How to Lose Fat and Gain Muscle at the Same Time

Most people who work out, especially if that workout is lifting weights, do so for the effects on body composition. They either want to lose fat, or gain muscle, but the question always comes up: how to lose fat and gain muscle at the same time.

Many fitness experts even deny that it can be done, and given how difficult it is to change body composition, that is, after the newbie stage, I’ve wondered myself. However, there’s actually some proof that it can be done in a published paper: Effect of a Hypocaloric Diet, Increased Protein Intake and Resistance Training on Lean Mass Gains and Fat Mass Loss in Overweight Police Officers (ref, full paper).

Overweight Boston cops

The policemen – they were all men – in this study were out of shape, overweight, and between the ages of 28 and 40. They complained generally that they had been gaining weight and losing strength when compared to the years of their prime. Their average age was 34, and their average weight was 99 kg (218 pounds).

Importantly, their lifestyle was just crappy and conducive to ill health. Carbohydrates made up 60% of their calories, with nearly half of that being sugar, and 75% of them did not even meet the 0.8 g/kg RDA for protein; 70% of them ate 50% of their calories right before sleep, and they worked day, swing, and night shifts.

So, they had poor sleep habits, and it appears that their diets were largely filled with sugar- and carb-laden junk, with not even close to enough protein. No wonder they became overweight and were losing strength.

The researchers divided the men into three groups; all of them went on a low-calorie diet, nothing too drastic at 80% of projected calorie expenditure, about 2200 calories a day.

  1. Diet only: One group did nothing but diet, for 12 weeks.
  2. Diet + resistance training + whey protein: A second group did the diet, and also did 4 days a week of resistance training. The training sessions lasted about 30 minutes each, and were done with a trainer and on machines. In addition, this group took an extra 70 to 75 grams of protein daily in the form of two whey protein drinks.
  3. Diet + resistance training + casein protein. A third group was like the second, but instead of whey, they took 70 to 75 grams of casein protein.

The two extra-protein groups got their total protein intake up to 1.5 g/kg body weight daily, about double what they were used to consuming.

After 12 weeks, the diet-only group lost 2.5 kgs (5.5 pounds); all of this was fat, with no significant change in lean mass. Not really a very exciting result for 12 weeks of dieting.

The second group – diet + resistance training + whey protein, lost 4.2 kg fat and gained 2.0 kg of lean mass. Much better.

The third group – diet + resistance training + casein protein, lost 7 kg of fat, and gained 4 kg of lean mass. A great result.

So we see that it is possible to lose fat and gain muscle at the same time. A high protein diet, including protein supplementation, and weight training, can do this.


You knew there was going to be a “however”. The subjects were really fat and out of shape to begin with, averaging 27% body fat and 218 pounds. Obviously it’s a lot easier to get someone into decent shape when they start from a low base than it is to improve someone who already eats right and works out. If you lift weights regularly, eat a decent diet with enough protein and little in the way of refined carbohydrates, then it will be difficult to add 4 kgs (9 pounds) of muscle and lose a lot of fat in 12 weeks just by making a few changes, such as adding more protein and eating a hypocaloric diet.

Whey vs casein

Of interest here is that the group that took casein lost more fat and gained more muscle than the group that took whey. Researchers have studied whey far more than casein, and generally whey seems to have the better results, but that was not the case here.

The same authors had done a study on burn patients. Severe burns result in a highly catabolic state and these patients typically lose a lot of weight and a lot of muscle. Of two groups, one on a high calorie diet, and the other on the same diet but with 70 g/d of casein protein added, the casein group gained weight twice as fast and had better gains in muscle strength (ref).

Whey protein is high in BCAAs and leucine and causes a spike in these amino acids in the bloodstream shortly after taking it, and then a decline not long thereafter. (See graph at the top of this post.) Whey also has high levels of cysteine, the rate-limiting amino acid in glutathione production, so whey helps relieve low glutathione and oxidative stress. With casein there’s no spike, since it is a slow-digesting protein, but it stays in the system much longer. Neither is casein a rich source of cysteine.

For those of you who wish to try casein, a couple of caveats. Casein is probably somewhat pro-aging, since it increases IGF-1 levels – meat and whey do not, or at least not as much. Another caveat is that I’ve seen studies in which it’s recommended to take casein before bedtime, and lifters who do this do gain more muscle. But, it will also completely abolish normal overnight autophagy, so this is another way that casein could be pro-aging. I’m still very interested in gaining muscle, and I do take casein on occasion, but I want my autophagy to proceed normally and daily, so I won’t be taking it before sleep.

Bottom line: How to lose fat and gain muscle at the same time

Casein could be a very effective way to gain muscle and lose fat when combined with a low-calorie diet and resistance training. But if you’re anything but an out-of-shape newbie, don’t expect the kind of gains you see in this study. The study does show how it can be done however, and whether you’re really out of shape to begin with, or a seasoned fitness veteran, the principles remain the same.

