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Published on: 7/9/2025

What happens to the body when calorie intake is very low?

When you eat very few calories, your body starts to use stored fat and muscle for energy, which can change your metabolism and body composition.

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Explanation

When the body gets very few calories, it has to find energy somewhere else. It starts by using fat stored in the body. This is why people can lose weight on very low-calorie diets. However, the body might also use muscle for energy, which is not always good because muscles are important for strength and health.

Metabolic Changes

  1. Energy Use: The body switches to using fat and muscle for energy because it isn't getting enough from food.
  2. Metabolism: Your metabolism, which is how fast your body uses energy, can slow down. This is because your body tries to save energy when it thinks it is not getting enough food.

Body Composition

  • Fat Loss: You may lose fat, which can be a goal for some people.
  • Muscle Loss: Losing muscle can make you weaker and is usually not good for your health.

Overall, eating too few calories can lead to weight loss, but it might also lead to losing muscle and slowing down your metabolism. This can affect how your body works and how you feel.

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