It's time to change your daily routine: Late-night dinners can increase the risk of obesity, says study

Is eating late at night an everyday affair? Do you get peckish at midnight? It may be time to reconsider indulging in delicious food during late hours. A study said that late-night dinners can increase the chances of obesity.

India's population is rapidly growing toward being overweight and obese. A 2019 Global Burden of Disease (GBD) study revealed that obesity was the primary cause of premature death in 5.02 million people.

According to the 2022 National Family Health Survey, nearly one in every four Indians is overweight. Being overweight and obese are calculated using a simple measurement tool - Body Mass Index (BMI). People who have a BMI score of more than 30 are considered obese, and an individual between 25 and 29.9 is overweight.


BMI is calculated by dividing weight (in kilograms) by the square of height (in meters).
BMI = kg/m2

Published in Cell Metabolism, the Harvard Medical School researchers found that the time we eat significantly impacts our energy levels, appetite, and changes in adipose (fat) tissue - further leading to a high chance of obesity.

"We wanted to test the mechanisms that may explain why late eating increases obesity risk," explained senior author Frank A. J. L. Scheer, PhD, Director of the Medical Chronobiology Program in Brigham's Division of Sleep and Circadian Disorders.

The first author of the study, Nina Vujovic, a PhD and researcher in the Medical Chronobiology Program at Brigham's Division of Sleep and Circadian Disorders, said, "And we found that eating four hours later makes a significant difference for our hunger levels, the way we burn calories after we eat, and the way we store fat."

In short, consuming meals at 10 PM instead of 6 PM can increase hunger and cut the calories burned.

For the study, the experts studied 16 patients with high 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 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. Notably, these findings convey converging physiological and molecular mechanisms underlying the correlation between late eating and increased obesity risk.

Obesity is known as one of the major risk factors for lifestyle conditions like type 2 diabetes and cardiovascular diseases. It can also cause cognitive decline and lead to neurological diseases such as Alzheimer’s disease.

It is advisable to not eat right before hitting the bed.