Weight loss: what percentage of the body is fat, and what percentage is muscle?

When starting a weight loss program, most people focus on the amount of weight lost, forgetting that not all the weight lost is fat. In fact, weight loss involves losing fat, muscle, and water.

Losing too much muscle can slow down your metabolism, making it easier to regain weight and weakening your physical strength. Conversely, maintaining muscle mass while burning fat will result in a toned, healthy body and make it easier to maintain your weight, according to the health website Verywellfit (USA).

Losing weight too quickly by drastically cutting calories will lead to significant muscle loss.

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The rate of muscle and fat loss during weight loss will depend on the following methods:

Dieting, no exercise.

Many people choose to cut calories without exercising, leading to rapid weight loss but also a significant loss of muscle mass.

A study published in The American Journal of Clinical Nutrition showed that when losing weight solely through dieting, approximately 20-25% of the weight lost is lean muscle. This occurs because insufficient calorie intake causes the body to not only mobilize fat but also break down muscle protein for energy.

Therefore, losing weight solely through dieting may lead to rapid weight loss, but it can easily cause muscle loss and slow down metabolism. Furthermore, weight returns more quickly after stopping the diet.

When combining dieting with weightlifting

Strength training is the most important factor in preventing muscle loss during weight loss. When combining a moderately reduced-calorie diet with exercises such as weightlifting, squats, or push-ups, the body will prioritize burning fat over muscle.

According to the same study, combining dieting with strength training or adequate protein intake can reduce muscle loss by 10-15%. In some cases, a moderately calorie-restricted diet with high protein intake and strength training can not only maintain but even slightly increase muscle mass.

This happens because the mechanical stimulation during exercise helps activate muscle protein synthesis, thereby balancing the breakdown of muscle protein caused by calorie reduction. As a result, exercisers burn fat while maintaining muscle mass and strength.

Extreme calorie restriction

Cutting calories drastically will create a large energy deficit. This can lead to rapid weight loss. However, the consequence is that you will lose more muscle than fat.

Rapid weight loss reduces glycogen and water in the muscles, causing a significant weight drop in the first few days, but this is mainly water and muscle, not fat. Some research evidence suggests that about 30-50% of the weight lost this way is lean muscle.

Because when calories are drastically reduced, the body experiences a severe energy deficit, and thyroid hormone and insulin levels decrease. As a result, the body enters an energy conservation mode. At this point, muscle protein is broken down to produce glucose for the brain, leading to significant muscle loss, according to Verywellfit.

Source: https://thanhnien.vn/giam-can-co-the-mat-bao-nhieu-la-mo-bao-nhieu-la-co-185251109135157892.htm