What You Eat, or When You Eat?

A new study from Penn researchers has found a link between fat cell and brain clock molecules. The study found that deleting the ‘clock gene’ Arntl, also known as Bmal1, in fat cells, shift the timing of when mice eat, and makes them obese. These findings may have interesting implications for humans, in adding to our knowledge of the complex causes of obesity.

The researchers explain that when the clock was broken in fat cells, an internal rhythm was disrupted which caused the mice to favor food consumption at a time of day which was different from their usual time – and this could relate to night-time eating in humans. When our daily rhythm is thrown off, changes in metabolism can also occur.  For example, people who work night-shifts have an increased prevalence of obesity and metabolic syndrome, and patients with sleep disorders have a higher risk for developing obesity.

What was particularly interesting in this study, was that the mice became obese without consuming more calories. The study authors say that it was surprising that a relatively modest shift in food consumption into what is normally the ‘rest period’ for mice can encourage the increase in stored calories. Additionally, it was surprising that the molecular clock had the ability to exercise so much power. Traditionally, clocks in peripheral tissues are thought to follow the lead of the “master clock” in a part of the brain called the suprachiasmatic nucleus (SCN). These findings show that the peripheral clocks, instead of just following the “master clock”, may actually be able to influence it.

Another recent experiment by the Salk Institute for Biological Studies gave mice either a standard or high-fat diet, and either granted unrestricted feeding (food availability around the clock) or restricted access (food only available 8 hours per day). The results were unexpected. After 100 days, the mice on the high-fat diets who ate frequently throughout the day gained weight and developed high cholesterol, high blood glucose, liver damage and diminished motor control; however the mice in the time-restricted feeding group weighed 28 percent less and showed no negative health effects despite consuming the same amount of calories from the same fatty food. The researchers propose that restricted meal times may be an underutilized lifestyle change that could assist people in curbing weight gain. It is, though, too early to jump to the conclusion that eating a lot of high-fat food is fine as long as we eat it quickly. Rather, the study demonstrated that daily fasting allows the body to fight unhealthy food to a significant extent, but there are bound to be limits.

Dr. Thomas Brown, bariatric surgeon at the Colorado Bariatric Surgery Institute, commented that “the Salk Institute findings strengthen arguments concerning the powerful impact “lifestyle” has on our likelihood of being obese or potentially losing weight.  Lifestyle changes are pivotal in achieving weight loss, including weight loss associated with bariatric surgery.  Implementing simple lifestyle changes can produce desired results in achieving weight loss goals.”

Dr. Brown explained that for patients, this may be restricting meal times as shown in this study, eating 1 bite every 45 seconds during a meal, or incorporating exercise into our daily routine.  “This study suggests that with simple lifestyle changes you have the power to realize your weight loss goals,” he concluded.

At the very least, the findings of these studies suggest that when we eat is a factor in the obesity epidemic that warrants further consideration.  Dr. Christine Ren Fielding, weight loss surgeon in New York, concluded that “These are very interesting studies which only strengthen the fact that obesity is a complex disease which is affected by many factors, some of which we understand and some that we do not understand yet.  It is not simply a matter of gluttony.”

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Research has shown that people with altered sleep patterns, such as shift workers, are more likely to be obese and develop diabetes or metabolic syndrome. Shift workers are often eating at times when the body is programmed to be sleeping, disrupting their metabolic processes. You can read more about the effects of disrupted sleep here.

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