represents a pretty drastic range of carbohydrate requirements, depending on the specifics. For a typical male with 160 pounds of lean body mass, daily carbohydrate intake could range from the physiological requirement of zero grams per day to a near maximum of 1120 g/day during a carb-load. Which makes it no wonder that people are confused.

Simply, the question “How Many Carbohydrates Do You Need?” has no singular answer. The goals of the person, the amount and type of activity, their individual needs (e.g. insulin sensitive vs. resistant, whether or not they function well in ketosis or not), their individual goals all determine how many carbs are ideal in the diet.

Comments

comments

79 thoughts on “How Many Carbohydrates Do You Need?

  1. I’m interested if you would recommend any specific types of carbs to consume if someone was to approach a low carb diet in the long term? I guess it doesn’t really matter, but I wonder if you would recommend only carbs like fruits, nuts, vegetables and stay away from products like pasta, bread, rice?

  2. If carbs are being severely limited, they should come from the most nutrient dense sources which are fruits and vegetables. Because while carbs aren’t essential and there are not nutrients in those foods which are required for life, there is endless data that the various phytonutrients/chemicals/etc. in those foods are extremely beneficial for human health.

    Depending on the kind of training being done, and the total daily carb intake, there is also sometimes room for faster acting carbs around high-intensity training.

    Lyle

  3. If I am trying to stick to 100 grams of carbs a day, do I only count the 100 grams of carbs that I consume or do I also include the 58% of the grams of protein that are converted to glucose?

  4. okay im an athlete so how many carbs do i need. i work out 5 days a wk at least 1.5 hrs and once a week for 5 hrs. but im also trying to loose weight

  5. The points covered here are hard to find elsewhere. Thanks.
    Suppose you are 160 lbs, have been exercising moderately (jogging 40 min/day) for 4 to 6 months and consuming less than 50 gr of carbohydrates per day (assuming fiber is not part of the carb count); if this is not enough to prevent protean (muscle) breakdown, how is the breakdown likely to manifest itself. What body changes might one notice?

  6. Paul

    As long as dietary protein was sufficient, protein loss would/should be minimal. If higher intensity activity (e.g. anything over lactate threshold) was to be done, carbs would have to be increased.

    Lyle

  7. Lyle please help!!!
    I love your work, did the ckd, ud 2.0

    I have a very low bf -8%(Measured in the hospital ) and hate the idea of carbs in human diet(I”ve become sort of paleo freak) I want to seriously bulk up now and do it without any carbs just high fat and protein, pleeaase tell me it is possible! I function well in ketosis but notice that my muscles are flat(glycogen depletion) still i have no problem progressing at the gym, but my weight has stopped.

  8. You’re never going to gain mass most effectively on a ketogenic diet. At least raise carbs to 120-150 g/day. Carbs are not some evil and even paleo man got carbs in his diet.

  9. thanks !

    Well this is going to be a challenge for me.
    What do you think of slow carb before like oats+whey pre-workout(steady energy during the performance)
    and bananas(or other high gi fruits)+whey after(glucose+fructose+protein to immidiately replenish glycogen stores, and fruits for the sake of phytonutrients/chemicals/etc. )

    this is like a tkd actually:)

  10. Is it safe to limit carbs to go into ketosis if you are a Type 1 diabetic (insulin-dependent)? I want to try a really low-carb diet to lose about 30 pounds, but it’s been difficult finding information and my doctor doesn’t recommend it. Thanks.

  11. Ketogenic diets tend to drastically affect insulin response and the concern would be making sure that you don’t get into runaway acidosis. Of course, that can occur on a carb-based diet as well. mainly it would mean a huge change to how you dosed your insulin but there is work on ketogenic diets and Type I diabetes. My first book “The Ketogenic Diet” at least mentions the issue although I didn’t delve into massive detail.

