Sleep, Weight and Metabolism

What the research links

Large studies consistently associate short sleep with a higher risk of obesity and type 2 diabetes. The CDC and NHLBI list both among the health risks of not getting enough sleep. Controlled lab studies help explain why: sleep loss changes appetite hormones, increases hunger and cravings for energy-dense food, and reduces insulin sensitivity.

Sleep and dieting

In a 2010 study published in Annals of Internal Medicine, adults on a calorie-restricted diet spent two weeks sleeping 8.5 hours and two weeks sleeping 5.5 hours. They lost similar amounts of weight, but when sleep was restricted, a much smaller share of the weight lost was fat and more was lean tissue, and they reported more hunger.

Getting more sleep may reduce calories

A 2022 randomized trial in JAMA Internal Medicine enrolled adults with overweight who habitually slept less than 6.5 hours. After a single sleep hygiene counselling session aimed at extending sleep, the sleep extension group slept about 1.2 hours more per night and ate roughly 270 fewer calories a day than the control group, without other diet changes, in their normal lives.

Timing and blood sugar

Eating late at night, when your body clock expects fasting, may be handled less efficiently than the same food earlier in the day, according to circadian research. Irregular schedules and night shift work are associated with higher metabolic risk.

Sleep apnea and weight

Excess weight is a major risk factor for obstructive sleep apnea, and untreated sleep apnea causes fragmented sleep and daytime fatigue that make healthy choices harder. Weight loss can reduce sleep apnea severity, and treating sleep apnea can improve energy. If you snore loudly or are tired despite enough sleep, ask about testing.

Practical steps

• Aim for at least 7 hours of sleep a night as an adult.
• Keep regular sleep and meal times.
• Eat most of your food earlier in the day where practical, and avoid large late-night meals.
• Notice whether tiredness drives snacking, and plan for it.
• Get evaluated for sleep apnea if you have symptoms.