Off kilter: Can a diet rich in saturated fats mess up our daily cycles?
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CHICAGO: A high-fat diet is not just bad for your heart, it can also throw off your body clock, setting off a chain reaction that interferes with many metabolic functions, says a new study.
The study of mice suggests that the functioning of the body's circadian rhythm – the internal 24-hour clock, which regulates our sleep/wake cycle and the timing of hunger pangs – is closely tied to the rhythms of certain metabolic processes.
Vicious circle
A modern, 'Western-style' diet with a lot of calories from saturated fat can disrupt the body's clock or circadian rhythms, setting up a vicious circle which throws off the timing of certain metabolic processes, potentially increasing the risk of obesity and diabetes.
"Timing and metabolism evolved together and are almost a conjoined system," said Joe Bass, lead author on the paper and an endocrinologist at Northwestern University in Chicago, USA. "If we perturb the delicate balance between the two, we see deleterious effects," he said in the study published in the journal Cell Metabolism.
He took two groups of mice and put one on a regular diet and the other on a high-fat, high-calorie diet for six weeks.
After two weeks, the mice on a Western-style diet – with 45 per cent of their calories in the form of fat – showed a spontaneous shift in their normal pattern of activity/eating and rest/sleep rhythms. They began to eat during their typical rest or sleep period. The mice on regular diet did not show this behaviour.
Delicate mechanism
"It's not just that the animals are eating more at regular meals," said Bass. "What's happened is that they actually shift their eating habits so that all excess food intake occurs during their normal rest period."
In addition to the behavioural changes, lab tests showed that levels of certain messenger molecules produced by genes that regulate circadian rhythms were depressed in the brain, liver and fat tissues of the mice on the Western-style diet.
"One of the damaging effects of excess calories is to perturb this very delicate and important timing mechanism that is present in all of us," said Bass, noting that the internal 24-hour clock is a feature common to plants, animals and humans. "In so doing, it may exacerbate the process that connects diet to diabetes and obesity."
