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Comparing the Diets: Part 2

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In Comparing the Diets: Part 1, I made some introductory comments about the different primary approaches to dieting which are high-carbohydrate/low-fat, moderate carb/moderate fat, and low-carbohydrate/high-fat. I also defined my terms as to what I mean by high, moderate and low. In the next parts of this article series, I want to examine each of the three major dietary camps, along with their pros and cons so that I can provide recommendations on which diet might be the most appropriate for a given situation or individual.

A quick note on the percentage nutrient notation: as much as possible I tried to adhere to a format where the percentages represent percentages from protein/carbohydrates/fat in that order. So a notation of 30/60/10 means a diet where 30% of the calories are protein, 60% are carbs and 10% are fat.


While trends are beginning to show shifts, the high-carb/low-fat diet is arguably the de facto standard recommendation for both health, weight loss and athletic performance. At the same time, it’s becoming more common to criticize this diet on various grounds, blaming it for increasing obesity and health problems among the general public. You can read more about Carbohydrate and Fat Controversies elsewhere on the site.

Research is finding that, among certain populations, such a diet can do more harm than good. For examples, individuals with insulin resistance tend to get better health benefits from lowered carbohydrates.

Among more fringe diet groups, a diet based around high-carbs and low-fat has become an almost unspeakable evil. Claims that you can’t lose fat on high carbs or can’t get ripped, or whatever, are becoming more and more common.

Now, if you still think of me as the keto-guy you’re probably expecting me to shit all over this diet interpretation or take the fringe stance on it. With some qualifications, I’ll say up front that you’re wrong. The reality is that there are plenty of folks out there who have made high-carb/low-fat diets work and work well.

In fact, over the years it’s probably safe to say that most contest bodybuilders have gotten into shape on such a diet. Folks in the National Weight Control Registry (NWCR, which tracks successful dieters and their habits) reports most using some version of a high-carbohydrate diet (although more recent surveys have identified smaller groups succeeding in the long-term with low-carb diets).

It’d be absurd to dismiss it out of hand even if that’s what most people do.

At the same time, it’s probably safe to say that a lot of folks don’t do particularly well on such a diet, although it depends on a lot of interacting variables. The question is what differentiates the groups: why does such a diet work for some but not others? It’s easy and convenient to say that the drug use among top bodybuilders makes such a diet workable but this is too pat of an answer. Nor does it explain the NWCR folks. In my opinion, the answer is more complex.

Now, upfront I will say that I think a 30/60/10 diet is a little unbalanced to begin with. My main problem is that the dietary fat is too low. As I discussed in Comparing the Diets: Part 1 the technical definition of a low-fat diet is anything less than 30% and the actual government recommended high-carb/low-fat diet is actually closer to 15% protein, 45-50% carbs and 30% fat or thereabouts.

As you might imagine, I find this lacking in protein for body recomposition or optimal athletic performance even if it’s probably ok for the average person (even there recent research supports a benefit of higher protein intakes, approaching 25% for fat loss diets even in the non-athletic). Frankly, my ideal high-carb/low-fat diet would be in the realm of 25-40% protein, 50% carbs and 20-25% fat although, as I’ve discussed before, the percentages themselves are fairly meaningless.

The first problem that typically crops up is that people take a diet that should be ‘ok’ (either 30/60/10 or 15/45-50/30) and screw it up completely. The problem is primarily one of interpretation. It’s not uncommon to see dieters, especially women, turn a 30/60/10 diet into a 10/80/10 diet and they do it by overemphasizing high GI refined junk (the government and researchers thinks that folks are getting their carbs from unrefined grains but this is generally incorrect).

Endurance athletes, who tend to overemphasize carbohydrates frequently do the same thing: many, in my experience, are protein deficient (and studies are suggesting that very low fat intakes can hamper endurance performance). That takes a diet that was right on the edge of being imbalanced to begin with and screws it up even further.

I can track a majority of high-carb diet failures directly to such a mistake in interpretation. And, if you take someone from 10/80/10 to anything else and the results will look like magic. It’s not so much that the new approach is magical as the original approach was screwed up. Just about anything is better than something stupid.

Ignoring this major problem, let’s assume someone actually sets up a 30/60/10 diet more or less ‘correctly’ in terms of amounts. There can still be problems. The first is one of taste. A 10% fat diet is literally a non-fat diet and the small amounts of naturally occurring fats in non-fat foods tend to readily fill up the small fat allotment. Many people find such diets to be tasteless and bland which compromises adherence and research shows that moderate fat diets (discussed in Part 3 of this series) show better adherence than very low-fat diets.

Bodybuilders will just suck it up, of course; they are used to dieting with food that tastes like shit and a common statement is that ‘When I diet, I just make sure I don’t eat anything that tastes good.’ Typical macho crap. But the rest of humanity is unlikely to stick to a diet that they don’t find palatable.

With such an extremely low fat intake, there can also be problems with essential fatty acid intake which can be difficult to meet with so little of a fat intake. Even Dan Duchaine’s high-carb/low-fat diet required 8% essential fats for a total of nearly 18% total fat content (this changed a 30/60/10 diet to 30/52/18 which is damn close to my ideal anyhow).

There is a certain minimal fat requirement, if for no other reason than to ensure adequate absorption of fat-soluble vitamins. Extremely low-fat diets can cause their own set of health problems and this is clearly a place where lower isn’t better.

Another problem that crops up has to do with the types of carbohydrates being eaten. Researchers and other well-meaning types seem to assume that this is going to be the source of carbohydrates among the general public but this is generally not the case. Most of the athletes and bodybuilders who follow such a diet emphasize low GI, unrefined, high-fiber foods; in my experience, most of your typical dieters do not. It’s one thing to eat 60% of your total calories from carbohydrates when all the foods you’re eating have a GI that is extremely low.

