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Even a 12 Hour Fast May Be Good For Us

Evidence is growing that "mini-fasts" (when food is not eaten) for as little as a 12 hour time period every day is good for the body and may help with weight control. For example, eat supper and then nothing more (but water is OK) till the next day's breakfast - instant 12 hour fast! The second study posted liked a 16 hour mini-fast. From the NY Times:

A 12-Hour Window for a Healthy Weight

Scientists, like mothers, have long suspected that midnight snacking is inadvisable. But until a few years ago, there was little in the way of science behind those suspicions. Now, a new study shows that mice prevented from eating at all hours avoided obesity and metabolic problems — even if their diet was sometimes unhealthful.

Researchers at the Salk Institute for Biological Studies in San Diego and elsewhere began experimenting with the eating patterns of laboratory mice in a previous study. On that occasion, some mice consumed high-fat food whenever they wanted; others had the same diet but could eat only during an eight-hour window. None exercised. The mice that ate at all hours soon grew chubby and unwell, with symptoms of diabetes. But the mice on the eight-hour schedule gained little weight and developed no metabolic problems. Those results were published in 2012.

For the new study, which appeared in the journal Cell Metabolism in December, Salk scientists fed groups of adult males one of four diets: high-fat, high-fructose, high-fat and high-sucrose, and regular mouse kibble. Some of the mice in each dietary group were allowed to eat whenever they wanted throughout their waking hours; others were restricted to feeding periods of nine, 12 or 15 hours. The caloric intake for all the mice was the same.

By the end, the mice eating at all hours were generally obese and metabolically ill, reproducing the results of the earlier study. But those mice that ate within a nine- or 12-hour window remained sleek and healthy, even if they cheated occasionally on weekends. What’s more, mice that were switched out of an eat-anytime schedule lost some of the weight they had gained.

“Time-restricted eating didn’t just prevent but also reversed obesity,” says Satchidananda Panda, an associate professor at the Salk Institute who oversaw the studies. “That was exciting to see.” Mice that consumed regular kibble in fixed time periods also had less body fat than those that ate the same food whenever they chose.

Precisely how a time-based eating pattern staved off weight gain and illness is not fully understood, but Dr. Panda and his colleagues believe that the time at which food is eaten influences a body’s internal clock. “Meal times have more effect on circadian rhythm than dark and light cycles,” Dr. Panda says. And circadian rhythm in turn affects the function of many genes in the body that are known to involve metabolism.

To date, Dr. Panda’s studies have been conducted with only mice, but he says the results seem likely to apply to humans. The upshot: Contain your eating to 12 hours a day or less. And pay attention to when you begin. The clock starts, Dr. Panda says, with “that first cup of coffee with cream and sugar in the morning.”

Another article also liked an "energy restriction period" (mini-fast), but they liked a 16 hour non-eating period.Here is the complete abstract (summary) of the article in Proceedings of the National Academy of Sciences USA,Nov. 25, 2014:

Meal frequency and timing in health and disease.

Although major research efforts have focused on how specific components of foodstuffs affect health, relatively little is known about a more fundamental aspect of diet, the frequency and circadian timing of meals, and potential benefits of intermittent periods with no or very low energy intakes. The most common eating pattern in modern societies, three meals plus snacks every day, is abnormal from an evolutionary perspective. Emerging findings from studies of animal models and human subjects suggest that intermittent energy restriction periods of as little as 16 h can improve health indicators and counteract disease processes. The mechanisms involve a metabolic shift to fat metabolism and ketone production, and stimulation of adaptive cellular stress responses that prevent and repair molecular damage. As data on the optimal frequency and timing of meals crystalizes, it will be critical to develop strategies to incorporate those eating patterns into health care policy and practice, and the lifestyles of the population.