When You Eat May Be As Important As What You Eat

When we eat during the day matters more than previously realized.

Most of us are aware that the rhythms of our body are connected to the rhythms of the Earth’s rotation. We know that when a person’s sleep cycle is out of sync with the circling of our planet, he or she is more susceptible to heart disease, diabetes, depression and myriad of other ailments.

Now, scientists have discovered it is not only disrupted sleep patterns that cause physical and mental problems. Health problems, especially metabolic disorders, also occur when the timing of our food consumption is out of sync with Earth’s diurnal movements.

Our Body’s Complex Clock System

Until the late 1990s, the human circadian clock was thought to be regulated by a bunch of neurons - about 20,000 of them - located within the hypothalamus. This gaggle of neurons is called the suprachiasmatic nucleus (SCN). It was believed that the behavioral rhythms of our entire body followed the SCN’s lead - that is, until researchers discovered the existence of peripheral gene clocks.

Our peripheral tissues contain tiny time pieces, or oscillators, that work to adjust the daily rhythmic actions of our organs. The peripheral oscillators are guided by the SCN, and the whole clock system is influenced by environmental cues about the time of day. The SCN is primarily influenced or cued by light. Our peripheral clocks are cued by other inputs, such as food consumption.

Eating, Timing, and Health

Many peripheral oscillators found in the gastrointestinal tract are highly sensitive to when we eat. However, the SCN is much less affected by ingesting food. This led scientists to hypothesize that certain health problems might be caused by a disrupted link between the SCN and peripheral clocks when people mistime their eating.

For instance, light may be cuing an individual’s brain that it is time to sleep and for the body to burn fats. However, if the individual is eating at that hour, the body will also be cued that it is time to store fats. So, there is an uncoupling of the SCN and peripheral rhythms.

“We suspect that eating at the inappropriate time of the day ends up with peripheral clocks - in the liver, in fat, in the pancreas, in the muscle - being in a phase which is now different from the SCN,” says University of Pennsylvania researcher Georgios Paschos.

Studies have shown that the effect of gene clocks that are cued by mistimed eating primarily impact glucose metabolism, fatty acid synthesis and breakdown, cholesterol production and liver function.

Eating and Evolution

Our metabolism and our biological clock perform a continuous dance that is timed to the Earth’s rotation. The modern world full of all-night restaurants, artificial light and around-the-clock TV and computer entertainment can put these dancers out of sync.

It is possible, though not proven, that living a lifestyle outside the natural cycle of day and night is at least partly responsible for the sharp increase in obesity and metabolic disorders in developed countries. “Like many evolutionary arguments, it’s hard to prove,” says researcher M.A. Lazar. “But otherwise it’s hard to imagine why else we would need things so tightly linked to the Earth’s rotation.”

Source: The Scientist