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Weight loss typically involves the loss of fat, water and muscle. Overweight people, or people suffering from obesity, typically aim to reduce the percentage of body fat. Additionally, as muscle tissue is denser than fat, fat loss results in increased loss of body volume compared with muscle loss. Reducing even 10% body fat can therefore have a dramatic effect on a person's body shape. To determine the proportion of weight loss that is due to decreased fat tissue, various methods of measuring body fat percentage have been developed. Muscle loss during weight loss can be restricted by regularly lifting weights (or doing push-ups and other strength-oriented calisthenics) and by maintaining sufficient protein intake. Those on low-carbohydrate diets, and those doing particularly strenuous exercise, may wish to increase their protein intake. According to the National Academy of Sciences, the Dietary Reference Intake for protein is 0.8 grams per kilogram of body weight for adults. Endurance athletes, such as those who compete in distance running or cycling require many more calories in order to maintain weight. Due to the large caloric intake these athletes must consume it can be particularly tricky to ensure they obtain the nutrition required to maintain muscle mass.[18] Excessive protein intake, though not connected to declined kidney functioning in healthy individuals,[19][20] may be harmful to those with certain kidney diseases.[21] There is no conclusive evidence that moderately high protein diets in healthy individuals are dangerous; it has only been shown that these diets are dangerous in individuals already suffering from kidney and liver problems. The Basal Metabolic Rate, which is the amount of calories the body expends at rest, meaning without performing any physical activity, is influenced by the person's total weight and total amount of muscle. The more muscle, the more calories a person can burn naturally. When the amount of muscle is increased, then more calories can be ingested without gaining weight. Conversely, if the amount of fat is increased, increasing the number of calories ingested will only add weight. Normally, when people lose weight, they lose a combination of fat and muscle. If the diet plan includes a daily caloric intake greater than the basal metabolic rate (BMR), the person will most likely lose fat. In contrast, if the person follows a diet that includes a lower caloric intake than the BMR, this person will lose fat but also a higher percentage of muscle.[citation needed] Severe diets may make people lose 50% fat and 50% muscle weight thus affecting their metabolism because by losing muscle the BMR is affected. Maintaining muscle mass while losing fat is therefore a key factor to reach both the ideal weight and body composition. |
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