Skipping breakfast is not a good diet idea. An energy deficit in the morning hours can trigger migraine attacks, as studies have shown. But eating late can also lead to hunger and obesity. A new study in Cell Metabolism (2022; DOI: 10.1016/j.cmet.2022.09.007) shows that it is not just increased feelings of hunger that can occur throughout the day. Energy consumption is also reduced. In the end, the fat stores fill up. The result is excess weight. The explanation for the failure of the breakfast skipping diet is now provided by a cross-over study carried out by sleep researchers at Harvard Medical School in Boston.

While common healthy eating mantras discourage late-night snacking, few studies have comprehensively examined the simultaneous effects of late eating on the three key players in weight regulation and therefore obesity risk:

  • the regulation of calorie intake,
  • the number of calories burned and
  • the molecular changes in fatty tissue.

The new study by researchers at Harvard Medical School found that the timing of eating has a significant impact on energy expenditure, appetite and molecular processes in adipose tissue.

"We wanted to examine the mechanisms that might explain why late eating increases the risk of obesity," said lead author Frank Scheer, professor of medicine and director of the Medical Chronobiology Program in the Division of Sleep and Circadian Disorders at Brigham and Women's Hospital .

“Previous research by us and others has shown that late eating is associated with increased risk of obesity, increased body fat and poorer weight loss success. We wanted to understand why,” he said.

“In this study, we asked whether the time at which we eat matters, all else being equal,” said lead author Nina Vujović, a researcher in the Medical Chronobiology Program.

"And we found that eating four hours later makes a significant difference in how we feel hungry, the way we burn calories after eating, and the way we store fat."

Vujović, Scheer and their team examined 16 patients with a body mass index in the overweight or obese range. Each participant completed two laboratory protocols: one with a strictly scheduled early meal and the other with the same meals each eaten approximately four hours later in the day.

During the last two to three weeks before beginning each laboratory protocol, participants maintained consistent sleep and wake times, and during the last three days before entering the laboratory, they strictly adhered to identical diets and meal schedules at home.

In the laboratory, participants regularly documented their hunger and appetite, took small blood samples frequently throughout the day, and had their body temperature and energy expenditure measured.

To measure how meal time affects the molecular pathways involved in adipogenesis, i.e. how the body stores fat, researchers took biopsies of adipose tissue from a subset of participants during laboratory testing, both in the early and late eating protocols to allow comparison of gene expression patterns/values ​​between these two eating conditions.

The results showed that eating later had profound effects on hunger and the appetite-regulating hormones leptin and ghrelin, which influence our desire to eat. In particular, levels of the hormone leptin, which signals satiety, were lower under the late eating conditions than under the early eating conditions over 24 hours.

When participants ate later, they also burned fewer calories and had gene expression in adipose tissue indicating increased adipogenesis and reduced lipolysis, which promote fat growth.

These results suggest converging physiological and molecular mechanisms underlying the association between late eating and increased obesity risk.

Vujović explained that these results are not only consistent with a variety of research suggesting that eating later increases the likelihood of developing obesity, but that they also shed new light on how this might happen.

Effects on energy metabolism are important. Both groups consumed the same amount of calories. In late eaters, these were stored more in the fatty tissue.

An early and good breakfast combats hunger during the day, reduces the risk of being overweight and, as other studies have shown, can also help reduce the risk of migraines.

Source:

Vujović N, Piron MJ, Qian J, Chellappa SL, Nedeltcheva A, Barr D, Heng SW, Kerlin K, Srivastav S, Wang W, Shoji B, Garaulet M, Brady MJ, Scheer FAJL.
Late isocaloric eating increases hunger, decreases energy expenditure, and modifies metabolic pathways in adults with overweight and obesity. Cell Metab. 2022 Oct 4;34(10):1486-1498.e7. doi: 10.1016/j.cmet.2022.09.007. PMID: 36198293. https://doi.org/10.1016/j.cmet.2022.09.007