In a study, a sleep-deprived group (5.5 hours of sleep) lost 75% of their weight from lean mass, with fat loss cut in half, compared to an 8-hour sleep group where half the weight lost was fat.

A single night of poor sleep negatively affects muscle recovery.

Lack of sleep can double the time it takes to get abs.

Multiple long-term studies have found that consistently poor sleep dramatically slows muscle growth and fat loss.