I slept 5.5 hours a night during my diet just to fit in more training: two weeks later, I understood what my body had been burning instead of fat
A landmark study shows that cutting sleep to fit in more training during a diet is counterproductive: participants on the same calorie deficit lost 55% less fat when sleeping 5.5 hours versus 8.5 hours. Instead of fat, their bodies burned muscle, organ tissue, and lean mass—a shift driven by hormonal changes that happen almost immediately.