As soon as you start making breads, pastas and other high GI foods a larger source of your total carbohydrates you run into a few problems. First is that the speed of digestion is fairly fast, a problem made worse by the low fat intake and generally low fiber intake of high GI food sources (and most peope don’t eat enough vegetables or fruit which would provide some much needed fiber). Along with that, the glycemic load (which is the Glycemic Index * the number of carbs eaten)) goes up fast meaning blood glucose can be all over the map. For folks with even moderate insulin resistance (see below) this causes all kinds of problems.

Along with that, most of the higher GI carbs can be surprisingly high in calories. So while 2 oz of uncooked pasta may only contain 40 some odd grams of carbohydrates and 200 calories, an average large bowl of past may easily contain two or three times that. This can easily amount to hundreds of calories. Bodybuilders and athletes are typically obsessive compulsive to begin with, and measure all their food intake; your average dieter is not. So where an athlete will know exactly how many calories they are getting from the pasta or rice, the average person will end up eating too many calories.

That’s ignoring all of the highly refined, high-carbohydrate low-fat foods that food companies brought to market (Snackwell’s anyone?). As above, researchers seem to think that most people are increasing their carbohydrate intake from moderately refined sources but that’s simply not the case in my experience.

As soon as people heard that fat was bad and carbs were good, and food companies rushed high GI non-fat carb foods to market, folks went crazy. Studies even found that, subconsciously, folks figured they could eat more when it was low-fat. Any benefit from lowering the fat content was more than compensated for.

Basically, very high carbohydrate intakes tend to work best when the source of those carbs are low on the GI. If you’re willing to eat almost nothing but low GI carbohydrates in the first place, a high-carb diet will probably work. If not…

Related to this issue is meal frequency. Bodybuilders and athletes eating high-carb diets spread out the carbohydrates over 6 or more meals meaning their total carbohydrate intake per meal isn’t actually that large. That, along with the low GI and high fiber intake minimizes problems with blood glucose swings and the resulting problems. Your average dieter, eating 3 large meals per day, with high GI carbohydrates and too little fiber will generally run into problems with such a high-carbohydrate intake.

Another related issue has to do with activity. Athletes who are burning a tremendous number of carbohydrate calories per day can tolerate/handle many more carbohydrates without problems than someone who is engaging in little to no activity (your average person). This is discussed in detail in How Many Carbohydrates Do You Need?

A bodybuilder or endurance athlete doing 2 hour workouts on a nearly daily basis may be able to tolerate (and may in fact need) such high carbohydrate intakes; someone walking briskly 30 minutes per day three times per week does not.

Related to the activity issue is that of insulin sensitivity. Insulin sensitivity refers to how well (or how poorly) tissues respond to insulin. With high insulin sensitivity, small amounts of insulin generate a large response. With poor insulin sensitivity (insulin resistance), the body has to produce more insulin to get tissues to respond. Recent research has shown a clear link between Insulin Sensitivity and Fat Loss in terms of what diet is optimal.

Individuals who are highly insulin sensitivity handle high carbohdyrate intakes to a better degree than folks with poor insulin sensitivity. I should mention, in this regards, that even folks with substandard insulin sensitivity can sometimes handle high-carbohydrate intakes when insulin sensitivity has been temporarily elevated (such as with glycogen depletion). This is relevant because certain dietary approaches (such as cyclical diets like my Ultimate Diet 2.0) use this ‘trick’: they elevate insulin sensitivity temporarily and then load in lots of carbohydrates before insulin sensitivity goes back to substandard levels.

So what determines insulin sensitivity? Well, there are a lot of factors. First, there’s a genetic component, activity affects it drastically (improving it), so does diet. Diets high in refined, high GI carbs tend to impair insulin sensitivity, so do diets high in saturated fats. Fish oils and unsaturated fats generally improve insulin sensitivity. A crucial determinant of insulin sensitivity is body fat percentage.

Obese individuals frequently become insulin resistant, which causes problems with carbohydrate intakes are excessive (moreso when they are high on the glycemic index). One of the main problems has to do with hunger and appetite. Under conditions of relative insulin resistance, a high carbohydrate intake (especially with very low fat intakes) tends to spike blood glucose levels, which spikes insulin, which crashes blood glucose.

This tends to cause rebound hunger, making calorie control nearly impossible. It also makes people feel crappy with alternating periods of high and low energy. Studies are finding that high-carbohydrate/low-fat diets, especially when the carbs are high on the GI, cause detrimental effects on various health parameters in insulin resistant individuals.

Additonally, some people seem to be carbohydrate ‘addicts’. While it’s debatable whether or not this is a true addiciton, many people find that eating carbohydrates makes them want to eat more carbohydrates. Whether this effect is hormonal or just a taste effect is debatable but it is real.

For such individuals, a high-carb/low-fat diet can cause problems in terms of calorie control. It’s all good and well to tell such people to suck it up, or that dieting is supposed to be a test of willpower, but any diet that makes people feel lethargic and hungry all the time (from crashing blood glucose or simply the ‘taste’ of carbs) is not likely to be followed for very long.

As a final issue, empirically, high-carbohydrate diets can cause problems with stubborn fat mobilzation. The mechanisms are discussed in a later chapter but folks with a lot of lower body fat can have problems getting extremely lean on high-carb diets unless they reduce the GI to very low levels. That means pretty much veggies and the few low GI starches. Women seem to crave carbohydrates more than men and sticking to such a diet can be a losing proposition.

Continued in Comparing the Diets Part 3.

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