In a previous article I discussed how a group of overweight Boston Cops lost fat and gained muscle at the same time. Another study has done something similar and showed how to lose fat and gain muscle while on a low-calorie diet. The upshot is that weight training and extra protein build muscle during fat loss.
When on a weight-loss (low-calorie) diet, dieters normally lose muscle. Rule of thumb is one-fourth to one-third of the lost weight is muscle. That’s a bad thing, as muscle loss leads to lower metabolism and ultimately higher mortality.
Muscle loss probably accounts for associations between weight loss and mortality being not always what you’d expect. For instance, in old age, a higher BMI may be protective, because at that stage of life, weight loss often means muscle loss.
Lifting weights while dieting is a good idea, as that will largely prevent muscle loss on a low-calorie diet.
But can you actually add lean mass (muscle) while losing fat? Yes, and one of the keys is getting enough protein.
The participants in the study were randomized to two groups. Average age was 23, average BMI 29.7, just short of obese.
One group ate a low-calorie diet — a 40% calorie deficit, which is a lot. The other group ate the same diet but took whey protein several times a day. Not a low-carbohydrate diet either — both groups averaged around 300 grams of carbs daily.
The first group averaged 1.2 grams of protein per kg bodyweight, which is quite respectable.
The second group averaged double that amount, 2.4 g/kg.
Both groups did resistance training twice a week, a conventional 3-set each exercise circuit training routine. They also did high-intensity interval training twice a week. In my judgment, that combination at 4 times a week is a tough exercise routine. Results below.
The groups lost equal amounts of body mass, but the high protein group lost more fat, and actually gained about 1 kg of muscle. The lower protein group did not lose any muscle, however.
As before in the study of Boston cops, these young men were quite out of shape. Virtually anything they did in the way of diet and exercise was bound to get them in better shape.
If you’re already in good shape, your results would be not quite as good. You’ve reached the area of diminishing returns.
But if you’re overweight and not doing weight training, you should start.
A few caveats about this study. One is that the men were provided all of their meals. At a 40% calorie deficit, this may be the only way to stick to such a diet for any length of time, especially a high-carb diet like this. I doubt I could do it.
Conventional low-calorie diets suffer from this defect, that overcoming hunger over more than a few days is difficult. Hunger always wins.
I think they should have cut the carbs way back. That would lead to better fat loss and less hunger.
This study is a modified test of “eat less, move more” method of weight loss. This certainly works in the short term, but appears to be ineffective in the long term. People have great difficulty in merely eating less. Changing what you eat is more important in my view.
The difference from “eat less move more” in which it’s superior is that the exercise was weight training, which builds muscle.
Aerobic exercise is ineffective for fat loss. Building muscle is effective, because metabolism goes up. You still need to change your diet though.
This study was an interesting proof of concept for the idea that adding extra protein as well as doing weight training, while dieting, leads to fat loss and muscle gain simultaneously.
Many trainers and coaches say that losing fat and gaining muscle at the same time cannot be done. Some of them even say that if you want to gain muscle, you can expect to gain a lot of fat too. This study shows that they’re wrong.
Some other studies have shown that gaining muscle doesn’t require nearly as much protein as in this study, with the amount of protein in the lower protein group, ~1.2 g/kg, being adequate. But that amount assumes a weight-maintenance diet, not a weight-loss diet.
Building muscle on a weight-loss diet requires more protein.