Nov. 9, 2021 -- Eating a single meal daily may yield longevity and metabolic benefits much like those seen with caloric restriction, according to new findings in mice.
Earlier mouse studies have linked calorie restriction to healthier aging and tied long daily fasting to metabolism changes associated with a longer lifespan. Because mice in those studies usually ate only once a day, the results reflected the effects of both calorie restriction and daily fasting. For the new experiment, published in Nature Metabolism, scientists sought a clearer picture of how fasting on its own might affect health benefits associated with calorie restriction.
To do this, scientists separated male mice into four different diet groups for 4 months, reflecting fasting and calorie restriction together and singly. Mice in the totally unrestricted group ate whatever they wanted whenever they wanted during the day, as a control. A second group represented fasting without calorie restriction, eating as much as possible within 3 hours each day and fasting for the remaining 21 hours.
The other two groups of mice had their calories restricted by about 30%. One group, representing calorie restriction alone, was fed three equally sized meals spread out evenly throughout the day. The other group combined both factors; the mice were trained to eat all of their calorie-restricted food in a single meal at breakfast, with no more food for the rest of the day.
The mice that ate all their food in a single morning meal, whether calorie-restricted or not, had lower blood sugar, better use of fat stores for energy, less frailty as they aged, and longer lifespans.
Although blood sugar levels declined in mice on unfasted calorie restriction, these animals also died about 8 months earlier on average than their calorie-restricted, fasting counterparts.
In other words, these results in mice suggest that a prolonged daily fasting period offers similar benefits to calorie reduction. But whether these patterns apply to people is not known.