Circadian rhythms are essentially about how our body clock works to you and me. Recent evidence from a study by the National Institute for Health and Welfare at the Dept. of Public Health Solutions in Helsinki, Finland, suggests our internal body clock affects what we eat and indeed our general health. It poses some interesting questions for those of us who think we are a morning person as opposed to any other time. It seems morning people may make better healthy food choices as a consequence of how our circadian rhythms are operating.

The research examined data from 2,000 people chosen at random using data from the national FUNRISK study started in 2007. They established what their body clock or circadian rhythms, technically known as their chronotype and looked at their food choices and when they ate. The study showed significant differences between the two basic chronotypes in terms of how much food and energy was consumed.

Evening types seem to be performing the less well in terms of food choice than their morning counterparts. The morning types eat generally more protein and less sugar such as sucrose in the morning. When it comes to the evening, the morning types still eat healthily by eating less sugar as sucrose, fats and saturated fatty acids. Perhaps most striking was what happened at the weekends. These differences in eating habits were even more pronounced because the morning types had “better” and more regular feeding habits and they ate more often, in fact possibly twice as often. Evening people don’t seem to sleep as well or are not as active physically. There was no reference to their mental health.

The evidence comes on the back of previous assessments about evening types who seem to engage with less nutritious food. In other words, they consume more ‘junk’ food including larger amounts of soft drinks, higher intakes of various fats but less vegetables and fibre. The overall quality of the diet is said to be much lower for evening types compared to morning types (Baron et al., 2011; Kanerva et al., 2012; Maukonen et al., 2016)

The researchers almost paraphrased Benjamin Franklin’s famous saying “early to bed, early to rise, makes a man healthy, wealthy and wise”. The implications for evening people is that their feeding habits make them more prone to obesity, diabetes and a host of other unwelcome conditions. Likewise, it may explain why diets are difficult to sustain for some compared to others because their body clocks are almost dictating when and what they need to eat.

The evidence is provided in greater detail by The Obesity Society which has offered a press release for editing or publication in full.

Maukonen, M., Kanerva, N., Partonen, T., Kronholm, E., Tapanainen, H., Kontto, J. and Männistö, S. (2017), Chronotype differences in timing of energy and macronutrient intakes: A population-based study in adults. Obesity, 25: 608–615. doi:10.1002/oby.21747

References:

Baron, K.G., Reid, K.J., Kern, A.S., Zee, P.C. (2011) Role of sleep timing in caloric intake and BMI. Obesity (Silver Spring). 19 pp. 1374-1381.

Kanerva, N., Kronholm, E., Partonen, T., et al. (20120) Tendency toward eveningness is associated with unhealthy dietary habits. Chronobiol. Int. 29 pp. 920-927

Maukonen, M., Kanerva, N., Partonen, T., et al. (2016) The associations between chronotype, a healthy diet and obesity. Chronobiol. Int. 33 pp. 972-981.