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Muscle Loss While Dieting to Single Digit Body Fat Levels – Q&A

Question: My question is about what the maximum amount of fat that can be lost per week when someone is in single digit body fat percentage. I’ve heard it kicked around that once you start losing greater than 2 pounds or so per week that the ratio of fat to lean tissue loss starts to migrate towards the uglier side of things. However, this is presumably for people with higher body fat percentages not trainees who have been dieting for awhile to get to single digit body fat. My guess is that the hormonal and general homeostatic adaptations that occur during prolonged dieting and fat loss skew the muscle to fat loss ratio independent of any metabolic adaptation.

I realize that there are no hard and fast rules here, but do you have a figure kicking around that brain of yours that articulates what is the maximum amount of fat loss per week while maintaining a decent  fat/muscle loss ratio once someone has approached single digit body fat? I’m guessing it’s no where near 2 pounds at that point.

I’m at about 9% and I’m regularly hitting a 7,000 calorie deficit (Bodybugg) and I’m starting to see my strength levels go down regularly for the first time. It looks like I’m starting to lose a little muscle too but I’m not skilled enough with the calipers to know for sure. Obviously I need to cut back on the deficit and see how things go but it made this question pop in my head. Hope you can use it on your site sometime. Thanks for all your hard work and great info.

Answer: The short-answer, as always, is that it depends.  Now here’s the long answer.

First, the idea that 2 lbs/week is the maximum amount of weight/fat loss that should be achieved has been around for years but nobody seems to know where it comes from.  Certainly there’s no physiological reason for this to be a maximum and much larger rates of true weight/fat loss can be achieved with extreme deficits.

Anyone who has watched The Biggest Loser knows this to be true and even without that level of asininity, very large folks following a protein-sparing modified fast as per my Rapid Fat Loss Handbook have been measured at 1/2-2/3 pounds of fat loss PER DAY.  Which is 3.5+ pounds of fat per week.  Clearly 2 lbs/week is a bogus value in a physiological sense.

So where did 2 pounds come from?  I suspect it was mostly a behavioral/reality issue.  Assuming a value of 3,500 calories per pound fat loss (and I’d note that this value has some issues inherent to it discussed in The Energy Balance Equation), to lose even 2 pounds per week means a net deficit of 7,000 calories per week or 1,000 calories per day.

Which means either a lot of activity (a minimum of 2 hours for someone relatively untrained) or fairly large-scale caloric restriction.  Now, certainly this can be achieved with extreme diets but my guess is that the practicality of the 2 lb/week rule came out of this idea: for most people, a larger daily deficit isn’t realistic.  At the time it was also assumed that faster weight loss was associated with poorer long-term results but, as discussed in Is Rapid Fat Loss Right For You?,  depending on the specifics, the truth is actually exactly the opposite of that idea.

Of course, weight loss isn’t fat loss and the issue of muscle loss is a concern, I discuss this in detail in What Does Body Composition Mean? as well as elsewhere on the site.  Another issue regarding the 2 pound per week rule is muscle loss while dieting; this is (or at least should be) a concern and, certainly early studies found that bigger deficits caused greater muscle/lean body mass lost.  But there were at least two problems with this:

  1. The caloric intake was stupid low.
  2. There was no exercise, especially weight training, done.

Number 2 is of course important, while all types of activity will spare some muscle in beginners on a diet, weight training is probably the best overall approach.  And it simply wasn’t a part of mainstream weight loss approaches or research when most of the work was being done.

Even there, number 1 is probably the bigger issue here.  Even very obese individuals need a certain amount of dietary protein to prevent muscle loss and when you only feed someone 300 calories/day, even if 100% of it is protein (and most very low calories aren’t because they are set up stupidly), that’s a maximum of 80 grams of protein.  Which is usually too little.  And is also is why I set up the Rapid Fat Loss Handbook diet by protein intake and not by calories.

You have to meet protein requirements on any diet to limit muscle loss; when researchers started giving obese folks a minimum of 1.5 g/kg lean body mass of protein on a PSMF approach, muscle loss stopped.    For a 300 pound individual with 40% body fat, that’s a daily protein intake of 122 grams per day or a minimum of 500 calories.  With tagalong carbs and fats, total daily caloric intake will be higher. Simply, setting calories at 300/day won’t allow sufficient protein; yet many of the data points came from exactly those studies.

Of course, all of the above really applies mainly to overweight individuals; for what should be obvious reasons obesity researchers tend to not care about fat loss in lean individuals.   However, there was work done on changes in body composition, usually during starvation (and most of this was by Gilbert Forbes who literally spent 30 years writing about the topic) showing that one of the primary predictors of what was gained or lost during over- or under-feeding was initial body fat percentage (discussed in detail in Initial Body Fat and Body Composition Changes).

And, as per that article, as folks get leaner, for reasons discussed in detail in Calorie Partitioning Part 1 and Calorie Partitioning Part 2, muscle loss tends to increase.   Some early work suggested that, when you were lean, you’d lose roughly 1 pound of muscle for every 3 pounds total weight lost.  That is, up to 33% of your total weight loss might be muscle.

