Later circadian timing of food intake is associated with increased body fat

We often hear the advice that we shouldn’t eat close to bed-time, and that such habits can lead to weight gain, heart-burn, and other problems.

Studies looking at the relationship between the timing of food intake vs. sleep and its effect on weight gain are rare, at least controlled studies are. 

Most of the studies on the subject in the past have tended to be “observational” in nature: in other words, they observe a group of people, and try to see whether those of have dinner “late” are also “overweight”. And often times the conclusion is clear: late eaters have more bodyfat.

However observational studies are inherently unreliable because they often do not control of other confounding variables.

For example: if we’re just observing people who eat dinner late, those people may have an overall less healthy lifestyle for example: they are also more likely to smoke, drink, not exercise, and not get enough sleep. So which of these factors contributes the most to the weight gain? It’s hard to really tell.

This is why this new study from the American Journal of Clinical Nutrition is so important: it observed a group of 110 young individuals in a semi-controlled environment and also recorded their other lifestyle habits, including exercise, smoking, drinking, etc.

What they discovered was that those people (especially women) who ate most of their calories within 1.1 hours of their Melatonin Onset were significantly more overweight than people who ate earlier, regardless of their other lifestyle habits (exercise, etc).

But what is Melatonin Onset??

Well Melatonin Onset is when your body starts to produce Melatonin Hormone (sleep hormone) to prepare you for bed, and this usually happens around 2 to 2.5 hours before you go to bed.

This means that the “leanest” people were those who ate their dinner 3.1 to 3.6 hours before bed, again, regardless of exercise and other habits.