When should you eat to manage your weight? Breakfast, not late-night snacks

February 28, 2020

Science Daily/PLOS

The balance between weight gain and weight gain loss is predominantly determined by what you eat, how much you eat, and by how much exercise you get. But another important factor is often neglected... Published February 27 in the open-access journal PLOS Biology, research conducted by Kevin Kelly, Owen McGuinness, Carl Johnson and colleagues of Vanderbilt University, USA shows that it's not just how many calories you eat, but WHEN you eat them that will determine how well you burn those calories.

Your daily biological clock and sleep regulate how the food you eat is metabolized; thus the choice of burning fats or carbohydrates changes depending on the time of day or night. Your body's circadian rhythm has programmed your body to burn fat when you sleep, so when you skip breakfast and then snack at night you delay burning the fat.

The researchers monitored the metabolism of mid-aged and older subjects in a whole-room respiratory chamber over two separate 56-hour sessions, using a "random crossover" experimental design. In each session, lunch and dinner were presented at the same times (12:30 and 17:45, respectively), but the timing of the third meal differed between the two halves of the study. Thus in one of the 56-hour bouts, the additional daily meal was presented as breakfast (8:00) whereas in the other session, a nutritionally equivalent meal was presented to the same subjects as a late-evening snack (22:00). The duration of the overnight fast was the same for both sessions.

Whereas the two sessions did not differ in the amount or type of food eaten or in the subjects' activity levels, the daily timing of nutrient availability, coupled with clock/sleep control of metabolism, flipped a switch in the subjects' fat/carbohydrate preference such that the late-evening snack session resulted in less fat burned when compared to the breakfast session. The timing of meals during the day/night cycle therefore affects the extent to which ingested food is used versus stored.

This study has important implications for eating habits, suggesting that a daily fast between the evening meal and breakfast will optimize weight management.

https://www.sciencedaily.com/releases/2020/02/200228125230.htm

When You Eat Matters, Not Just What You Eat

May 17, 2012

Science Daily/Cell Press

When it comes to weight gain, when you eat might be at least as important as what you eat. That's the conclusion of a study reported in the Cell Press journal Cell Metabolism published early online on May 17th.

When mice on a high-fat diet are restricted to eating for eight hours per day, they eat just as much as those who can eat around the clock, yet they are protected against obesity and other metabolic ills, the new study shows. The discovery suggests that the health consequences of a poor diet might result in part from a mismatch between our body clocks and our eating schedules.

"Every organ has a clock," said lead author of the study Satchidananda Panda of the Salk Institute for Biological Studies. That means there are times that our livers, intestines, muscles, and other organs will work at peak efficiency and other times when they are -- more or less -- sleeping.

Those metabolic cycles are critical for processes from cholesterol breakdown to glucose production, and they should be primed to turn on when we eat and back off when we don't, or vice versa. When mice or people eat frequently throughout the day and night, it can throw off those normal metabolic cycles.

"When we eat randomly, those genes aren't on completely or off completely," Panda said. The principle is just like it is with sleep and waking, he explained. If we don't sleep well at night, we aren't completely awake during the day, and we work less efficiently as a consequence.

To find out whether restricted feeding alone -- without a change in calorie intake -- could prevent metabolic disease, Panda's team fed mice either a standard or high-fat diet with one of two types of food access: ad lib feeding or restricted access.

The time-restricted mice on a high-fat diet were protected from the adverse effects of a high-fat diet and showed improvements in their metabolic and physiological rhythms. They gained less weight and suffered less liver damage. The mice also had lower levels of inflammation, among other benefits.

Panda says there is reason to think our eating patterns have changed in recent years, as many people have greater access to food and reasons to stay up into the night, even if just to watch TV. And when people are awake, they tend to snack.

The findings suggest that restricted meal times might be an underappreciated lifestyle change to help people keep off the pounds. At the very least, the new evidence suggests that this is a factor in the obesity epidemic that should be given more careful consideration.

http://www.sciencedaily.com/releases/2012/05/120517132057.htm

That Late-Night Snack: Worse Than You Think

September 7, 2009

Science Daily/Northwestern University

Eat less, exercise more. Now there is new evidence to support adding another "must" to the weight-loss mantra: eat at the right time of day.

A Northwestern University study has found that eating at irregular times -- the equivalent of the middle of the night for humans, when the body wants to sleep -- influences weight gain. The regulation of energy by the body's circadian rhythms may play a significant role. The study is the first causal evidence linking meal timing and increased weight gain.

"One of our research interests is shift workers, who tend to be overweight," said lead author Deanna M. Arble, a doctoral student in Turek's lab. "Their schedules force them to eat at times that conflict with their natural body rhythms. This was one piece of evidence that got us thinking -- eating at the wrong time of day might be contributing to weight gain. So we started our investigation with this experiment."

Simply modifying the time of feeding alone can greatly affect body weight, the researchers found. Mice that were fed a high-fat diet during normal sleeping hours gained significantly more weight (a 48 percent weight increase over their baseline) than mice eating the same type and amount of food during naturally wakeful hours (a 20 percent increase over their baseline). There was no statistical difference between the two groups regarding caloric intake or the amount of activity.

http://www.sciencedaily.com/releases/2009/09/090903110800.htm

Mothers' sleep, late in pregnancy, affects offspring's weight gain as adults

May 16, 2014

Science Daily/University of Chicago Medical Center

Poor-quality sleep during the third trimester of pregnancy can increase the odds of weight gain and metabolic abnormalities in offspring once they reach adulthood. The effects, caused by epigenetic modifications, impose lasting consequences on the next generation.

The researchers linked the excess weight and changes in metabolism to epigenetic modifications that reduce expression of the gene for adiponectin -- a hormone that helps regulate several metabolic processes, including glucose regulation. Lower levels of adiponectin correlate with increased body fat and reduced activity.

"Disrupted sleep is a common problem during the final trimester of a pregnancy," said study director, sleep specialist David Gozal, MD, the Herbert T Abelson professor of pediatrics at the University of Chicago. "For some women, sleep fragmentation, especially sleep apnea, can be profound. We wanted to devise a system that enabled us to measure the potential impact of fragmented sleep on the fetus, which is uniquely susceptible so early in life."

Adiponectin is usually a "beneficial hormone," Gozal said. "It can reduce cholesterol, make you more sensitive to insulin, protect your heart." As adiponectin levels in adults go up, body-fat percentage tends to go down. Expression of the adiponectin gene was reduced in the offspring of sleep-fragmented mothers, especially in their visceral fat cells.

A closer look revealed epigenetic changes, such as methylation and histone modification, which shut down selected genes, often in response to environmental stresses.

"We found that the offspring of sleep-deprived mothers had largely inactivated AdipoQ, the adiponectin gene," Gozal said. "Such changes may affect other genes as well; we haven't studied all the potential targets yet. Even so, this is the first example of a perturbation during pregnancy that translates into a genetic risk, in midlife, for the next generation."

"This is kind of scary," he added. "Will this generation, the sons of sleep-deprived mice, who are already at increased risk for metabolic syndrome and type 2 diabetes, transmit this inherited risk, perhaps compounded by new stresses, to their offspring?"

http://www.sciencedaily.com/releases/2014/05/140516092305.htm