Eating late increases hunger and decreases calories burned

October 11, 2022
Eating late increases hunger and decreases calories burned

Researchers from Brigham and Women’s Hospital (BWH) found that late eating increases our appetite and obesity risk, and also affects our energy expenditure and molecular pathways in adipose tissue (fat). Studies have highlighted the simultaneous effects of late eating on the three main players in body weight regulation and obesity risk: regulation of calorie intake, the number of calories burnt, and molecular changes in fat tissue. 

“…late eating is associated with increased obesity risk, increased body fat, and impaired weight loss success. We wanted to understand why,” said Dr. Frank Scheer, Director of the Medical Chronobiology Program in the Brigham’s Division of Sleep and Circadian Disorders. 

According to the latest research, eating later – by four hours – makes a significant difference for our hunger levels, the way we burn calories after we eat, and the way we store fat, revealed Nina Vujovic, a postdoctorate researcher in the same Program at BWH. 

Vujovic, Scheer, and their team studied 16 patients with a body mass index (BMI) in the overweight or obese range. Each participant completed two laboratory protocols: one with a strictly scheduled early meal schedule, and the other with the exact same meals, each scheduled about four hours later in the day. In the last two to three weeks before starting each of the in-laboratory protocols, participants maintained fixed sleep and wake schedules, and in the final three days before entering the laboratory, they strictly followed identical diets and meal schedules at home.  

In the lab, participants regularly documented their hunger and appetite, provided frequent small blood samples throughout the day, and had their body temperature and energy expenditure measured. To measure how eating time affected molecular pathways involved in adipogenesis, or how the body stores fat, investigators collected biopsies of adipose tissue from a subset of participants during laboratory testing in both the early and late eating protocols, to enable comparison of gene expression patterns/levels between these two eating conditions. 

Results revealed that eating later had profound effects on hunger and appetite-regulating hormones leptin and ghrelin, which influence our drive to eat. Specifically, levels of the hormone leptin, which signals satiety, were decreased across the 24 hours in the late eating condition compared to the early eating conditions. When participants ate later, they also burned calories at a slower rate and exhibited adipose tissue gene expression towards increased adipogenesis and decreased lipolysis, which promote fat growth.  

The findings convey converging physiological and molecular mechanisms underlying the correlation between late eating and increased obesity risk. 

By tightly controlling for behavioural and environmental factors such as physical activity, posture, sleep, and light exposure, the researchers were able to detect changes in the different control systems involved in energy balance, a marker of how our bodies use the food we consume – however, in real life, many of these factors may themselves be influenced by meal timing, the researchers note. 

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Category: Education, Features, Uncategorized

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