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It seems like every day we hear new, often conflicting advice regarding the merits of dieting, not dieting, eating more carbs, less carbs, reducing sugar, exercising more, and various ways to maintain healthy weight. But a growing body of evidence points in a different direction. While we tend to focus on the type of food we eat, new research suggests that our bodies may react just as much to when we eat it.

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Studies of shift workers provided some of the first hints in this direction. Reviewing studies of shift workers, researchers in the Netherlands found suggestions that shift workers tended to gain more weight over time than people with more regular schedules. The researchers felt that more information was necessary to conclusively prove a link, but they did suggest a mechanism: differential day/night metabolism of glucose. Mammals metabolize glucose more effectively during the day, when we normally eat. When humans eat more at night, they metabolize less glucose, which ends up being stored as fat.

But the full explanation for a connection between meal timing and weight may go deeper. We may simply not be evolved for modern life. For most mammals, food does not come regularly. Carnivores, for example, may go days between meals. The three meals a day (plus snacks) that humans in developing countries typically eat do not conform to this pattern. Furthermore, access to light outside of natural daylight allows us to stay up (and eat) later than ever before, running into the glucose metabolism problem.

This suggests that we are evolved to eat at far more intermittent intervals. Shifting meals to allow bigger gaps between meals, either by eating on alternate days or even just skipping a few meals a week, may be better suited to our evolutionary biology. There is evidence that such an eating schedule has health benefits beyond just weight management. Cardiovascular health, age-related decline, and inflammatory disease may all be improved by an altered meal schedule.

Given our modern lifestyle, these restrictions might be difficult for many people to follow. Most people with the option prefer to eat every day. If your schedule allows it, the easiest step to take is probably to try to limit nighttime meals. But the most significant result of the new research could be its potential to help move us away from moralizing the connections between eating and health.


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Scandinavian Journal of Work, Environment & Health, Vol. 37, No. 4 (July 2011),pp. 263-275
the Scandinavian Journal of Work, Environment & Health, the Finnish Institute of Occupational Health, the Danish National Research Centre for the Working Environment, and the Norwegian National Institute of Occupational Health
Proceedings of the National Academy of Sciences of the United States, Vol. 111, No. 47 (November 25, 2014), pp. 16647-16653
National Academy of Sciences