A recent study published in "Science Alert" reveals that eating later in the day can directly impact our biological weight regulation through three main mechanisms: the number of calories we burn, our hunger levels, and how our bodies store fat. Given that obesity now affects hundreds of millions of people worldwide, this insight offers a relatively simple approach to reducing the risk of obesity—just by eating our meals a few hours earlier. Previous studies had already identified a link between meal timing and weight gain, but here researchers aimed to closely examine this correlation, as well as uncover the underlying biological reasons.
Neuroscientist Frank Scheer from Brigham Hospital in Boston stated, "We wanted to test the mechanisms that might explain why increased late-night eating raises obesity risk. Previous research we've conducted indicated that late eating is associated with increased obesity risk, higher body fat, and lower success in weight loss. We wanted to understand why." The tightly controlled research included 16 participants with a body mass index (BMI) within the overweight or obese range. Each volunteer underwent two different six-day trials, with their sleep and meal intake controlled beforehand, and with several weeks between each test.
In one experiment, participants adhered to a strict schedule of three meals per day at regular times—breakfast at 9 AM, lunch at 1 PM, and dinner around 6 PM. In the second experiment, the three meals were shifted later (the first around 1 PM and the last around 9 PM). Through blood samples, survey questions, and other measurements, the team made several observations: when eating later, leptin levels—the hormone that tells us when we are full—were lower over 24 hours, suggesting that participants may have felt hungrier. Furthermore, calories were burned at a slower rate. Tests also showed that the gene expression in fatty tissues—which affects how the body stores fat—was elevated in processes that build fatty tissue while reducing the breakdown of fat.
Scheer remarked, "We isolated these effects by controlling for confounding variables like calorie intake, physical activity, sleep, and light exposure, but in real life, many of these factors may also be affected by meal timing." Of course, obesity can lead to other health issues, including diabetes and cancer, so finding ways to prevent its development will make a significant difference in global health. What this study demonstrates is that eating earlier in the day can influence three key drivers of how our bodies balance energy and the risks of later obesity—a change that might be easier for some people to manage rather than sticking to a strict diet or exercise regime.
In the future, the team hopes to see research that includes more women (only 5 out of 16 volunteers were women in this case), as well as studies analyzing how changes in sleep timing relative to meal timing can also affect these processes.
