Eating close to bedtime ups risk of obesity

Meal timing appears to have an impact on body mass index (BMI), with higher dietary consumption after waking up and lower consumption close to bedtime correlating with lower BMI, according to a recent study. However, such relationship varies by chronotype. In addition, an association exists between timing of carbohydrate and protein intake and obesity.

A higher consumption of total daily energy during the morning period correlated with lower chances of being overweight or obese (odds ratio [OR], 0.53; 95 percent CI, 0.31–0.89), and this relationship appeared to be stronger among individuals with an earlier chronotype (OR, 0.32; 0.16–0.66).

On the other hand, higher total daily energy intake during the night window correlated with higher chances of being overweight or obese (OR, 1.82; 1.07–3.08), especially among those with a later chronotype (OR, 4.94; 1.61–15.14).

These associations were more robust for carbohydrates and protein intakes than for fat intake.

“Our findings highlight the importance of considering timing of intake relative to sleep timing when studying the associations of meal timing with obesity and metabolic health,” the investigators said.

This study measured BMI, chronotype and dietary intakes in 872 middle-to-older-aged adults by six 24-hour dietary recalls in 1 year. Four time windows of intake relative to sleep timing were identified: morning (within 2 hours after getting out of bed), night (within 2 hours before bedtime) and two midday periods in between (split by the midpoint of the waking period).

“Timing of dietary intake may play a role in obesity. However, previous studies produced mixed findings possibly due to inconsistent approaches to characterize meal timing and not taking into account chronotype and macronutrients,” the investigators noted.