Will Shift Work Make You Fat? Check Your ‘Lipid Rhythm’

Scientists have found that our body clock controls the amount of lipids present in our bloodstream at different times of the day, giving rise to widespread differences in lipid rhythm between individuals.

Asian Scientist (Aug. 15, 2013) – Scientists have discovered that our body clock controls the amount of lipids (fat-storing molecules) present in our bloodstream at different times of the day, giving rise to widespread differences in ‘lipid rhythm’ between individuals.

The study, published in the Proceedings of the National Academy of Sciences, provides a new explanation for why some people gain weight when doing shift work.

The researchers, led by Dr Joshua Gooley at the Duke-NUS Graduate Medical School in Singapore, tracked the amounts of 263 lipids in the bloodstreams of 20 healthy volunteers over a period of 28 hours.

Through analysis of the lipid data, they found that most lipids fluctuated in a rhythmic manner, evidence that they were controlled by the body’s circadian clock, which generates 24-hour rhythms like the sleep cycle.

However, there were widespread differences in the specific lipids that were subjected to circadian clock control in different individuals. Differences were also found in the timing and strength of the rhythm as some individuals exhibited peak lipid levels in the morning while others had evening peaks.

This prompted the researchers to propose that people may fall into two different lipid rhythm types: “morning-type” and “evening-type” individuals who have their lipid levels peaking in the morning and evening, respectively.

“Previously, the descriptions ‘early bird’ or ‘night owl’ have been used for people who prefer to wake up early or go to bed late. Our study shows that there are morning and evening types based on variation in levels of glucose (sugar) and lipids in their blood, and this may explain why some people are better suited to shift work than others,” said Dr Gooley.

According to the researchers, the results of this study may also help identify people who are at greater risk of developing metabolic disorders such as diabetes. This is because such disorders have been linked to disruption of the circadian clock. An example of circadian clock disruption is when people do shift work that require them to have irregular sleep schedules.

The body’s ability to break down fat is also impaired at night, when we would normally be sleeping and fasting. For individuals whose lipid levels rise across the night, consuming meals at night could lead to even higher levels of fat in the bloodstream.

Therefore, further research looking at how individual differences in metabolism contribute to disease risk could lead to better treatment of such diseases.

The article can be found at: Chua et al. (2013) Extensive Diversity In Circadian Regulation Of Plasma Lipids And Evidence For Different Circadian Metabolic Phenotypes In Humans.


Source: Duke-NUS; Photo: idealisms/Flickr/CC.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.

Yew Chung is a postdoctoral research fellow at the Duke-NUS Graduate Medical School, Singapore.

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