    Lyle

  12. Audra: I was an insulin dependent Type 2 diabetic, and did this just fine. I only occasionally need insulin now and that is if I stray from the Keto – diet. I would read Dr. Richard Bernstein’s Diabetes Solution, probably the best book out there for low carbing with diabetes. The author has almost no diabetic complications after 62 years of T1 diabetes, so he has a lot to say.

  13. I am a 39yr old 141# runner. I have been limiting carbs (30g or less) and trying to limit fat, as well. I have been eating lots and lots of protein (ckn breast, eggs, cheese). I run at a slow pace for 30-40 minutes 5 times a week. I have been dieting for about 6 weeks (lost 21# so far), but I just started my running back this week. I am having a tough time getting through the run – no energy. I don’t want to lose muscle. What is the best pre-run food to get me through the run, but keeping in mind I am really in the ‘diet mode.’ My boss suggested nuts or chocolate milk pre run. What do you think? and how many carbs do I need for a 30 minute run? Thanks so much.

  14. Kim,

    While you certainly don’t need many carbs for that short of a run, clearly you’re not performing well on near zero carbs. Something like chocolate milk pre-run might work although, due to the slow digesting aspect of milk protein, it might cause stomach upset(this is highly variable). You might try something easier like an apple about 30 minutes before or sip on a dilute carb drink (think Gatorade) to the tune of 15-20 grams in 500ml of water during the run.

    Lyle

  15. The Atkins diet is a joke… “carbs” are needed for energy requirements period… So I’m not buying the whole idea of decreasing your carb intake and increasing your protein intake while exercising.

  16. Harold

    As discussed thoroughly in this article, it all depends on what kind of exercise is being done. Very low carbs can support low intensity types of activity but tend to fail when it comes to higher intensity activity.

    Lyle

  17. Admin

    Doesn’t ATP energy fuel most if not all functional movements (especially when exercising at high intensities)? Such as: Explosive speed training, sprinting, heavy weight lifting? ATP is made from the conversion of glucose. In addition, I was lead to believe more fat is burned during aerobic activities because of the high demand for oxygen. I think your articles are extremely informative and I’ve even shared this particular article with my family and friends and got their perspectives. I’ve even shared it with a couple clients of mine (I’m a Fitness Trainer). There’s a great article in Prevention magazine about complex carbohydrates. http://www.prevention.com/cda/article/nature-s-fat-burning-breakthrough/296ca6b509787110VgnVCM20000012281eac____/news.voices/in.the.magazine/march.2008.issue According to Janine Higgins, PhD, nutrition research director for the University of Colorado’s Adult and Pediatric General Clinical Research Center, Mostly all carbs have what’s called “resistant starch” which is a dietary fiber that’s fermented in the large intestines and releases an acid called butyrate. This fatty acid will subsequently restrict the liver from using Carbs and use fat as energy fuel. This theory literally is a breakthrough however more scientific research has to be done so a definitive conclusion can be made.

  18. Obviously a controversial subject but I am sticking to my guns here and say that anyone who depends on Ketones for fuel is a fuel / fool. It’s like running your car on crappy gas. Eventually plugs become fouled, engine dirty etc.

    Glucose is THE PRIMARY source of fuel for the brain. It runs best on it. Period. In my experience and on those of my past clients and my mentor William Smith of Intrafitt —it has always been the most sensible, realistic pathway. Why would anyone want to break down proteins for glucose anyway? Bodies will rob whichever proteins are not needed at that moment. hemoglobin, hormones, collagen, actin/myosin (muscle), etc. Tough to “burn fat” when you could be robbing your body of fat burning proteins. Even if you are eating plenty of it. Kind of like filling a bucket with water that has a hole in it.

    Best,
    Robert

  19. ATP is the only fuel that can be used directly during any type of activity.

    How that ATP is produced depends on the duration and intensity of the activity and there are several distinct pathways that the body has to produce ATP. One of those is carbohydrate oxidation but fat oxidation produces ATP as well.

