Owls have a higher risk of metabolic disorders

Scientists have studied the relationship of chronotype with nutrition, body composition and metabolic markers in healthy women aged 18 to 45 years from Auckland (New Zealand). The Munich Chronotype Questionnaire (MCTQ) was used to determine the chronotype. Based on their sleep-wake patterns, the participants were divided into “larks,” “owls,” and an intermediate group (for example, women who typically went to bed at 11 p.m. and got up at 8 a.m. were placed in the intermediate group).

The participants’ diets were recorded over a period of five non-consecutive days (three weekdays and two weekends), and then the dieticians further refined the portion sizes through in-person interviews to improve the accuracy of the data. Instead of relying only on BMI, the researchers used DXA scanning (dual-energy X-ray absorptiometry). This method allows for accurate measurement of body fat, its distribution (including the ratio of abdominal and hip fat), and the separation of fat mass from muscle mass. Additionally, the women had their blood samples collected to assess biomarkers such as glucose, cholesterol, triglycerides, and hormones related to fat metabolism and appetite regulation (leptin and ghrelin).

The results showed that “owls” had less favorable indicators in almost all parameters compared to “larks” and women of the intermediate type. Although the total number of calories and macronutrients was approximately the same in all groups, the “owls” had a less nutritious diet, and it was found that they consumed less fiber, vitamins, and minerals. Moreover, a significant portion of calories was consumed in the late evening, and such women ate very little in the morning.

The body composition of “owls” was also less favorable. They had a higher BMI, more total body fat, and a higher ratio of abdominal fat to thigh fat, which is considered a marker of increased risk of cardiovascular and metabolic diseases.

Blood tests showed that “owls” had higher levels of insulin and triglycerides and lower levels of “good” cholesterol (HDL). In addition, they had higher levels of leptin (a hormone associated with fat stores) and lower levels of ghrelin (a hormone that signals hunger) compared to other chronotypes.

It is important to note that the timing of meals can also influence the body’s internal clock, suggesting that a late and irregular meal schedule may further increase metabolic risks in individuals with an evening chronotype.

Further research is needed to fully understand the relationship between sleep patterns and the risk of obesity. However, in the long run, this could help develop personalized nutrition and lifestyle recommendations based on individual daily rhythms.