Life is all about the timing. It’s a metaphor most of us have intuitively grasped since our formative, single-digit years, yet not really applied scientifically in everyday living. All too often, shifting goalposts shift daily timelines for eating and sleeping. The result isn’t always a “health” trophy at the finishing line.
Increasingly, science is telling us that our body clock—the 24-hour circadian rhythm that coordinates our internal sleep-and-wake cycle with the external dark-and-light cycle—may hold the key to many health disorders, including depression, sleep hygiene, risks of cancer and cardiac diseases, and weight gain.
Eating irregularly adds up
Beginning with the assumption that circadian clocks influence fitness traits, scientists have discovered, through several associations in humans, as well as animal models, that the time of eating is related to weight gain. Last week, scientists reported in the journal Obesity that they have for the first time found “causal” evidence that weight gain may be influenced by meal timing. That is to say, eating at irregular hours may contribute to weight gain.
This isn’t hard to believe: Dieters are often warned against late-night eating. Studies on non-breakfast eaters and those with night-eating syndrome are consistent with the observation that the time of food intake is a determining factor in weight gain. Recent work has also shown that the body’s internal clock regulates energy use, which suggests the timing of meals could also have a role in balancing the calories one burns. Eat more at a low-ebb time, and you can’t help but store it.
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Sleep and meals don’t mix
The authors of the study that appeared in Obesity, Fred W. Turek and Deanna Arble from the Centre for Sleep and Circadian Biology, Northwestern University, Illinois, say the field is not yet advanced enough to prescribe appropriate eating times for each individual, but “we can at least say that humans should avoid eating during their normal sleeping phase, because this could lead to increased weight gain”.
That doesn’t mean we lose sight of the calories which, if eaten in excess even at the right time, will add fat to the frame. Similarly, if you are eating small meals for dinner, the overall caloric intake is anyway lowered and may have a greater effect than timing alone.
However, the recent study, Arble says, provides a significant clue in cases where people aren’t consuming excess calories, but are still gaining weight.
Liquor resets the rhythm
Science may be stumbling upon the adaptive significance of the body clock now, but evolutionarily, circadian systems were set in motion when life first began. Over the millennia, these got coupled with the astronomical cycles behind earth’s climate, seasons, sunrise and sunset. Now, fundamental relationships between the body’s timekeeper and its overall health are emerging. For instance, last week, scientists reported in the American Journal of Physiology that alcohol consumption affects the body’s master clock, which controls our circadian rhythm.
For humans (such causal studies are difficult to do in humans and are often done in animal models), this could mean that people who drink late into the night may have trouble keeping their circadian clocks in sync with daylight over the next 24 hours. Once that sync snaps, metabolic mayhem begins.
Watching the clock
The caveat is that most of such studies are suggestive; they can’t be conclusive because they haven’t been replicated at population levels, accounting for genetic variations. Moreover, circadian and feeding rhythms could vary with race, ethnicity, even culture.
The idea here is to alert you to the mental and physical connection to feeding, drinking and the circadian clock, but not have you seal your mind with an acrylic topcoat.
The writer is Mint’s deputy bureau chief in Bangalore.
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