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Eating at the wrong times: bad and unsuitable

Eating at the wrong times is tied to such profound and negative effects on our bodies

According to Satchidananda Panda of the Salk Institute, "we are very different animals between the day and night."

Peripheral clocks

researchers discovered that the SCN is not the body's only timepiece. Additional oscillators in the peripheral tissues help adjust the daily rhythmic functions of organs. (See illustration here.) In the gut, for instance, intestinal motility and absorption differ depending on the time of day. Like all of the body's clocks, these rhythms are guided by clock genes that operate in a transcriptional feedback loop. Transcription factors such as CLOCK and BMAL1 activate the expression of a large number of genes, including Period and Cryptochrome, whose proteins, in turn, inhibit CLOCK and BMAL1, causing daily oscillations in their expression.

Circadian clocks in the periphery are guided by the SCN, and all of the clocks are vulnerable to the influence of zeitgebers (from the German for "time giver"), environmental stimuli that tell the body what time it is. The SCN's primary zeitgeber is light. Clocks of peripheral tissues, on the other hand, can take their cues from other inputs, such as food consumption.

Presenting food at times when the genome is hunkered down for fasting and energy storage might lead to weight gain and metabolic disorders. Lazar says the experiment has yet to be done to connect the dots between inappropriate food timing, epigenetic activity dysregulated by the clock, and metabolic diseases. But humans, particularly those in developed countries with abundant artificial light, late-night TV, and 24-hour diners, have been putting themselves through an inadvertent experiment over the last few decades. No longer does daylight dictate the times when we eat. "That is the cycle that has gone wrong in the last 50 years," says Panda.

With caution and caveats, one could speculate that this is, in part, why obesity and metabolic disorders have escalated to epidemic levels, particularly when mistimed eating is coupled with a high-fat, high-carbohydrate diet. It stands to reason that our metabolic functions, as controlled by the circadian clock, evolved to cycle in harmony with the Earth's daily rhythms, to optimize processes such as energy use and storage. In doing so, we became adapted to eat during the daytime, and maladapted for eating at night. Opposing these rhythms, as many of us now do, may challenge our bodies' normal cycles and set us up for disease. "Like many evolutionary arguments, it's hard to prove," says Lazar. "But otherwise it's hard to imagine why else we would need things so tightly linked to the Earth's rotation." 


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