A Muscle-Centric Perspective on Intermittent Fasting: A Suboptimal Dietary Strategy for Supporting Muscle Protein Remodeling and Muscle Mass?

Without enough dietary protein, the body cannot build new muscle and will lose muscle mass over time.

When energy intake is low during intermittent fasting, more protein is needed in each meal to fully activate muscle protein synthesis, making it more difficult to preserve muscle mass while losing weight.

Consuming the same total amount of protein in four smaller meals instead of two large ones leads to higher muscle protein synthesis over a full day because muscle tissue stops responding to protein for several hours after each dose.

Fasting for 16 hours or more increases the rate at which muscle proteins are broken down and reduces net muscle protein retention over 24 hours compared to eating more frequently.

Consuming more than 0.25 grams of high-quality protein per kilogram of body weight in a single meal does not increase muscle protein synthesis beyond that point; excess protein is instead broken down for energy.

Prolonged intermittent fasting reduces amino acid availability, lowers muscle protein synthesis, increases muscle protein breakdown, and leads to a net loss of muscle protein over 24 hours, which can reduce muscle mass over time in older adults or people consuming insufficient calories.