Older Lean Adults Burn Fat Better Overnight

Body composition significantly influences how efficiently the body burns fat during sleep, according to recent European research. A study analyzing 18 past investigations involving 187 participants found that older, leaner individuals metabolized fat overnight just as effectively as younger lean individuals. This suggests that age alone is not the determinant of slower fat burning.

The research highlighted that individuals with higher body fat percentages, particularly older overweight or obese participants, burned less fat and more carbohydrates during sleep. This shift in fuel usage was strongly linked to elevated fasting triglyceride levels, a measure of fat circulating in the blood after an overnight fast.

These findings indicate that maintaining a higher muscle-to-fat ratio can enhance the body's ability to burn fat overnight. Fasting triglycerides, routinely checked in cholesterol panels, serve as a critical indicator of energy metabolism and nighttime fat utilization. The study, published in Diabetologia in May 2026, offers new insights into metabolic health and controllable factors influencing calorie expenditure.