    Lyle

  20. Robert,

    What glucose needs to be produced in ketosis can easily come from dietary protein, the body needn’t break down body protein at all. In my experience, some people’s brains run BETTER on ketones. Others run like shit and should consume carbs. It depends on the person and I’ll leave it at that.

    Lyle

  21. I have been interested in reducing carbohydrates for the purpose of dental health. However, I doubt that I would get necessary vitamins and minerals required for survival without a certain level of carbohydrates. (assuming I was trying to get them from natural foods)

    Meat and proteins are much more expensive than carbohydrates per calorie. Sounds like a very expensive diet!

    A diet composed mainly of fats, seems very unhealthy from a cardiovascular point of view.

    It does not seem like a practical solution for most people to eat no carbohydrates, despite the fact that you might survive on it.

  22. The trainer/nutrition advisor I have been working with makes a distinction between carbs: type one (starches, i.e. oatmeal, rice, potatoes, etc.) and type two (the carbs found in veggies, i.e. broccoli, carrots, apples, etc.). What is your take on this; specifically, when you say “carbs” do you strictly mean carbohydrate count regardless of the source or should there be a distinction?

  23. Dani

    This article is dealing primarily with non-vegetable carbohydrates. It’s not quite that simple as the body actually does derive some calories from fibrous vegetables (~1-1.5 cal/g) but for most people, the majority of digestible carbs in the diet will come from starches.

    Lyle

  24. Hello,

    I am very interested in what you have to say. I have been following Paleo/Zone for about a six months and my clients are doing the same.

    Normally, they have pretty good success with it, but I’m running into some troubles of late.

    For instance, I have one client who keeps losing weight (about 12 lbs so far), but after 3 weeks, her body fat is still the same. She’s eating less than 30g carbs/day. She weighs 242 lbs. She eats anywhere from 10-30 g protein daily (quite a variation) and anywhere from 3 to 35 g of fat. Any ideas on how she can lose more fat?

    I also have a client who came to me thin. Now she’s down to 12% body fat, and she’s too lean. From what I’m reading, it seems that I should up her carbohydrates.

    All of my clients train anaerobically and aerobically.

  25. Great reading.

    I’m a type 2 diabetic. I went on a no carb diet of dairy (minus milk), meat, raw eggs, nuts and salad for 3 months. I lost a stone and a half before I began to feel unwell. In addition, my short term memory seems to have been trashed. I’ve increased carbs to around 100gms/day and do feel better. I’m not adding any weight but my memory is still bad. A big plus is that I hardly seem to be diabetic any more. Almost as though the freedom from carbs enabled my pancreas to recover (dunno).

    Will my memory come back or am I damaged for life ?

  26. I am still confused as to how many carbs I need to eat daily. I am 198 lbs. and have a goal weight of 150. I am female and 58 years of age. Also, if I eat a food that has 5 grams of carbs and 2 grams of fiber, am I allowed to subtract the 2 grams of fiber from the 5 grams of carbs for a total of 3 grams of carbs for that particular food?

  27. Mickie: As per the article, it depends on the situation. How much activity, insulin sensitivity all go into the determination of how many carbs a given person needs on a given day. An old rough guideline (esp. for fat loss dieting) is an intake of 1 g/lb bodyweight and that’s often a good starting point. Fiber was addressed in some detail in recent articles on the site (Look for Fiber – It’s Natures Broom).

  28. Hi there, I have a question as to glycogen depletion.
    The total glycogen store on average is 500g (400g in muscle and 100g in your liver)
    This is equivalent to 1600-2000kcals.
    If this is the case and at rest we burn nearly all fat how can I be in ketosis in 24hrs which
    I am. (zero carb intake and no exercise being 6 foot at 100kg with 30%bodyfat)
    If the brain uses around 100g a day and if at rest we burn pure fat, it should take 5 days
    for our body to deplete our 500g reserve.
    By the same token if we have 500g of glycogen to deplete and it should take 5 days.
    Why on a psmf do we need so much protein at the start when our glycogen level is high.

