Adults who are attempting to lose weight should stop eating when it’s dark and consume their largest meal(s) earlier in the day if possible, according to a new study.
Earlier this week, we reported that skipping breakfast could benefit type 2 diabetes and may help with weight loss, if followed long-term.
In this new study, researchers from Brigham and Women’s Hospital in Boston explored the evidence for and against eating in the late afternoon or evening.
They have studied the association between daily eating patterns, leanness and the circadian rhythm (light-dark cycle), which influences body weight.
The study tracked the eating habits and sleep times of 110 college students for 30 days to establish whether fasting in accordance with circadian timing had an effect on metabolism.
Pictures of food intake and time of food intake were logged by students through a mobile app, and the sleep-wake timing was monitored with diaries of sleeping habits as well as a wrist motion device worn at all times.
The beginning of the sleep cycle was calculated on the basis of the onset of melatonin release for each student. Melatoni, whose levels start to rise about two hours prior to sleep, influences the sleep-wake cycle by inducing a sleep-promoting effect.
Researchers then looked at the students’ body composition (i.e., fat mass and fat free/muscle mass) and assessed whether how late food was consumed made a difference.
While melatonin onset timing was similar for both lean and nonlean students, those with a higher body fat percentage (8.7 percent higher in women and 10.1 percent higher in men) ate the bulk of their calories one hour closer to melatonin onset.
They also had their last meal at a later time relative to melatonin timing and snacked more as time to sleep approached. Some differences in body fat started to appear with higher calorie intake between 4h before melatonin onset and bed time.
While there is an association between a lean body type and earlier food consumptio, randomized controlled trials (e.g., comparing meal timing of the exact same food close to melatonin onset or when melatonin levels are low) are needed to prove causation.
Overall, this study suggests that we should be vigilant of food intake as time to sleep approaches to limit fat gain.
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