PS: Check out my Supplements Buying Guide for Men.


Leave a Comment:

jrm says September 17, 2015

Any research on using collagen as a protein supplement? I am also curious if there is data on collagen vs. collagen hydrolysate since the former takes longer to absorb.

Ross says September 17, 2015

What forms of exercise PD? I couldn’t tell from the paper.

So, do you think this merely due to “longer-acting”, or also to different amino profile of the two hydrolysates?

    P. D. Mangan says September 18, 2015

    Hi Ross, this is from the paper: “A well-controlled progressive resistance training program was developed which included 4 days a week of weight training with rest days between each session. The weight training program was monitored by an experienced trainer, using Cybex calibrated machines, with the training focused on four different large muscle groups, one group on each of the four sessions. The routines took 30–35 min to complete, and the progress was documented by each participant and checked by the trainer after each session. After a week of training, a maximum effort was determined by the trainer for each participant. Maximum effort was defined as the maximum weight which could be lifted for 8–10 repetitions for a chest press, shoulder press, and leg extension. A maximum effort was also obtained after 4, 8 and 12 weeks. Aerobic exercises, e.g. jogging, were optional but had to be performed on days where weight training was not performed or after the weight training session.”

    As for the nature of the proteins, it was always my understanding that whey had a better profile, since it’s much higher in BCAAs, which stimulate protein synthesis. If that’s true, then in this case, it’s the long-lasting nature of the casein. The authors appear to believe it’s the AAs though.

ProudDaddy says September 18, 2015

The graph reminds me of the subject of the refractory nature of protein synthesis. Layne Norton has perhaps the most prominent paper on the subject. If he is right, to build muscle, one would want leucine levels to drop after a few hours and then increase again. When we are infused with constant amino acids, protein synthesis stops after a few hours and does not resume!

I am unable to find any quality confirmations or refutations of Norton’s work, so I shudder when I read broscience recommendations to keep a constant dietary supply of protein throughout the day and night.

You take on this would be most valuable, as always.

    P. D. Mangan says September 18, 2015

    Hi PD, you’re right about that. Pulsed boluses of whey work well to stimulate protein synthesis, one every few hours. Refraction sets in relatively quickly, say 3 hours as I recall, but it may require a relatively high level of leucine, ad it’s possible casein won’t do that (possible, not saying unlikely).

Rob says September 18, 2015

So the lesson seems to be, don’t take your whey all at once, spread it out if you want to avoid that spike.

Steve says September 21, 2015

What about cycling casein with whey? Taking casein only on training days and whey on other days. That might enable more hypertrophy while also allowing autophagy on non-training days.

Harpo says October 5, 2015

Why did the researchers not have a diet+resistance training group? That would have provided better context about the benefits of other supplementation.

FirkinRidiculous says November 12, 2015

“…take casein before bedtime, and lifters who do this do gain more muscle. But, it will also completely abolish normal overnight autophagy…”

Care to explain this?

    P. D. Mangan says November 12, 2015

    Autophagy is increased in the fasted state, with low insulin levels. Protein and carbohydrates abolish the process of autophagy. Casein especially will do so because it persists in the gut and allows a steady stream of amino acids into the bloodstream. Thus, take casein at night before bed, and your cells will not enter a state of autophagy. Normally, when one fasts overnight, by morning autophagy is going at a high level.

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Targeted lean mass gains - Rogue Health and Fitness says January 25, 2016

[…] It’s been shown that regular strength training combined with adequate protein intake can result in simultaneous fat loss …. […]

AJ says February 8, 2016

Interesting article.

Do you attribute this to newbie type recomp phenomenon?

You have written previous articles (which I agree with) about caloric restriction and aerobic exercise, for weight loss, and the concomitant muscle loss that goes with it (not to mention drop in BMR, TDEE) and the eventual plateau.

If the science is right, the only way to slowly recomp would be to gradually add lean mass, keeping all other factors (especially caloric intake) the same.

In my novice humble opinion, once your lean mass and BMR goes up, calories naturally increase too, so fat loss is not as noticeable, unless as above, calories are strictly controlled (not reduced).

    P. D. Mangan says February 8, 2016

    In the case of the overweight policemen, yes, I attribute their great success to being newbies with a lot of room for improvement.

How to Sustain Fat Loss - Rogue Health and Fitness says May 2, 2016

[…] into a diet and fitness regime, no muscle will be lost during weight loss. In fact, you can even lose fat and gain muscle at the same time. One group of subjects who used extra protein along with their diet and weightlifting routine, lost […]

mendo says June 20, 2016

I’ve use casein before and for someone like me, it exacerbated my acne, given that it’s mostly derived from lactose or rather, it’s nothing but lactose.

It’s a pain to mix and even with a blender, you need more liquid than recommended. I’ve read studies that you’re better off with whey and if you need a slow digesting protein, stick with greek yogurt.

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[…] 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 […]

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