According to the CDC, the incidence of obesity in the US is 41.9%, making it a prevalent, dangerous, and expensive disease.
37.3 million Americans, or 11.3% of the US population, have diabetes, according to the CDC. An additional 96 million Americans, or 38.0% of the adult population in the US, have prediabetes.
Researchers at Northwestern Medicine have identified the mechanism by which eating after midnight is associated with weight gain and diabetes.
Although the relationship between eating times, sleep, and obesity is well established, it is still not fully understood. Research has shown that excessive calorie intake can alter fat tissue and interfere with circadian rhythms.
The chemical mechanism by which our internal clocks regulate energy balance may for the first time constitute energy release, according to recent Northwestern study. Based on this knowledge, the researcher discovered that heat is best dissipated during the day in the light environment created by the Earth’s rotation. These findings have significant ramifications for everything from dieting to sleep deprivation as well as how we feed people who need long-term nutritional support.
The paper, “Time-restricted feeding mitigates obesity through adipocyte thermogenesis,” was published on October 20 in Science.
“It is well known, albeit poorly understood, that insults to the body clock are going to be insults to metabolism,” said corresponding study author Dr. Joseph T. Bass, the Charles F. Kettering Professor of Medicine at Northwestern University Feinberg School of Medicine. He also is a Northwestern Medicine endocrinologist. “When animals consume Western-style cafeteria diets — high fat, high carb — the clock gets scrambled,” Bass said. “The clock is sensitive to the time people eat, especially in fat tissue, and that sensitivity is thrown off by high-fat diets. We still don’t understand why that is, but what we do know is that as animals become obese, they start to eat more when they should be asleep. This research shows why that matters.”
In the experiment, nocturnal mice were only given a high-fat diet during their inactive (during the day) or active (during the night) periods. Mice fed during the daytime gained more weight than those fed during the night within a week. The scientists fixed the temperature at 30 degrees, where mice use the least energy, to lessen the impact of temperature on their findings.
“We thought maybe there’s a component of energy balance where mice are expending more energy eating at specific times,” Hepler said. “That’s why they can eat the same amount of food at different times of the day and be healthier when they eat during active periods versus when they should be sleeping.”
The team investigated the metabolism of adipose tissue to see if the increased energy expenditure had any impact on the endocrine system. Investigators discovered that it did, and that mice with genetically enhanced thermogenesis—or heat release from adipose cells—were less likely to acquire weight and had better health. Additionally, Hepler found unsuccessful creatine cycling in fat tissues, which suggests that creatine may be the mechanism underpinning heat release. This process involves the storage and release of chemical energy from creatine, a substance that aids in energy maintenance.
The science is supported by studies conducted more than 20 years ago at Northwestern University by Bass and colleagues, who discovered a connection between animal body weight, obesity, and metabolism and the internal molecular clock. Figuring out what it all means and identifying the regulatory mechanisms that cause the association has been difficult for Bass’s team, which focuses on employing genetic techniques to research physiology. They are closer now thanks to this study.
According to Bass, the results may influence chronic treatment, particularly when patients are using stomach feeding tubes. Patients are frequently fed when they sleep at night because this is when they are expending the least amount of energy. These patients had higher than average rates of diabetes and obesity, which Bass believes may be the cause of
Hepler will continue to research creatine metabolism. “We need to figure out how, mechanistically, the circadian clock controls creatine metabolism so that we can figure out how to boost it,” she said. “Clocks are doing much to metabolic health at the level of fat tissue, and we don’t know how much yet.”
Parvathy Sukumaran 