  29. Because developing ketosis has nothing to do with muscle glycogen. It has to do with liver glycogen status (and a couple of other things) and the liver only holds about 50 grams and will be at least partially depleted after an overnight fast (and mostly depleted by about day 2).

  30. “Despite the fact that there is no physiological requirement for carbohydrates in the human diet”

    I will have to disagree with that. Carbohydrates join the structure of the cell membranes, and they are used in the production of enzymes, neurotransmitters, and they make up part of nucleotides and hormones, showing structural function in the human body. they are not only sole energy suppliers.

  31. had to spam me twice, eh?

    I’ll repose from the other article:

    ***
    Unfortunately you’re wrong and need to look up the definition of an essential nutrient which is that

    a. it is required by the body for life
    b. It can NOT be made by the body

    The body can produce glucose from other substrates (lactate, pyruvate, alanine, leucine). Hence carbohydrates are not essential to come from the diet. Because carbs don’t meet criterion ‘b’ for being an essential nutrient.

  32. This article is full of misconceptions about carbohydrates. First off all, even the oxidation of fats burns off the flame of glycolysis. You need some source of carbohydrates periodically AT LEAST to burn fat. Most importantly, however, is the energy requirement of your brain. Your brain requires approximately 200 kcal per day of carbohydrate fuel. If you want to have your body “make carbohydrates,” then go for it: but your brain WILL suffer.

  33. Thank you for repeating many old ideas that are incorrect. The brain shifts to ketones (a fat derived fuel) and can run just fine in some people (others feel terrible). And you dont need carbs to burn fat. That’s a 30 year old idea that is also false. I’d suggest you get a physiology book published since 1970.

  34. Hello Lyle,

    I came to the conclusion that I am not insulin sensitive. And that I need to eliminate a lot of carbs, to minimize the fat gains in a bulk phase. I’ts too bad for me that I can’t avoid navel fat and love handles in a bulk with carbs. My calorie intake in a bulk with carbs isn’t that high, but I get fat anyway.

    Is it possible for me to lose fat and gain muscle at the same time, when I’m bulking on a low carb diet? I’ve used your guidelines, and it seems that my minimum intake would be 180g/day on an exercise day.

    Thanks for the article!

    Victor

  35. Hi – I really enjoyed reading this article. I practice a 5 day on, 2 day off “diet” where I eat 50 or less grams of carbohydrates during the on phase, and then simply follow a healthy, normal, low-er carbohydrate diet during the off. Switching it up helps keep food boredom and burnout away, plus lets me indulge a little bit so my cravings so don’t get the best of me.

    I also exercise regularly (vigorously) with both cardio and resistance exercises 6 days per week, at least one hour each day.

  36. Hello Lyle,

    I’ve read a few of your excerpts/interviews, and I truly appreciate your clear distinction between weight loss and fat loss. My dilemma is that I have decided to reduce my BF Percentage and I’m not sure which of you’re books/diet plans would be best in my case; body comp below:

    Height: 6′ 3”
    Weight: 208lbs
    BF % : 11.8% (*multi-point caliper test at health center, not sure of accuracy)
    4 Days/wk weight training (high reps)
    Competitive soccer 1Day/wk
    Average 2080 calories per day (Carb-Fat-Prot; 48%, 25%, 27%)

    Overall body type is fairly muscular so, I want to break the sub 10% BF barrier without losing much muscle mass. Which of your books would you suggest; Rapid Fat loss or UD2.0?

  37. Hello,
    The article and the feedback was great….. I have a question about what type nutriton my sister need based on her schedule below?

