Got the night munchies? Beware diabetes and heart disease



How many of us can honestly say that we've never raided the fridge at 3 a.m., egged on by an uncontrollable hunger for ice-cream? Doing this once or twice is fine, but new research says that if you make this a habit, you could be in trouble.

Late-night snacking is a strange habit, and there are various theories as to why so many of us are inclined to raid our cupboards and fridges past our bedtime. One study has suggested that our craving for certain types of food — those rich in starch, salt, and sugars — late in the evening may be explained by our ancestors' needs.

The study authors explained that early humans did not know when and where their next meal would come from, so binge eating late in the day where possible allowed their bodies to store the energy needed for survival.

But now, our snacks are driven more by pleasure than by necessity, so their effects are much less wholesome. Researchers agree that caving in to your munchies and eating late in the evening leads to negative health outcomes, such as a heightened risk of obesity.

This may not only be tied to the snacks' nutritional value, though; it might also be linked to how our bodies are programmed to work, and how our circadian — or internal — clocks function. Our bodies are adjusted to the natural day-night cycle, and so they tell us when we should eat, sleep, and be active.

If the circadian clock is ignored, health and well-being are also impacted. For instance, it was found that eating outside the normal waking and activity hours may cause excess weight gain.

And now, emerging research from the National Autonomous University of Mexico in Mexico City suggests that late-night eaters may also be predisposed to diabetes and heart disease.

The study, which was led by Prof. Ruud Buijs, suggested that "upturning" eating habits dictated by our biological clocks can lead to heightened blood fat, or triglyceride, levels. This, in turn, is tied to metabolic and heart diseases.

The study results were published yesterday in the journal Experimental Physiology.



Avoid 'eating at times when we should sleep'

Prof. Buijs and team led a series of experiments in rats, focusing on blood triglyceride levels and the impact of the circadian clock on their fluctuation.

Following their tests, the researchers noted that when fed at the beginning of their normal rest interval, the animals displayed substantially higher triglyceride levels.

If fed at the start of the period when their bodies were normally fully active, however, the rats did not experience the same sharp increase in blood fats.



Following these experiments, the researchers chose to remove the part of the animals' brains that is largely responsible for regulating circadian rhythm, so that they could see whether that would impact the results.

In the brains of humans and other mammals, the suprachiasmatic nucleus (SCN) is tasked with keeping body clocks up and running and in sync with each other.

After the scientists removed the SCN from the rats' brains, they noticed that no matter when the animals were fed, their triglyceride levels no longer fluctuated.



So, the researchers concluded that if we "mess" with our normal circadian rhythm on a regular basis — for instance, by eating late at night — the way in which our bodies respond could be affected. In the case of heightened triglyceride levels, it might give rise to diabetes and cardiovascular disease.

Prof. Buijs and colleagues warn that these dangerous inverted patterns are now fairly common "in westernized countries ([where] late-night dinners [are habitual]) and in night workers." So, night owls, beware: it's best to eat early, and not to cave in to the midnight munchies.

"The fact that we can ignore our biological clock," adds Prof. Buijs, "is important for survival; we can decide to sleep during the day when we are extremely tired or we run away from danger at night."

"However, doing this frequently — with shift work, jet lag, or staying up late at night — will harm our health in the long-term especially when we eat at times when we should sleep." Prof. Ruud Buijs