Essentially, the body consumes more calories than the body consumes. The total metabolic level of our body is determined by basal metabolism, active metabolism and the thermal effect of food, and basal metabolism accounts for about 65%-70% of the body's total metabolism. Basal metabolic value refers to the minimum amount of energy that the body spends to survive at rest each day.
When your daily caloric intake is lower than your body's basal metabolic value, your body will fall into a state of famine, and your body will turn on the protective mechanism, turn off certain non-emergency functions, automatically reduce your basal metabolism, and rely on low energy to survive. When the basal metabolism is lowered, the calories needed are reduced, and what is eaten is preferentially converted into fat. Since the decrease in "lean body mass" (a general term for non-fat components of the body) is more obvious, the body fat percentage will increase instead, which is what we commonly call lean and fat.
During the first few days of caloric deprivation, the body uses up stored glycogen. Glycogen, as a form of energy storage, comes from the carbohydrates you eat. Since carbohydrates are the body's main energy**, that's why any glucose that the body doesn't use right away is stored (in the liver, muscles, and fat cells) for later use.
But because carbohydrate molecules bind to water, this means that when the body stores glycogen, it also stores water in the muscles. When these stored glycogen are depleted, the body also releases large amounts of water. This is often referred to as "water weight", which explains why some people feel like they've lost a lot of weight early in the day of a diet.
Considering that you can only store glycogen for a few days, the body uses fat to store extra calories in case you need them. Once the stored glycogen is used up, the body begins to metabolize fat to get the energy it needs for physiological activity. But not all tissues, such as the brain, can use fat for energy. That's why when you're low on calories, your body needs to metabolize your muscles.
Protein (from the food you eat) is stored in your muscles. The body can convert stored protein into glucose for energy. When you go on a diet, you lose not only fat but also muscle. This can have a lot of adverse effects not only on your health and strength, but also on your metabolism. This can lead to serious consequences – including slowing down metabolism and ultimately leading to weight in the back.
Poor diet and malnutrition can also affect muscle loss – in general, appetite and food intake decline with age.
A few misconceptions about muscle loss.
It was once thought that the more fat you have, the less muscle you lose when you're low on calories, but this belief has since been overturned. This is because both lean and fat people have a high rate of muscle loss while dieting. However, race and genetics may play a role – studies have shown that blacks tend to lose more muscle mass than whites in calorie deficits. Some studies have also shown that genetic variants may make some people more susceptible to certain dietary changes, which may determine how much muscle mass they end up losing.
Whether you do it gradually** or quickly**, the muscles will decrease. One determining factor of how much muscle you'll lose is how much weight you end up losing. Studies have shown that if a person loses 10% of their body weight, one in five is fat-free (such as muscle). That's the equivalent of a few kilograms of muscle.
Many of the best ways to control calorie intake are to encourage the body to prioritize fat burning. It's a common belief that if you eat a lot of protein, you're less likely to lose muscle mass. This is controversial because studies have shown that people who follow a high-protein diet** lose as much muscle as those who follow other diets.
Low-carb diets are also thought to promote fat loss. But the study found that the low-carb + high-fat diet and the low-fat + high-carb diet seemed to work equally well or better at fat loss — but no difference in muscle loss.
Protein and exercise.
In summary, the only way to prevent muscle loss in the process is to combine exercise, especially resistance and endurance exercises, with a high-protein diet. This is because exercise stimulates muscle growth, but this process can only happen if you have enough protein**.
It is recommended that adults consume 0. per kilogram of body weight per day8 grams of protein to preserve muscle mass. But considering the additional muscle demands of exercise, a person may need to consume 1. per kilogram of body weight2-1.5 grams of protein to maintain muscle in the process. People who exercise regularly may need to increase it to more than 2 grams per kilogram of body weight when they are **. Older adults may also need to consume more protein than average.
But avoid consuming too much protein (more than 2. per kilogram of body weight5 grams), because consuming more protein than your body needs may adversely affect your metabolism as it may make it impossible for the body to absorb glucose for energy. It may also put more stress on the kidneys and liver, which can lead to serious health problems such as liver and kidney damage.
Even if you prevent muscle loss, other metabolic changes can still occur, promoting weight regain – such as changes in your basal metabolic rate and increased appetite and hunger. That's why, when it comes to **, the most important thing is to consider the sustainability of your diet and lifestyle changes. The easier it is to keep these things, the better your chances**.