Do Caloric Deficits Lead To Muscle Loss?

Do Caloric Deficits Lead To Muscle Loss?

In reviewing my upcoming book, Fat Loss for Everybody, Chris asked an important question. In fact, it was so important he said:


As far as I’m concerned this is the most critical point; the whole concept stands or falls on this.


It’s not easy to convince Chris’ skeptical mind… he has a rather good habit of requiring evidence, especially when it contradicts his current beliefs.

This means that either I’d stumbled upon a rare gem, or fool’s gold.

The statement I’d made in my book (and quite dismissively according to several reviewers), was:

Caloric restrictions do not cause muscle loss as long as you’re eating minimal amounts of protein and resistance training regularly.


For those that haven’t lived off a bodybuilder’s diet for years where you eat a small meal every 2-3 hours…
or set an alarm for the middle of the night so you can guzzle down your protein shake…
or sacrificed clean underwear and socks for protein bars in your backpack on a weekend hiking trip…
then the above statement may not be too shocking. Consider yourself fortunate as it’s quite miserable!

But for those of us who have spent years (or even decades!?) believing our muscle would waste away if we didn’t get protein every 3 hours… well, that’s just not the case.

Here are 3 solid sources for this argument:

1. Bryner RW. Effects of resistance training vs. Aerobic training combined with an 800 calorie liquid diet on lean body mass and resting metabolic rate. Journal of the American College of Nutrition 1999; 18(1): 115-121

2. Rice B, Janssen I, Hudson, R, Ross R. Effects of aerobic or resistance exercise and/or diet on glucose tolerance and plasma insulin levels in obese men. Diabetes Care 1999; 22: 684-691

3. Janssen I, et al. Effects of an energy-restrictive diet with or without exercise on abdominal fat, intermuscular fat, and metabolic risk factors in obese women. Diabetes Care 2002; 25:431-438

With a quick summary:

  1. After 12 weeks of an 800 calorie daily diet including 80g of protein per day and 3 sessions of weight training per week, men and women see no loss of muscle mass.
  2. After 16 weeks of a daily 1000 calorie deficit and 3 sessions of weight training per week, this male-only study showed no loss of muscle mass and over 20lbs of fat loss.
  3. After 16 weeks of a caloric deficit and 3 sessions of weight training per week, this female-only study showed no loss of muscle mass.

There are several other studies that conclude the same… if you’re convinced I should get off my lazy ass and list them as well, let me know in the comments and I just might make the effort!

So, in a few words; yes, it’s possible to keep muscle while in a caloric deficit as long as…

  1. You’re weight training 3 or more times per week
  2. You’re getting enough protein

However, a little speculation is still in order.

These populations were not massive, elite athletes. That being said, I suspect even very large individuals (like Chris) can still diet and keep their muscle mass as long as they continue their training and eat enough protein. Sure, energy levels will likely plummet… the bigger you are, the harder you fall. But protein and training really aren’t problem since big guys usually get a lot of both.

As for my results… you’ll have to wait and see… but I’ll be posting some measurements and vanity pics this summer!

Stay Tuned! :D