Late-night eating raises the risk of obesity and diabetes.

In recent decades, busy lifestyles have drastically altered sleeping patterns, with late-night eating and staying up late becoming increasingly common. This shift has led to shortened sleep durations and is particularly prevalent in industrialized nations. These changes in behavior have paralleled the rise in obesity and diabetes. Emerging evidence suggests that eating late at night and experiencing chronic sleep deprivation may heighten the risk of these conditions.

A new study published in the Endocrine Society’s Journal of Clinical Endocrinology & Metabolism reveals that late-night meals and snacks can increase the risk of obesity and diabetes. This comprehensive study involved participants wearing activity trackers, undergoing hourly blood sugar sampling, sleep studies, body fat scans, and consuming food with non-radioactive labels to measure fat oxidation rates.

Another study highlights how eating a late dinner can impair glucose tolerance and reduce fat burning. The impact of late eating varies between individuals and is influenced by their usual bedtime, according to Jonathan C. Jun, M.D., from Johns Hopkins University School of Medicine. “This indicates that some people may be more susceptible to the effects of late eating. If the metabolic disturbances observed from a single late meal persist chronically, they could potentially lead to conditions like diabetes or obesity.”

In the study, 20 healthy volunteers (10 men and 10 women) were observed to compare the effects of a dinner eaten at 10 p.m. versus 6 p.m. All participants went to bed at 11 p.m. Results showed that blood sugar levels were higher and fat oxidation was lower after the late dinner, even though the same meal was consumed at both times. "On average, peak glucose levels after a late dinner were about 18 percent higher, and fat burning overnight decreased by about 10 percent compared to an earlier dinner. These effects might be more pronounced in individuals with obesity or diabetes, who already have compromised metabolism,” explained Chenjuan Gu, M.D., Ph.D., the study’s first author.