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News and Research: Meal timing matters, earlier may be better

Late isocaloric eating increases hunger, decreases energy expenditure, and modifies metabolic pathways in adults with overweight and obesity  Cell Metabolism, October 2022

Researchers tackled the question of whether the time of day matters in time-restricted eating — in humans. :-)

Using a crossover study, the researchers tested out the idea of whether eating the same number of calories earlier in the day would differ from eating them later in the day.

The participants were in a controlled setting where meals were provided, temperatures monitored, and variables controlled for the two different weeks of eating trials.

For one week, participants ate breakfast around 8, lunch around 1 pm, and dinner around 5 pm. In contrast, for the second week (separated by a washout period), the participants ate lunch at 1, dinner at 5, and a large snack at 9 pm.

Sleep timing was held the same for both weeks –around midnight to 8 am.

Eating later caused increased hunger, which correlated to significant changes in ghrelin and leptin levels.

What I found fascinating was that eating later causes a decrease in overall energy expenditure for the day, which was calculated to mean expending 59 fewer kcal per day. Not only was overall movement decreased with late eating, but core body temperature for the day was lower (expending fewer calories).

Gene expression for circadian-related genes was changed as well as the downregulation of some genes related to lipid breakdown.


Related Genetic Lifehacks article Circadian rhythm genes and weight

About the Author:
Debbie Moon is the founder of Genetic Lifehacks. Fascinated by the connections between genes, diet, and health, her goal is to help you understand how to apply genetics to your diet and lifestyle decisions. Debbie has a BS in engineering from Colorado School of Mines and an MSc in biological sciences from Clemson University. Debbie combines an engineering mindset with a biological systems approach to help you understand how genetic differences impact your optimal health.