    1. What works: Low Carb
    ” ” Aerobic weight Training.
    2. Recommendation: Lean Proteins, Unprocessed rice, sugar, less white potatoes, fruit & vegetables. 5-6 small meals throughout the day less salt/sugar/carbs more weights. 6-8 hours sleep, eat within 1st hour upon awakening, eat last meal by 6 pm. Eat at least 3 hours before bed time.
    3. Average Daily Schedule: Up at 4 am; 50 minutes drive to work; work at 6 pm, busiest time at work 8 am – 1 pm; Work end 6 pm, 50 minutes drive home; Home at 7pm, sometimes cook dinner after 7 pm.
    Sincerely,
    Anthony

  38. I feel like you can eat whatever you want, you just have to outhustle your carb intake. Use more glycogen than you put in. If you want pizza, cookies, cakes, chips, donuts, cereal,and all other sweets and goodies…..you better be ready to do some serious sprints.

  39. Lyle, thanks for the article. I don’t see you mention here whether the carbohydrate intake numbers are meant to include or exclude indigestible carbs (fiber). Atkins famously excludes them from all carb numbers; are your numbers, rough as they are, intended to be used the same way?

  40. Hi Lyle, brilliant articles, same question as Evan, should we be excluding indigestible carbs as in atkins when calculating carb numbers? Thanks Danny

  41. In your example of 2 worksets requiring 5g of carbs for replenishment, how many carbs do you suppose are needed for heavy low rep sets? Say, 3-6 reps to failure of squats. I assume there would be a significant variation between squats and bicep curls. No? (LBM in the 190’s)
    Also, if I required 60g of carbs to replenish glycogen used, is that the amount you recommend consuming if fat loss is the goal?(not trying to maintain ketosis just muscle)
    How about if mass gains are the goal?
    I’ve always wondered about this since carb recommendations for post workout are always so high with the phrase “don’t worry, its all going to the muscle”.
    Thanks

  42. Hi, I read your stuff and well, I think there are to many holes in your plans, body type, lean mass, excersize, and just how the certian bodys handle carbs, I am a bodybuilder, and have played with my diet alot, and found that when I want to trim down for a contest, that I drop my fats and carbs, and it does great, but I know a friend of mine if they follow my diet, him being around the same condition as I am, well his body will eat up more muscle then fat, he finds if he cuts the carbs to a min, and keep the fat intake about his normal then hes able to drop his body fat, the big drop in carbs effects his train of thought and he feels like shit and cant do any kind of weight training, so every ones body is different, some burn better cutting fat and some burn better cutting proteins and some on carbs, every one needs to play with there diet and keep a good log of what they eat and how it effects there body fats/mass every week.

  43. And if you’d read more than the ONE article you’re replying to, you might see that I address all of those issues elsewhere on the site. Maybe start with Comparing the Diets series for starters. Because nobody is saying one size fits all.

  44. Thank you. I found the table especially beneficial to me. I know that carbohydrates should primarily come from fruit and vegetable sources.

    My question is, if I am to consume 100g carbohydrates in a day, could some of this number be made up from sweet potatoes. I know sweet potatoes are a starchy tuber but if you are staying on your figure, does it really matter if you’re consuming tubers? Or should it come solely from low carbohydrate vegetables and fruit advocated on the Paleo diet.

  45. I’m just wondering, I know that low carb, low calorie diets will cause the metabolic rate to slow down significantly. Looking at carbohydrates alone (assuming calories were set at maintenance), would a carb intake of around that 120 gram mark (assuming no exercise) prevent this slow down?

    Or would you recommend a higher carbohydrate intake to keep the metabolism functioning optimally?

    I just wasn’t sure if it was mostly low calorie diets that caused the problems and this could be offset by bringing calories up regardless of carb intake or if it was the specific carb intake also playing a role. Thanks.

  46. I just wanted to say a few things, I have yet to read other articles, which I will once I have ample sleep. I realize this topic is contraversial and many topics have changed over the years with how our body works.

    Anyways, I know you commented previously on how a gentlman “needed to read a physiology book dated after 1970”. Well I know that’s false: there are indeed text books in the past ten years that conclude that a minimum level of carbohydrate is needed for basic brain function. But I’m not arguing about our body needing it, I just wanted to point out your statement was false.

