Are late-night meals always bad for your waistline?

Eating after 8pm has been associated with weight gain. Some argue that our bodies have evolved to be active during daylight, and daytime is the best time to exercise, to think and to digest food, while nighttime is best for sleep and fasting. Messing with that natural rhythm increases the risk of obesity and also of diseases such as diabetes and heart disease.

But what if 8pm is the middle of your day?

Many of today’s teens and college-aged kids are creatures of the night. They live in social jetlag. Weekend breakfast is an afternoon affair, typical dinner can only keep them going for so long, and they therefore eat a very late additional meal or snack. When your day begins at 12pm and ends at 3am, midnight meals are almost called for.

When the internal clock shifts in such a way do late meals still affect weight gain?

Social jetlag makes mealtimes relative

A new study, published in the American Journal of Clinical Nutrition looked not only at clock time, but also at the circadian timing – the body’s internal clock – and at body fat.

The study recruited 110 18-22 year olds, followed their sleep and wakefulness, regular daily routines, and all food intake using a time-stamped-picture app that was followed by nutritional analysis of the meals and snacks. On top of that, their melatonin release patterns were assessed in the lab – melatonin release above a certain concentration level is an established marker of our internal clocks’ night onset.

The researchers found that lean and overweight students had similar mealtimes if you looked at the clock.

But when you looked at these young people’s internal clocks it was a whole other story: lean people finished most of their daily calories 1.1 hours earlier according to the onset of their personal nighttime, as determined by their melatonin release. Those with more body fat ate more of their calories later according to their internal biological clock.

In this study, the biological clock mattered, not the actual time of day.

Which makes sense.

If you fly from San Francisco to New York in the morning, and get really hungry at 10pm Eastern Time, it’s hardly a surprise: This is a very ordinary time to eat dinner in Pacific Time. For many College kids the internal clock strikes 8pm at midnight, and by their own clock and metabolic point of view they’re not eating a midnight snack at all – this is just dinner.

Eat and drink better at night

This study suggests that the actual time of day and the setting of the sun matter less than what your internal clock is showing. The no-food-after-8pm is advice that doesn’t jibe with many young people’s sleep-wake routines.

Instead, I recommend stopping eating 2 hours before you go to sleep.

If you find yourself hungry at night, try hydration. People who feel hungry sometimes are actually low on fluids; they’re a little thirsty, and water or a non-sweetened no-calorie drink can alleviate this craving for midnight snacks. Drink, wait a bit, and see if the hunger subsides.

If you truly are hungry, do eat; what you eat matters more than the meal timing. Instead of highly processed, easy to grab junk food, eat a nutritious meal or snack, or another serving of fruit or nuts. One of the problems with late-night eating is that there’s no game plan, not many healthy options, and when you’re hungry at night your defenses are down. If you know you’re prone to late night eating, plan for it and have a few healthy options handy.

Dr. Ayala