There is a general consensus in science that creating a caloric deficit leads to weight loss. However, not all weight loss is treated equally, metabolically speaking. Maintaining muscle mass is important for overall health, so how do we avoid losing muscle while restricting calories to lose fat? Heather Huntsman, Ph.D., CSCS dives into the science of body composition and nutrition with helpful “signals” that cue the body to offset muscle loss and increase lean body mass.
Despite all the noise you hear in the fad diet world, the fundamental variable that determines weight loss is a relative energy deficit created by restricting the calories you consume, increasing the number of calories you burn by moving more, or a combination of the these two methods.1 For those of you that are a little more “plugged in” to the importance of body composition, you know that not all weight loss is beneficial weight loss. By following the traditional recommendations of “eat less, move more,” (which is likely in the form of cardio) the typical ratio of weight loss falls somewhere in the range of 75% fat loss and 25% muscle loss.1,2 What’s the problem here? A loss of muscle ultimately negatively impacts metabolism, as muscle mass is a major contributor to metabolic rate. This translates to an experience many of us have encountered: the more weight we lose, the harder it becomes to lose weight.
Knowing this, the next logical question might be: “is there a way to lose weight and not lose muscle?” Or better yet: “is there a way to lose weight and actually improve body composition by gaining muscle at the same time?”
To properly answer these questions, it is important to understand concepts of muscle maintenance and hypertrophy (i.e. muscle growth, or “gains”). Skeletal muscle, like all tissues in the body, is in a constant state of breakdown and repair. There are certain signals that influence its breakdown, and other signals that influence the building up of the tissue, or “synthesis.” What’s important is the balance of these signals, meaning when breakdown and synthesis are equal, muscle mass is maintained. In contrast, when breakdown is greater, there is a loss of muscle – and greater synthesis leads to muscle growth.1
So, what does the science say? Which signals drive muscle breakdown, which signals drive synthesis, and can you use those signals in your favor to lose weight while maintaining – or even increasing – muscle mass?
|Key Signal||Primary Outcome|
|Energy Restriction (Dieting)||Increased muscle breakdown3|
|Consuming Protein||Increased muscle growth1|
|Resistance Training (lifting weights)||Increased muscle growth1-5|
|High Intensity Training||Increase in hormones like growth hormone that increase muscle growth4|
The answer is “yes,” with a few caveats. Although a caloric deficit will increase muscle breakdown, as demonstrated in the table above, there are several strategies to implement during calorie restriction to offset this affect and increase synthesis rates to a level that may allow for muscle maintenance or even growth. The way to accomplish this is to:
- Increase the amount of protein consumed (which can come from plant or animal sources) to 2-3 times the recommended daily amount (i.e. 1.2-2.4g/kg of body weight per day) while accounting for the calorie deficit. There are many studies that show this is an independent signal for increase muscle growth.1-4
- Incorporate resistance training into your weekly workout routine. Depending on how you break up your workouts, you could do this 2-5 times per week. Resistance training is a proven method for increasing muscle hypertrophy for up to 48 hours after the exercise bout.1-5
- HIT training has been shown to increase the release of growth hormone which independently signals to muscles to grow. You can incorporate this into your training routine 2-3 times per week to maximize your muscle growth potential.4
- Combining these three signals can synergistically increase your muscle building potential.5
Finally, to make this an even more precise science, the best way to ensure weight loss is primarily fat loss and not muscle loss is to regularly test your body composition to specifically measure whether your strategy is effectively achieving your goal. How much weight you want to lose, as well as how much fat you have to lose will affect the rate at which you can achieve these goals. Slower rates and less aggressive caloric deficits are often needed to shift body composition in favor of greater muscle mass and lower body fat percentages.5
- Churchward-Venne TA, et al. (2013) Role of protein and amino acids in promoting lean mass accretion with resistance exercise and attenuating lean mass loss during energy deficit in humans. Amino Acids 45:231-240. doi: 1007/s00726-013-1506-0.
- Hector AJ and Phillips SM. (2018) Protein Recommendations for Weight Loss in Elite Athletes: A Focus on Body Composition and Performance. International Journal of Sport Nutrition and Exercise Metabolism 28:170-177. doi: 10.1123/ijsnem.2017-0273
- Hector AJ, et al. (2017) Pronounced energy restriction with elevated protein intake results in no change in proteolysis and reductions in skeletal muscle protein synthesis that are mitigated by resistance exercise. Federation of American Societies for Experimental Biology (FASEB) 32:265-275. doi: 10.1096/fj.201700158RR.
- Longland TM, et al. (2016) Higher compared with lower dietary protein during and energy deficit combined with intense exercise promotes greater lean mass gain and fat mass loss: a randomized trial. American Journal of Clinical Nutrition 103:738-746. doi: 10.3945/ajcn.115.119339.
- Aragon AA et al. (2017) International society of sports nutrition position stand: diets and body composition. Journal of the International Society of Sports Nutrition 14(16):1-19. doi: 1186/s12970-017-0174-y.