    Secondly, there are many studies on acidosis and weight loss. I’m not referring to DKA and understand the differences. Without finding peer reviewed articles yet on the topic, and the reading I have done, I have found that ‘extended periods of ketosis will cause acidosis’– do you have a time frame? I believe this is what a lot of the medical field has a hard time swallowing. As a nurse, and have worked in the ICU, I would say nearly 95% of those patients were in a state of acidosis, a lot metabolic acidosis or respiratory acidosis, and our bodies are amazing at compensating for this in a healthy state. What bothers me is hearing type I/ (and moreso bothersome type II) diabetics that recklessly try fad diets without consulting their doctors OR go against doctors advice by doing so. It may be stated somewhere in your articles, but I’d love to see you add something along the lines of “please see your doctor before starting any type of exercise or diet regime” as like you said, everyone is different and requirements differ. It scares me that people with multiple diagnoses will put themselves into a state of ketosis, and already are in acidosis due to a lung/heart disease (which many do have multiple diagnoses as a type II diabetic, generally speaking). It also scares me to think that people are taking bicarbonates to counteract this acidosis. There are many studies to support negative affects of long term use of bicarbonates, and I know very well that bicarbonate (just like the kidneys excrete) is only short term solotion for an initial problem that needs to be fixed. Long term acidosis damages all your body organs. On a side note, it is why soda pop is so terrible (even aside from the tremendous amounts of added sugar).

    We do know that having acidosis in our blood makes it more difficult for our body to function in general, and of course we need our body to function to live (if its not obvious to all) and of course to lose weight on a cellular level.

    It also scares me that you use the words starvation when you type about ketosis, because of course, its what it is. And personally, I agree with a few previous points (but are still willing to listen by reading journals, not anecdotal books, no offense). I think by being in ketosis for short term may be beneficial, but logically, I cannot accept starving my body and disrupting its processes. Its not all about burning sugar, there are a million other processes that run the show, and many we do not know of yet.

    Until I know more, and I’m always searching, I’ll do what I know best: do everything in moderation. Everything we put in our mouth is at a risk– even your own foot.

    Cheers 🙂 And yes, tomorrow I’ll do more reading, maybe by then I’ll have more to say!
    PS: do you have any information on medium chained fatty acids? Another topic that has been controversial 🙂
    Dana

  47. I’ve been on the keto diet for a week now and am not in ketosis yet according to the ketostix however, I was consuming alot of cashews for fat and didn’t realize that they have a lot of carbs and no fibre…

    Anyway, besides the cashews, I’m getting only 25 to a max of maybe 50 grams per day of carbs, eating about 100-150 grams of fat, and about 100 grams of protein, so my breakdown is about 75% fat calories, 20 % protein, and about 5% if that, from carbs…

    How long will it take me to get into Ketosis?? I’m so frustrated…I should be there by now, no? I work out 5 days a week with about 50/50 being high cardio and the rest moderate to low. I do about 45 min of weights and I take on some intense, very aerobic hikes.

    Any comments?

  48. Hi!

    Your article is fantastic! Thankyou…

    I am a 28 y/o recreational natural bodybuilder. I currently weigh 100kg and I have visible abs but a little soft towards the bottom of my abs (i.e not as lean as a competing bodybuilder).

    My aim is to increase my mass slightly over the next 2 months and then “cut up” for three months and get as lean as possible while maintaing muscle mass..

    I currently train with weights 4-5 times per week and do 45mins of intense cardio per week (soccer).

    I currently consume about 210 grams of protein per day, consisting of three main meals & 4 Whey Protein Concentrate shakes.

    With regards to carbs, I currently have a cup of oats for breakfast and a piece of fruit, a small amount of canned beans (100 grams approx) for lunch, 1 Ryvita biscuit in the afternoon, an apple in the afternoon and a small sized potato for dinner.

    I try to fill up of vegetables such as broccoli or salad at luch and dinner.

