How To Lose Fat And Gain Muscle Simultaneously

One of the major problems with going on a very calorie-restricted diet is that, along with fat, you are also likely to lose some lean muscle mass. You may have heard that you need to lose weight before you can start building muscle in order to avoid this, but is there any evidence to back this advice?

Read on to discover why it’s important to differentiate between fat weight loss and muscle weight loss, and what you can do to try to preserve muscle mass while maximizing fat loss.

Fat loss vs. muscle loss

When you follow an energy-restricted diet, your body is forced to dip into its existing energy stores to meet your ongoing daily energy demands. The energy store that your body usually utilizes is existing fat and muscle.

Studies have shown that energy-restricted diets lead to weight loss that is approximately 20-30% lean muscle mass loss, with the remainder being fat loss.¹

This effect seems to become even more significant as you get older.²

Since your lean muscle mass decreases by 3-8% per decade from the age of 30,³ you don’t want to exacerbate this trend by excessive restrictive dieting.

Lean muscle mass has a higher resting metabolic rate (it requires more energy, or uses more calories, at rest) than fat, so the higher your lean muscle mass, the higher your resting metabolic rate, this is due to the amount of energy the body uses to maintain the lean muscle mass.⁴ Someone with high lean muscle mass and low body fat will burn more calories at rest than someone who is the same weight but has high body fat and low lean muscle mass.

How to preserve muscle mass while losing fat weight

Fortunately, there are ways to lose fat weight while maintaining muscle mass. You can adhere to a diet and lose fat without losing muscle. In fact, it’s possible to lose fat and actually build muscle at the same time.

Exercise

Moderate exercise has been shown to reduce loss of muscle in older, overweight, or obese people who are following an energy-restricted diet. One study compared two groups of participants both following a calorie-restricted diet. One of the groups did moderate-intensity walking for 35-45 minutes, three to five times a week. The other group did no exercise. Both groups lost a similar amount of weight; however, the exercise group lost fat weight and retained muscle mass, while the non-exercise group lost both fat and muscle mass.⁵

These findings were validated by another study that showed that aerobic exercise, defined as 300 minutes of intense exercise per week, lessened muscle loss in people following a calorie-restricted diet.⁶

Resistance training has been shown to increase lean muscle mass while simultaneously decreasing fat mass. A study evaluating the effects of ten weeks of resistance training found it to increase lean muscle mass by 1.4kg, decrease fat mass by 1.8kg, and increase resting metabolic rate by 7%.⁷

Diet

The food you eat can also influence whether you maintain muscle mass while trying to lose weight. Following a high-protein diet has been shown to help preserve lean muscle mass while following a calorie-restricted diet. Ideally, a high-protein diet should contain both lean animal protein and plant-based protein. The effects were even more pronounced when a high protein diet was combined with aerobic and resistance training.⁸

A large meta-analysis of 20 randomized trials on older people following a weight loss diet with calorie restriction found that those who had a higher protein intake (more than 1g/kg/day) were able to retain more lean muscle mass and lose more fat weight than those with a lower protein intake.⁹

It’s important to note that the recommended dietary intake of protein is 0.8g/kg per day for people who are not exercising. That intake should increase to 1.0g/kg/day, 1.3g/kg/day and 1.6g/kg/day if the person is doing mild, moderate, or intense physical activity respectively. Higher and long-term protein consumption above 2g per kg per day could be dangerous and may result in renal and digestive disease. Further, those with any renal or inflammatory bowel issues must take great caution when it comes to the level of protein consumption.¹⁰ It’s always best to consult your physician before starting a high protein diet.

Supplements

Essential amino acid supplementation may aid in increasing lean muscle mass, especially in older people. A study evaluating the impact of oral essential amino acid supplementation (8g twice daily) showed that this can significantly increase lean muscle mass in older people with sarcopenia (accelerated age-related muscle loss).¹¹

How to tell if you are losing fat or muscle

Just standing on a regular scale is not going to help you differentiate between whether your weight loss is due to fat or muscle loss. A regular scale measures the amount of weight you’ve lost, but it can’t determine whether you’ve lost two pounds of fat or two pounds of muscle.

Muscle is denser than fat, so two pounds of fat will look a lot different from two pounds of muscle. This is important if you are dieting and exercising at the same time. The weight on your scale may not change, but your appearance can change quite dramatically as you lose fat and replace it with denser - but trimmer - muscle.

There are a few different options for differentiating between muscle weight and fat weight, ranging from simple to very complex.

1. Skin calipers

Skin calipers are a simple tool that measures the amount of fat that you have just under your skin (skinfold or subcutaneous fat). Measurements are taken at different places on your body and then entered into a formula that gives you your percentage of body fat and lean muscle mass.

Regular skinfold measurements are a great way to monitor fat loss and lean muscle gain, provided the measurements are taken by someone who is experienced and trained in using skin calipers.

2. Impedance scales

Impedance scales, or body fat scales, use bioelectrical impedance to measure your body fat.

You stand on the scale barefoot, and a weak electrical current is transmitted through your body. The scale measures the resistance to the current, which varies depending on your body composition.

Bioimpedance scales are a simple way to measure body fat, but they can be inaccurate depending on hydration changes and various other factors.¹²

3. DEXA (dual-energy x-ray absorptiometry) scanning

DEXA scanning is considered the gold standard in measuring body composition. DEXA scanning can precisely measure changes to the percentage of body fat and lean muscle mass.

Is there a difference between men and women when it comes to losing fat vs. losing muscle?

Men generally have a higher percentage of lean muscle mass than women which, in turn, means that they have a higher resting metabolic rate (men burn more calories than women just to maintain their bodies). If calorie consumption is equal in men and women during the course of a diet, men will usually lose weight more quickly.

Even after dieting, the percentage of muscle mass relative to the percentage of fat is higher in men than women.

An interesting study looked at weight loss in men and women with diabetes following a low-energy diet. After eight weeks, men had lost 16% more weight than women and they had lost more fat than women, while women had a larger reduction in hip circumference, fat-free mass, and HDL cholesterol¹³ Further research needs to be done to determine the differences in lean muscle mass loss between men and women.

The lowdown

Calorie-restricted diets lead to both muscle mass and fat loss. While fat loss is beneficial, muscle mass loss is not. You want to try to preserve muscle mass both because it increases resting metabolic rate and because maintaining muscle mass with aging improves morbidity and mortality.

Fortunately, there are measures that you can take to help you lose fat while preserving or building muscle. Adding exercise and aerobic and/or resistance training to your weight loss plan helps to preserve muscle mass, as does focusing on eating a high protein diet.

The best way to measure fat loss and muscle gain is DEXA scanning; however, if you don't have access to this, skinfold calipers or bioelectrical impedance scales can be used.