In adults with prediabetes and short sleep duration, lifestyle intervention and lifestyle intervention plus sleep extension result in similar, non-significant reductions in waist circumference over an 8-week period, indicating that sleep extension does not enhance fat loss beyond diet and exercise alone.

When a person eats less and moves more, the body burns stored fat for energy until it reaches a new balance where energy intake matches energy use. Adding more sleep does not change this balance because the body adjusts its metabolism and hunger signals to match the reduced calorie intake and increased activity, so fat loss stops at the same point whether sleep is extended or not.