Impact on Energy Balance and Body Composition

Intermittent fasting can have significant impacts on energy balance and body composition. By reducing energy intake, intermittent fasting can create a negative energy balance, where the body burns more calories than it consumes. This can lead to weight loss and improvements in body composition. Additionally, intermittent fasting can improve energy expenditure, increasing the number of calories burned by the body. This increase may be due to an increase in metabolic rate or an increase in the body’s use of stored fat as an energy source.

During intermittent fasting, the body initially uses up its stored glucose (glycogen) for energy. Once the glycogen stores are depleted, the body turns to stored fats as an energy source, a process known as lipolysis. Fatty acids are released from adipose tissue and transported to the liver, where they are converted to ketone bodies. These ketone bodies can be used by the body as an alternative energy source during the fasting period.

The body can also break down protein (muscle) for energy during fasting, but this is generally not preferred as it can lead to muscle loss. The body tries to preserve muscle mass by prioritizing fat as an energy source instead.

Body Composition

Body composition refers to the relative amounts of fat, muscle, bone, and water in the body. Intermittent fasting can impact body composition by influencing both fat loss and muscle preservation.

During weight loss, it’s common to lose both fat and muscle mass. However, preserving muscle mass is important for maintaining metabolic rate and overall health. Intermittent fasting may help to preserve muscle mass during weight loss by promoting the production of human growth hormone (HGH), which supports muscle growth and maintenance.