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Salk study may offer drug-free intervention to prevent obesity and diabetes

liver tissue

These images of liver tissue show the difference in fat accumulation between two groups of mice fed a high-fat diet. A mouse allowed to eat 24 hours a day (left) had much higher levels of liver fat (white) than one restricted to an 8-hour daily feeding window (right).

It turns out that when we eat may be as important as what we eat. Scientists at Salk 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.

In a paper published in Cell Metabolism, a team led by Satchidananda Panda reported that mice limited to eating during an eight-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.

"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. "Our findings, however, suggest that regular eating times and fasting for a significant number of hours a day might be beneficial to our health."

Panda's team fed two sets of mice that shared the same genes, gender and age a diet comprising 60 percent 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 percent 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 timerestricted feeding group weighed 28 percent 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.

"The take-home message," says Panda, "is that eating at regular times during the day and overnight fasting may prove to be beneficial, but we will have to wait for human studies to prove this."