Resistance training is critical for weight loss

“Weight loss” is a misnomer: when people want to lose weight, it means they want to lose fat. Unfortunately, when fewer calories are consumed than expended, along with fat, muscle is lost as well. This is why resistance training is critical for weight loss.

Typically, one quarter to one third of the loss of body weight is comprised of muscle. This is to be avoided at all costs, since it lowers the metabolic rate, since muscle is a highly metabolically active tissue, and fat is not.

Furthermore, as I documented extensively in my book, Muscle Up, by virtue of being so metabolically active, muscle plays a large role in glucose uptake, and hence in insulin sensitivity. Good metabolic health requires at least normal muscle mass and healthy muscle tissue. Generally, a greater-than-normal muscle mass is even better for health. Health risk due to high body mass index is due solely to excess fat, not muscle.

Higher protein won’t help muscle loss during a diet

A recent study looked at the effect of a normal protein, low calorie diet versus a higher protein, low calorie diet, on overall weight loss and muscle loss. (1)

The subjects were all overweight, and all consumed diets restricted in calories by 25%, which is a considerable amount.

One group consumed normal protein at 0.9 grams per kilogram of body weight, and the other consumed high protein, at 1.7 grams per kilogram. The latter protein consumption is similar to what a bodybuilder might eat.

Results: both groups lost the same amount of weight, about 9 kg, and both groups lost the same amount of muscle, about 2 kg. Leg strength declined equally in both groups.

A 2 kg (4.4 lbs) loss of muscle is a large one, and likely significantly impairs health.

Resistance training is critical for weight loss and spares muscle

The groups in the above study performed no exercise during their weight loss. Could exercise help preserve muscle?

Yes, but only the right kind of exercise, strength training (resistance training, weightlifting).

Aerobic exercise does not preserve muscle during weight loss.

A study was designed to find any difference in terms of muscle mass between aerobic and resistance exercise during weight loss: Effects of Resistance vs. Aerobic Training Combined With an 800 Calorie Liquid Diet on Lean Body Mass and Resting Metabolic Rate. (2)

The subjects ate a very low calorie diet at 800 calories a day, and it consisted of 40% protein. One group did aerobics – walking, cycling, and stair climbing. The other did resistance training: “3 days/week at 10 stations which included four lower body and six upper body exercises for 12 weeks”.

The aerobics group actually lost quite a bit more body weight than the resistance training group, 18 kg vs 14 kg. Most people might think that this gives the advantage to aerobic exercise.

But there’s a catch.

The aerobics group lost 4 kg of muscle. The resistance training group lost none.

All of the weight lost by the aerobics group in excess of the resistance training group was muscle.

Will the aerobics group ever regain that muscle? Seems doubtful. This is probably a permanent loss for them. Even if they regain weight, it might be almost all fat tissue.

The conclusion has to be that if you lose weight without doing resistance training, you’re damaging your health.

Bodybuilders have a higher metabolic rate

Besides helping retain muscle during weight loss, resistance training and bodybuilding can help one stay lean and avoid fat gain to begin with, and that’s due to higher muscle mass.

Check out the following chart:


resistance training is critical for weight loss

Resting metabolic rate in bodybuilders vs controls.

The chart shows two things: 1) there’s a straight line correlation (r=0.89) between the amount of muscle mass and the resting metabolic rate; 2) even with the same muscle mass, bodybuilders burn more energy than controls.

So having more muscle mass from lifting weights greatly increases 24-hour energy expenditure.(3) This leads to fat loss, other things (like diet) being equal.

To lose fat, add muscle.


Weight loss without strength training leads to the loss of muscle as well as fat, an unhealthy situation, and higher protein intake doesn’t help.

Weight loss with strength training leads to no muscle loss.

And strength training leads to a higher resting metabolic rate and with it the ability to avoid fat gain.

There’s much more in this vein in my book, Muscle Up: How Strength Training Beats Obesity, Cancer, and Heart Disease, and Why Everyone Should Do It.


Leave a Comment:

Simon says December 15, 2015

Excellent article, I really enjoy reading what you write about weight training, and as of lately, iron.

I’m wondering about one thing though. You write here and in “Muscle Up” about test groups that have lost significant amount of muscle mass after having participated in various studies. But is that really impossible to gain back?

I’m just trying to understand the mechanics, and since you’ve written about all the things resistance training can accomplish, I find it hard to grasp that if one were to go on a diet high in protein and exercise (lift) regularly, it still wouldn’t be enough to gain back all that muscle. Could you please explain why it’s improbable to gain it back?

    P. D. Mangan says December 15, 2015

    Hi Simon, and thanks. Mainly what I’m getting at is that most of those people who lose muscle don’t and never will do any weight training. If they did, yes, they would regain the muscle. You can see also why yo-yo weight loss and regain are so bad: loss of muscle. I think most people just have no clue about the amount of muscle loss during a weight loss diet, or even that it happens.

      Simon says December 16, 2015

      Thank you for your answer!

      Then I understand what you mean. Couldn’t that also mean that someone who’s gone from overweight to normal through multiple diets would have less muscle than someone who is still largely overweight? How ironic if that’s the case…

      And you’re probably right when it comes to people not knowing about muscle loss. I don’t think I’ve ever, or at least very rarely, read or heard about losing muscle in conjunction with weight. The general perception seems to be that muscles are “disconnected” from the rest of the body, which is insane.

      Keep up the great writing.

      P.S I don’t know if you got it, but I sent a message about meditation as something to help with general cognitive and physical health a while back. Don’t know if you’re interested in looking that up, but as I enjoy your work, I would like to know your opinion about it. Thanks in advance.

BillyPilgrim says December 16, 2015

In a few days, I’ll be getting to my stage #1 goal of loosing ten percent of my body weight. Now at 200 lb., I’ll still be fatty, but a 10% loss is likely to be most beneficial if I now concentrate on muscle rehab and flexibility. My doc says to go for it but hasn’t really seen old farts build up.
I started this campaign after seeing a guy about my age (69) walk by and have his pants fall off – big gut, withered butt syndrome. I don’t know what to do about that. It’s too easy to injure your back and damage joints when lifting weights that build the major muscle groups. Supplements aside, do you have thoughts on how I can qualify for next year’s “Mr Buns” pageant?

Billy Pilgrim

    P. D. Mangan says December 16, 2015

    Yes, “big gut, withered butt syndrome” is all too common among older men. The exercise that does the most for that is squats. If you’re concerned about injury, try using a leg press machine and/or use lighter weights on the squats. I do both squats and leg press myself, as I believe most bodybuilders do. Leg press won’t have quite the same effect on the glutes as squats, but if you can’t do squats, then they can substitute.

Nothing to lose but your man boobs - Rogue Health and Fitness says February 8, 2016

[…] More importantly, aerobics will do nothing or maybe worse for losing weight, unless the weight you want to lose is muscle. For fat loss, the only proven exercise program is resistance training. […]

Belovar says August 3, 2016

Would you say that it is impossible to lose only fat without exercising?

    P. D. Mangan says August 3, 2016

    Yes, I would. Without exercise, 1/4 to 1/3 of lost weight is muscle. That goes even if your protein intake is high.

      Belovar says August 3, 2016

      Ok. Maybe you have already written about this, but what will be the effect of a ketogenic diet, with 100% caloric intake, and no exercise?

        P. D. Mangan says August 3, 2016

        I’m open to consulting with you on that. Low rates!

          Belovar says August 4, 2016

          I must admit I don’t know how to interpret your answer. 😀

          If I understand it correctly, the body makes ketones from fat, and that this is the case even if one exercises or not.


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