    My question is, how much can I reduce the carbs I currently consume (as per above diet), without losing muscle mass? How can I change my diet to get lean as possible whilst maintaining muscle mass? I plan to perhaps increase my cardio to 3-4 20 minute sessions of running if neccessary and do 3 weight training sessions a week during the 3 month ‘cut up’ phase

    Kind regards,

    Luke

  49. From my own experience 100g carbohydrates a day is to much to enter ketosis.
    The ideal amount of carbohydrates was between 10-30grams, this sounds
    very little for most of you and i agree, but after a week or two your body will get adapted to the low carbohydrate intake and will start functioning normal… ofcourse some carbohydrate load days should be included every week or two just to ‘refuel’ your body.

    Regards,
    Kevin

    http://fit-free.blogspot.com/

  50. Hey, great article and thanks for such a thorough description, I wondered if anyone could give me some advice on my own situation.

    I’ve been dieting for three months, consuming about 500-600 calories a day, and cut out all carbs, apart from those found within vegetables, a small cup of branflakes, and about 15g of carbs in the soup I drink. I’m worried that this will damage my muscle, and wondered whether it would be a good idea to start protein shakes? I don’t weight train but I am currently meeting my goal of walking three miles a day. I have sourced a very low calorie/carb, high protein shake and wondered if drinking one of those a day would prevent muscle breakdown sufficiently?

    Thanks very much

  51. i think this great but i have a question if your non stop working out everyday how any carbs would yu need to eat to get bigger

  52. How many grams of carbohydrates per pound of body weight are required to reduce/control blood sugar levels. I weigh about 250 lbs, walk briskly about 1 mile per day for exercise which somewhat limited due to arthritic knees.

    Most recommendations seem to be for a fixed grams/day based on activity level such as club-level training and elite-athlete level training, but it seems logical that body weight must somehow be part of this equation. Please advise.

    Thanks and best regards,

    NIKT

  53. Lyle, will you marry me? –You are so good at this and you’re one of a kind. You cover it all with such distinction and for everyone. You’re truly a lifesaver…Can’t thank you enough. I love all your articles and have (most of) your booklets.

  54. Good summary article of important information.

    Like anyone else, I’m always looking for a simple answer. But like most other “good advice”, your article ends up by concluding that the answer all depends.

    I guess I have to accept that there’s no alternative to experiencing your own body and monitoring how it responds to different diets and activity levels.

  55. Laugh out loud Dana, you really went for it girl !

    But in all honesty the author is correct and not false as you have stated. I can only hope that your lack of understanding doesn’t impact upon your work as a nurse, because the patients really deserve better. Still it’s easy to comprehend why the level of care in hospitals is in serious question these days with ill informed staff such as your good self.

  56. I recently started a keto diet about 3 days ago.

    I’m 32 and have mild narcolepsy and I heard that some people have had success managing this neurological disorder through ketosis. The theory is that fat is a more stable fuel for the brain, with less ups and downs. My father who has the same condotion, was prescribed powerful stimulants, including meds that containh GHB.I’d rather not go that route.

    Wish me luck

  57. xavier:
    If you are “non-stop working out every day” you are going to destroy your body. Lyle Mcdonald has already provided an outline for carbohydrate ‘requirements’ throughout this very article, of which you can specifically refer to prior and under the heading “Summing Up”.

  58. Love your information on carb requirements, but can you help me? I am 53 and a competitive cyclist. I only ride 2x a week due to work. But I ride 40-70 miles of hard intervals and muscle fatiguing pushes during those two rides. I have felt weak lately while I have trying to loose weight 175 to 165 to obtain a competitive edge. When and how many carbs should I be consuming? What about protein requirements and how much? thanks

  59. I am going to re start p90x (original one not 2) am nursing and have just started dabbling in the low carb thing. I need to lose 45 lbs to get back to pre baby (this is my second) I have been trying to keep my carbs at 20 but usually end up at 30/40. Not from sugars or starches, I get some when I drink my whey protein which I mix with light soy milk. I also include some sort of veggie, occasionally some berries or fruit. What do you recommend for my carbs? If you don’t mind I’d love your input.

