There is mounting evidence to suggest the body clock plays a bigger role in weight management than previously thought. WH chews over the science
There was a time when advice on living your life according to an all-powerful body clock was filed away in the column marked ‘crap people say’, alongside ‘tomatoes prevent sunburn’ and ‘don’t swim after eating’. But researchers are currently engaged in a task best described as a clock-watching.
In recent years, interest in circadian rhythms – the natural biological changes that happen throughout each 24-hour sleep-wake cycle – has risen faster than gym membership in January, making the topic among the buzziest in the wellness world. You could fill a library with the research on the myriad ways in which these cycles influence everything from fertility to mental health. The latest topic in which time is of the essence? Fat.
Last year, two studies led by researchers at Weill Cornell Medicine in New York showed that throwing off the body’s natural clock triggered the growth of fat cells, which, in turn, led to weight gain. Such studies are adding credibility to a way of eating that’s been dubbed the circadian rhythm diet. It promises to optimise how your body metabolises food according to your natural biological clock by restricting consumption to a window of eight to 12 hours – intermittent fasting, essentially. At a time of year when you’re more likely to be seeking evidence-based strategies for sustainable, healthy weight loss, it raises a question: when it comes to dieting, is when more important than what?
Back to the science – the two most recent studies show a critical link between a disrupted circadian rhythm (read: a sleep pattern more unreliable than your flakiest friend) and your chances of gaining weight; this link is a new discovery, says Mary Teruel, associate professor of biochemistry at Weill Cornell Medicine and one of the papers’ senior authors.
Padded cell
The first study found that giving extra glucocorticoid stress hormones to mice (to mimic what happens when circadian rhythms are disrupted) triggered a boost in fat cell growth so significant that the mice more than doubled their fat mass within three weeks.
The second study offered insight into the relationship between these two bodily mechanisms. By attaching two fluorescent markers to different proteins in the mice – including PPARG, a protein that regulates fat cell production – the researchers found that the body’s decision to switch cells into ‘fat cells’ happens within a four-hour window during the night; this offers an explanation as to why late and nocturnal eating can lead to weight gain. ‘Our research shows that stress alone, such as jet-lag or irregular sleep and eating schedules that flatten circadian glucocorticoid rhy
