The “95%” statistic for failed diets is commonplace in blogs and publications of health and wellness, and while a google search will also reveal a large amount of scrutiny regarding this dark portent of inevitable failure, weight-regain is still an enormous problem facing a country where, according to the CDC, obesity affects 93.3 million Americans. 

A 2007 study reported that of people who made efforts to lose at least 10% or more of their body weight, one third of them regained it the following year. Ominously, weight-loss maintenance can be as little as 3.2% depending on who a given study or meta-analysis includes.

A strategy as old as life itself

There are plenty of dietary, fitness, and lifestyle strategies available for an individual wanting to lose weight or reduce their risk for cardiovascular disease. One such theater is circadian biology, an emerging area of study investigating the body’s relationship to the 24 hour day-night cycle of our planet. Here, many researchers believe they’re coming up with a better solution to combat obesity and heart disease; but how exactly do circadian rhythms affect human life, and what can we learn from them to help keep the weight off?

Circadian rhythms can be observed in almost every living thing, including animals, plants, and fungi. It is a blanket term to describe biological functions dependent on the 24 hour rotation of our planet. Through photoreceptors in our eyes, a part of the brain called the Suprachiasmatic-nucleus works as a master cellular oscillator, or “clock,” activating hundreds of genetic pathways involved in things like metabolism and immune-response based on the perception of light, or lack of light, in the environment.

Out of this field, a question arises regarding weight-loss, weight-management, and disease prevention: what if what you eat matters less than when you eat? Fasting for instance is another term dripping from the lips of bloggers and scientists alike, as the benefits of fasting are wide and diverse. But if an individual can’t manage their sugar intake or find 30 minutes in a day for exercise, one could imagine asking them to skip breakfast, lunch, and dinner for two days would only result in failure.

The panda and the mouse

However, in 2018 Dr. Satchin Panda showed that when a group of mice which could only access their high-sugar high-fat chow, meant to induce obesity, during a 10-hour window of their active period of the day, they were protected from weight-gain and other metabolic diseases while also displaying much better markers of metabolic health such as blood-glucose, blood-lipids, circulating cholesterol, and insulin sensitivity. Another control group of mice had access to food whenever they wanted, and these gained significant weight and almost all developed some kind of metabolic disorder, i.e. cardiovascular disease, obesity, etc. 

This strategy, called Time-restricted feeding, shows great promise in early trials with humans, and fits in perfectly with existing circadian literature. Many genes that regulate metabolism or hormonal production exist in a relationship with biological functions meant to track daylight, time, and darkness. One major breakthrough in this field came from a discovery which found that increased melatonin signaling prevented the secretion of insulin in the blood. Insulin turns excess carbs and sugar into an energy storage form called glycogen; an important process in maintaining metabolic health.

 In 2009 Genome-wide association studies found that melatonin receptor 1 B was among the most common genetic variants associated with type-2 diabetes. Melatonin, AKA the Sleep Hormone, AKA the Hormone of Darkness, is produced in the pineal gland of the brain when the circadian clocks in the body enter the nocturnal phase of the day. Melatonin is an effective promoter of sleep, while also fulfilling a number of other functions. 

This is damning science for those among us who enjoy a late-night glass of wine, or midnight snack, as our bodies are not able to appropriately metabolize the carbs and fats eaten after the sun goes down and melatonin is flowing. In fact, a study of 26,000 men with a 16 year follow up found that late-night caloric consumption led to a 55% increase in the risk for cardiovascular disease.

A gateway strategy

Circadian biology would suggest there are not just unhealthy foods but unhealthy times to eat, and that ice cream for breakfast may be better in the long term than after dinner. A variety of different research including epidemiology studies and other smaller-case studies has shown that if you can consume all of your meals within an 8 to 10 hour window, the risk for cardiovascular and metabolic diseases could very well go down.

If super-leniency is required, even a 12 hour window is enough to see similar benefit to those experienced by the mice in Dr. Panda’s lab. However an 8 hour window is more ideal not just for metabolism, but also because 16 hours without food allows for autophagy, the master cellular cleanup and repair process, to carry on its absolutely vital processes far longer. 

It would be immoral to suggest that TRE is a magical cure for obesity and diabetes; the average person would still be far better off if they could remove junk food from their diet entirely, along with the undeniable fact that there has never been a single eating strategy that works for everyone. But in TRE there exists an easy-to-implement and often more desirable strategy for people who may be at risk of obesity and type-2 diabetes.