Why your body’s internal clock might need a tune-up

Low-fat or high-fat diets, lots of protein, less sugar, more exercise … it seems like we’ve tried everything to tackle the rising rates of diabetes and obesity in our society.

But one factor that may have been overlooked is a very ancient biological process that is a master controller of our well-being: our molecular clock. That’s why a new series of articles in the journal Science rounds up the latest research into our body’s natural rhythms. 

What does a molecular clock have to do with obesity and diabetes?

Our bodies have a roughly 24-hour sleep-wake cycle called the circadian rhythm. If you’ve ever experienced jet lag, you’re intimately familiar with the concept. 

Circadian rhythms are under the control of a molecular clock, one that is active in all the cells of our body and is linked to how we take in and process calories. In other words, our metabolism. This new research is slowly uncovering how our molecular clock and metabolism are closely connected. 

Think about it this way: for literally millions of years, life has experienced either feast or famine. Some early plant life couldn’t make food at night when there was no sun, while hunters who relied on the cover of darkness wouldn’t eat all day. This schedule has been programmed into our cells through millions upon millions of years of evolution.

But in 2016, we have 24/7 convenience stores, late night diners and fridges that can be stockpiled with food. This is not natural.

What is our molecular clock?

It’s this incredible feat of genetics that influences your body in all kinds of ways. In fact, all photosensitive organisms — from tiny microscopic organisms to blind mole rats — have an internal clock that keeps them on a roughly 24-hour daily cycle.

It all starts with a fascinating genetic cascade that revolves around two key proteins called period and cryptochrome.

As you can see in this graphic, our cellular clock is pretty complicated — but our sleep-wake cycle comes down to two proteins called period and cryptochrome. (Northwestern University)

In humans, cryptochrome production begins at nightfall and slowly builds up as the darkness continues. The levels then act as inhibitors of their own production: the higher the levels accumulate, the more they turn themselves off. Period works in the opposite way, starting production at daybreak and levelling off as the day progresses. 

This levelling-off process takes about 12 hours, at which point the proteins take another 12 hours to build again. Thus, our 24-hour cycle. 

How does this alter our understanding of obesity and diabetes?

There have been some really amazing experiments in flies, worms and mice that have helped answer that question and more. One scientist doing amazing work in this area is Dr. Joseph Bass from Northwestern University, who conducted research on mice to see what happens when the molecular clock mechanism is changed. 

He told me the result of one of his experiments was “a propensity towards obesity and also toward diabetes.” 

And there are many other similar experiments that show just how much diet can influence the molecular clock thereby changing the way energy is distributed and used in the body.

Is disruption of the molecular clock making us fat?

Yes and no.

What this research tells us is that the link between metabolism and internal circadian rhythm is stronger than was ever thought before.

Think about it: we barely fast in a day. As a culture, we eat pretty much all day long — with breakfast first thing in the morning and our last sip of wine at the end of the evening.

Our consumption of calories every waking moment is screwing up our biological clock because it doesn’t give it a chance to wind down for the night, limiting the time that our body needs to do housekeeping stuff like repairing tissue.

Our sleep-wake patterns are a product of millions of years of evolution. (Unsplash / Benjamin Combs)

Our bodies naturally wait until periods of fasting (not eating for about four hours) to start to fix general damage that life inflicts on us. If we’re constantly eating, our bodies can’t do that. 

Should we shorten the amount of time in a day we eat?

If research in mice is any indication, we probably should.

Satchin Panda from the Salk Institute for Biological Sciences did an experiment where he separated two genetically identical sets of mice. One set was raised with a fixed number of calories that were available to them any time of the day. The other set was given the exact same number of calories, but their food was given over an eight-hour period — the rest of the time they were left to fast. The results were amazing: 

“The mice that ate whenever they wanted, they were quite obese,” said Panda. “The mice that ate for only eight hours were completely normal.” 

Keep in mind that this has not been done in humans. But it’s becoming clearer and clearer that understanding our circadian rhythm and molecular clock could be a crucial part of caring for our health.