Not enough sleep? No chance of weight loss. Blood sugar issue likely.

Circadian rhythm has been shown to be related to glucose metabolism and risk of diabetes, probably through effects on energy balance. Recent genome-wide association studies identified variants in circadian rhythm–related genes associated with glucose homeostasis.

In a February American Journal of Clinical Nutrition study, the variants CRY2 rs11605924 and MTNR1B rs10830963 were genotyped in overweight or obese adults who were randomly assigned to 1 of 4 weight-loss diets that differed in their proportions of macronutrients.

The data results indicate that variants in the circadian-related gene CRY2and MTNR1B may affect long-terms changes in energy expenditure by slowing it down, and dietary fat, carbohydrate intake may modify the genetic effects adversely.