Circadian Clock Influences Diabetes and Obesity

Three recent publications are shedding light on how the circadian clock can influence the development of diabetes and obesity. A circadian clock is a biochemical mechanism that fluctuates within a period of 24 hours, coordinated with the day-night cycle. Studies in both mice and men have found a link between the operation of the biological clock and various aspects of metabolism.

One study found severe metabolic consequences in mice exposed to constant light, which disturbed the normal internal clock. Claudia Coomans and colleagues published their study in The FASEB Journal. They subjected male mice to constant light to examine the effects of the disturbed circadian rhythm on energy metabolism and insulin sensitivity. The researchers observed a gradual degradation of their bodies’ internal clocks until its function reached a level that normally occurs in old mice. Ultimately the mice lost their 24-hour rhythm in energy metabolism and insulin sensitivity.

Food intake was increased (+26%), energy expenditure decreased (−13%), and the researchers observed body weight gain after 4 weeks of constant light exposure. Interestingly, the weight gain developed more rapidly in response to the constant light exposure than to a high fat diet.

Coomans’ research is similar to a study in Current Biology that showed that disruption of the circadian clock increases the risk of obesity, diabetes, and heart disease. This mouse study conducted by a team of Vanderbilt scientists demonstrated that insulin activity is controlled by the circadian clock. Their findings help explain why it is that when you eat can matter as much as what you eat.

A third recent publication about the effects on health of altering normal circadian rhythms comes from a 2012 BioEssays paper by Cathy Wyse. She focused on how the internal human clock struggles to stay in tune with the irregular meal, sleep, and work schedules of the developed world. She examined how this disruption might influence health and cause obesity. Wyse believes that circadian disruption affects human health through systems in the brain that regulate metabolism, leading to an increased likelihood of developing obesity and diabetes.

According to Wyse, “The reason for the relatively sudden increase in global obesity in the developed world seems to be more complicated than simply just diet and physical activity.” Imagine that.

Click here to read more about the Coomans study in Medicalxpress, click here to access the study in The FASEB Journal, click here to read more about the Vanderbilt study in Medicalxpress, click here to access the study in Current Biology, click here to read more about Wyse paper, and click here to access the paper in BioEssays.

A riot of rhythms: neuronal and glial circadian oscillators in the mediobasal hypothalamus. Image © Guilding et al / WikiMedia.

Subscribe by email to follow the accumulating evidence and observations that shape our view of health, obesity, and policy.