Firefighters working 24-hour shifts who only ate between 9am and 7pm saw improvements in heart health, blood sugar and blood pressure
Firefighters and other shift workers could benefit from time-restricted eating
Angie Sharp / Alamy Stock
Eating within the same 10-hour time frame daily may counter the health consequences of shift work, such as an increased risk of diabetes, cardiovascular disease and cancer.
Shift work disrupts circadian rhythms, the 24-hour cycles of sleep and wake that also govern the activity of various organs. Eating can regulate these rhythms. To see whether changing what and when people eat could counteract the harms of shift work, Satchidananda Panda at the Salk Institute for Biological Studies in California and his colleagues studied firefighters working 24-hour shifts.
They advised 137 firefighters in San Diego, California, to spend 12 weeks following the Mediterranean diet – high in fruits, vegetables, legumes, whole grains and olive oil, and low in red meat and sugar. They asked 70 to eat in the same 10-hour time frame each day and the other 67 to eat whenever they liked. Before the study, the groups had no significant health differences, and more than 70 per cent of participants had at least one risk factor for heart or metabolic diseases such as high blood pressure or obesity.
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Participants recorded when they ate using a smartphone app and answered surveys on sleep and well-being before and after the study. Researchers also collected blood samples and tracked participants’ weight. Firefighters in the time-restricted eating group saw greater improvements in health after 12 weeks compared with the control group. The biggest improvement was in the size of harmful cholesterol particles known as very-low density lipoproteins, which increase the risk of cardiovascular disease. On average, the size of these particles decreased by nearly 3 per cent in the time-restricted eating group compared with a 0.5 per cent decrease in the control group.
“This is very important because a leading cause of death or disability for firefighters is cardiovascular disease,” says Panda.
Firefighters on a time-restricted diet also had, on average, slightly greater reductions in weight, diastolic blood pressure, alcohol consumption, caloric intake and sleep disturbances. The time-restricted diet also led to greater declines in blood pressure and blood sugar among firefighters with elevated levels of these markers to begin with.
“If firefighters eat a Mediterranean diet, that’s good, but if they combine the diet with time-restricted eating, that’s even better,” says Panda. Eating helps dictate when organs perform certain functions. The stomach, for example, usually digests food during the day and repairs itself at night but can’t perform these functions simultaneously. A consistent daytime eating schedule, reinforces this pattern, and ensures various organs have time to repair themselves, he says.
A time-restricted diet could also help prevent health problems related to shift work, as previous research has shown it reduces rates of conditions such as diabetes in mice who had disrupted circadian rhythms and an increased risk of obesity and diabetes.
However, it isn’t clear from the current study whether the diet is feasible in the long term, says Jingyi Qian at Harvard University in Massachusetts. “If we want to have consistent benefits for shift workers, we need to know whether they can adhere to this intervention for a year or even longer,” she says.
Journal reference: Cell Metabolism, DOI: 10.1016/j.cmet.2022.08.018
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