We always focus on what we’re eating but when it comes to weight gain, according to a recent study reported in the Cell Press journal Cell Metabolism, when we eat might be just as important.
Scientists at the Salk Institute for Biological Studies have found that regular eating times and extending the daily fasting period may override the adverse health effects of a high-fat diet and prevent obesity, diabetes and liver disease in mice.
The researchers fed two sets of mice, which shared the same genes, gender and age, a diet comprising 60% of its calories from fat (like eating potato chips and ice-cream for all your meals). One group of mice could eat whenever they wanted, consuming half their food at night (mice are primarily nocturnal) and nibbling throughout the rest of the day. The other group was restricted to eating for only eight hours every night; in essence, fasting for about 16 hours a day. Two control groups ate a standard diet comprising about 13% of calories from fat under similar conditions.
After 100 days, the mice who ate fatty food frequently throughout the day gained weight and developed high cholesterol, high blood glucose, liver damage and diminished motor control, while the mice in the time-restricted feeding group weighed 28% less and showed no adverse health effects despite consuming the same amount of calories from the same fatty food. Further, the time-restricted mice outperformed the ad lib eaters and those on a normal diet when given an exercise test.
In other words, mice limited to eating during an 8-hour period are healthier than mice that eat freely throughout the day, regardless of the quality and content of their diet.
The study sought to determine whether obesity and metabolic diseases result from a high-fat diet or from disruption of metabolic cycles.
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.
"It's a dogma that a high-fat diet leads to obesity and that we should eat frequently when we are awake," says Satchidananda Panda, an associate professor in the Regulatory Biology Laboratory and senior author of the paper. "Our findings, however, suggest that regular eating times and fasting for a significant number of hours a day might be beneficial to our health."
Every organ has a clock. 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.
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.
"The focus has been on what people eat," Panda said. "We don't collect data on when people eat."
The Iron You