  60. Excellent summary. Just started to take “carb reduction” seriously (though I knew about the Atkins Diets years ago and kind of toyed with adhering to it, now and then).

    Digging thru the net I found only a few sites that broke down the picture in terms of … TOTAL AMOUNT OF INGESTED CARBS DAILY.

    Everything else was on the order of “look at your plate and half of it should be vegetables” or “you should get about half of your daily calories from carbs”.

    And the Atkins “let’s keep carb intake as close to zero as possible for the induction phase” is (for me) just not practical. Having nothing but celery, arugula, 2 slabs of bacon, and 9 chicken breasts in my fridge doesn’t help at 11:00 p.m. when I want a snack before going to bed.

    I end up running out to the 7-11, getting a family-size bag of potato chips and a 1-liter bottle of Coke, and finish both off before going to bed. Bad, very bad.

    I wanted a break-down of how many carbs I could get away with … PER DAY … and then see how my everyday eating habits could be tweaked and adjusted so that “normal food” – – that’s already in the house and on the shelves at the local grocery store – – could be managed so that I wouldn’t have to do things like :

    (a) make my own salad dressing (it’s easy! just pull out your blender, get the avocado oil, blanche 4 cloves of garlic, get an egg and remove the white leaving only the yolk, put all into blender and blend until emulsified, pour onto salad substituting pork rinds for croutons … blah-blah-blah … having to run out to my car and go to the 7-11 to get pork rinds, then, another 10 minutes to make 4 tablespoons of salad dressing for my dry arugula, after working all day … NO WAY JOSE)

    OR …

    (b) have to order all the special low-carb Atkins products online (getting home and finding the “pink card” from the U.S. Postal Service … “your package will be held at the branch post office until 11/12/2013”)

    NOPE.

    Once you calculate the “desired daily carb intake” for your bodyweight and situation, then you can look around your kitchen cabinet and local grocery store and figure out what “normal everyday foods” … made in a quick, normal, everyday way not involving …

    blender / food-processor / MagicBullet blender / VitaMix blender-juicer / Atkins sesame-seed flour / pork rinds / heavy cream …

    can still fit into your into your daily schedule yet still keep you around 100 g carbs daily over 3 meals / snacks …

  61. Hi. I lost about 70 lbs in 2010 from using the concept of Jorge Cruises book The Belly Fat Diet. I basically used his principle of 15 sugar grams per day and about 120 ish carb grams per day along with spin class about 2-3 times a week and doubles tennis 2-3 times a week. Now 4 years later and married for the last 2 years and in full blown menopause I have gained about 15 lbs back. I must confess over the last 2 years I have been eating too much and doing less exercise. About a month ago I started my spin classes back anywhere from 2 to mostly 4 times a week and have tried to apply the 15 sugar/120 ish carb grams per day. I can not seem to lose these pounds or inches. I also must confess to cheating over the weekends with some high sugar foods but mostly am doing the same things I was doing 4 years ago. Do you think with the menopause I need to cut back even further on the carbs? I am 55 years old perfect health no drugs. 5′ 91/2″ at 170 lbs?

  62. Under Ketogenic diet, it is understood that an endurance athlete/Higher intensity cardiovascular exerciser must consume additional carbs including fast carbs during high intensity training since not all of the available restricted carbs will be available for the brain.

    On the other hand (and correct me if I’m wrong) you don’t regard weight lifting as much taxing as these activities. So what prevents the body from using ketones during weight lifting, sparing the limited glucose for the brain and eliminating the need to increase carb intake as detailed in this article by 60 calories for 24 sets? Thanks.

  63. Hi Lyle, in regards to the weight training burning roughly 5g of carbohydrates for every 2 work sets, could this expenditure also be used to calculate the amount of calories you would burn during the workout? In this case the 60g x 4 calories per carb would equal 240 calories burned?

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