And with the idea that faster weight loss made muscle loss worse, suggestions to limit weekly weight loss to one pound per week when you got lean often were made.  Duchaine echoed this in the seminal Bodyopus and for a long time I suggested 1-1.5 lbs/week as the ‘sweet spot’ for weekly weight loss for leaner individuals.  It’s still not a bad value for moderate deficit diets, mind you, and I use that as the sweet-spot value in Adjusting the Diet.

But the 1-1.5 lb/week value isn’t an absolute, some can lose faster than this as lean people using my Rapid Fat Loss Handbook have shown.  True fat losses of 2-3 lbs/week in lean individuals is possible at least for short periods of time (one limitation of the RFL approach for lean people is that it should only be used for about 2 weeks straight before something less extreme is done).

So clearly it is possible to lose more than the stock-standard 1-1.5 lbs/week of true fat without muscle loss.  And understanding why and how means understanding why muscle loss tends to occur on a diet in the first place.

Arguably the biggest reason (and the one we have only limited ability to control) is  shifting hormones: falling leptin and testosterone, increases in cortisol, and a whole bunch of other (bad) stuff happen during dieting and most of these things become more pronounced the leaner you get.   Cyclical diets (like the Ultimate Diet 2.0) and strategies such as The Full Diet Break go a long way towards helping with those issues since the periods of high-caloric intake help to restore hormone levels back towards normal (they can’t ever restore them completely).

Of course, as noted in those articles, a big reason bodybuilders use so many drugs is to fix problems while dieting. With enough testosterone, thyroid meds, thermogenics, anti-cortisol compounds, appetite suppressants, etc. they can basically replace everything that the body isn’t making anymore.

An additional factor is that people’s ability to train intensely often goes down on a diet and maintaining the appropriate tension stimulus to keep muscle is key to avoiding muscle loss.  This is one of the reasons I find the whole idea of increasing volume and frequency of training on a diet half-assed; as discussed in Weight Training for Fat Loss Part 1 and Weight Training for Fat Loss part 2, people do better when they cut volume and frequency and focus on maintaining intensity.

Diets such as the Ultimate Diet 2.0 get around this by having the heaviest workout after carb-loading (so you can go heavy) and even basic cyclical ketogenic diets help with this.  Refeeds refill muscle glycogen and that allows people to go heavier in the weight room; strength isn’t a perfect proxy but if you’re keeping your weights up in the gym, you’re probably not losing muscle.

I actually think that training poorly is part of why guys like Dan Duchaine found that more than 1 lb/week fat loss was too much without props.  Training in the 80’s and even early 90’s while dieting was often done in a rather stupid fashion.  People trained too many days with too much volume and often dropped intensity too much because of it.  That alone allows muscle loss to occur.

Coaches who use lower volume and/or lower frequency but higher intensity training on a diet don’t see that level of muscle loss on a diet (if they see any at all). As noted, people on the Rapid Fat Loss Handbook diet don’t report muscle loss so long as they do the training (low volume/low frequency/high-intensity) in the book.

Excessive amounts of cardio contribute to this as well.  When you have drugs to spare muscle loss, 2-3 hours/day of cardio is fine and lets you eat more.  For naturals, while it’s sometimes necessary to go to 2 hours/day at the end of a diet (to offset a cratering metabolism), too much cardio just causes the muscles to fall off on a diet.  Especially when combined with a big deficit and inadequate protein.  But people did (and still do) nutty shit when they diet to get lean; excessive cardio is part of that.

Adequate protein is also a big issue.  For years I went with the stock standard 1 g/lb but on a diet this is probably insufficient.  As I discuss in detail in The Protein Book, 1.5 g/lb should probably be the minimum while dieting (certainly some people get away with less but this is highly individual).  On extreme approaches, more than that (2 g/lb) may be needed.

So bascially if you look at old-school dieting for lean individuals, it had some major flaws including

  1. Often (not always) inadequate protein.
  2. Stupid training.
  3. No use of refeeds or full diet breaks to reset hormones and allow better training to be done.

And while certainly many make the above work, just as many (if not more) have issues with strength and performance loss.

So what’s the answer to your question after all of that?  Well it depends.  If you insist on doing things badly, training too much, excessive cardio, inadequate protein, too stubborn to use refeeds and diet breaks, the old value of 1 lb/week may be exactly right with 1.5 lbs/week maybe being achievable.

Do things in what I consider the ‘right’ way (proper training, adequate protein, refeeds/full diet breaks used) and you can get faster fat loss per week without performance or muscle loss.  1.5 lbs/week is usually achievable for most and, for short periods, with extreme diets, more than that can be achieved without muscle loss.

Of course, there is still individuality in all of this probably relating to genetics and hormone levels.  Some people lose muscle more than others, they have to go with slower rates of fat loss even if they do everything ‘right’.  And others are lucky, they lose fat more easily (some of the reasons are discussed in The Stubborn Fat Solution).  But they tend not to be in the majority of trainees (they are usually in the majority of folks who get on stage).

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