A big concern for anyone who cares about the future is maintaining muscle. Any time you lose weight, a portion of that weight is body fat and the rest is lean tissue, mostly muscle. The proportions depend on a variety of factors which we will get into below, but for the average overweight dieter, 70 percent of the weight lost is from fat and 30 percent is from muscle.
Losing muscle is a problem: It lowers your metabolic rate and reduces insulin sensitivity, a combination that sets you up to experience rebound weight gain.
Muscle also protects against disease by serving as a reservoir for proteins used by the immune system. In older individuals, muscle loss coincides with increased risk of disease and mortality. Meanwhile, for athletes, muscle loss hampers performance and may increase injury risk.
It’s safe to say that preserving muscle mass is a primary goal during fat loss. This article will discuss the nuances of human metabolism and give you proven strategies that can reduce muscle loss when losing body fat.
How Much Muscle Do You Stand To Lose During Weight Loss?
The standard rule is that people who go on a low-calorie diet and don’t exercise will lose about 70 percent body fat and 30 percent lean muscle mass over the course of a diet. However, baseline body composition plays a large role in how much muscle you are likely to lose. Where overweight individuals are more likely to experience the 70/30 fat/muscle split, leaner individuals are not so lucky. Studies show that in men with body fat below 10 percent, as much as 50 or 60 percent of the weight lost during a diet will be from muscle and only 40 to 50 percent will be from body fat.
Scientists theorize that the human brain is able to sense how much fat is stored on the body. This allows for the brain to regulate which tissues are being burned for energy: Fat or muscle?
When overweight people diet, the brain doesn’t feel as threatened and a greater proportion of the weight loss is from fat, whereas with leaner individuals, the brain senses the lack of body fat as a threat, holding on to fat tissue while increasing the oxidation of muscle.
A second factor that impacts body composition changes during weight loss is the severity of the diet. A big mistake many people make is to slash calories below 1,200 a day. They want to lose fat quickly, so they figure more of a deficit is better. This backfires because the greater the energy deficit, the larger relative muscle mass losses. If that’s not enough, low-calorie dieting brings with it a metabolic slow down whereby the body reduces resting metabolic rate so that you burn fewer calories daily.
Strategies That Preserve Muscle During Weight Loss
Fortunately, there are three proven strategies to preserve muscle during weight loss:
Train with weights
Use gradual rates of weight loss
#1: Increase Protein
Getting a greater proportion of your calories from protein helps preserve muscle during weight loss. It works like this: Based on the availability of amino acids from protein, the body is constantly in a fluctuating state of muscle loss and gain. Anytime you replenish the pool of amino acid building blocks by eating protein, it’s a good thing, stimulating protein synthesis and protecting the muscle you’ve got.
Studies indicate that a minimum of 1.6 g/kg of protein will blunt muscle loss when dieting. For someone weighing 165 lbs, this equals 75 kg in body weight, so you need a minimum of 120 grams of protein daily.
There may be a benefit of going as high as 2.4 g/kg of body weight, especially if the program is combined with strength training. For example, a recent Canadian study compared the effect of 1.2 g/kg or 2.4 g/kg of protein a day during weight loss and found that the group eating 1.2 g/kg of protein maintained muscle, while losing 3.5 kg of body fat. The higher protein group that ate 2.4 g/kg actually gained 1.2 kg of muscle while losing 4.8 kg of fat.
#2: Train With Weights
Research shows that all types of exercise can help prevent muscle loss when losing weight. Strength training and other anaerobic modes like sprinting appear to be most effective because they overload the muscle, triggering a protein synthesis pathway known as mTOR that preserves muscle. Another benefit of anaerobic exercise is that it maintains strength, which leads people to be more spontaneously active.
This is a game changer because when people lose weight they often become more sedentary, reducing activity and lowering the number of calories burned over the course of the day. For example, in one weight loss study, women who strength trained increased their spontaneous energy expenditure, burning an extra 63 calories daily, whereas a group that had no exercise intervention became more sedentary, decreasing energy expenditure by a whopping 259 calories.
#3: Use A Gradual Rate of Weight Loss
Moderate rates of weight loss do not present as much of a shock to the body and allow for greater preservation of lean mass. This is especially true in athletes and leaner individuals (including people in the overweight category who are not obese). A 2012 study of athletes illustrates this: Researchers compared what would happen with a 500-calorie a day diet or a 1,000-calorie diet. Results showed that although it took the athletes three weeks longer to lose 5 percent of bodyweight with the 500-calorie deficit diet, the greater daily energy intake allowed them to gain 2.1 percent muscle mass at the same time.
The group on the 1,000-calorie deficit diet lost 5 percent of bodyweight in 5 weeks and dropped 0.2 kg of muscle. Both groups ate a higher protein diet and did a heavy weight-training program in conjunction with regular sport training, which is likely the reason the muscle loss in the 1000-calorie deficit group was not greater.
Take Away: Set yourself up for long-term success by taking action to preserve muscle mass when losing weight: Combining strength training with a higher protein diet with a gradual rate of weight loss will allow you to optimize body composition with the least struggle.
Garthe, Ina. Changes in Body Composition and Performance in Elite Athletes During A Period with Negative Energy Balance Combined with Strength Training. Eighth International Conference on Strength Training. Norwegian School of Sports Sciences. October 2012
Heymsfield, S., et al. Weight Loss Composition is One-Fourth Fat-Free Mass: A Critical Review and Critique of This Widely Cited Rule. Obesity Reviews. 2014. 15(4): 310–321.
Pasiakos, S., et al. Effects of high-protein diets on fat-free mass and muscle protein synthesis following weight loss: a randomized controlled trial. The Journal of the Federation of American Societies for Experimental Biology. 2013. 9, 3837-3844.