Breakfast and Body-Mass Index

Are you a morning person or an evening person? According to a recent study in the journal Diabetic Medicine, it might make a difference to your BMI — body-mass index, that is (a standard way of assessing obesity that measures weight relative to height). According to Sirimon Reutrakul, MD, lead author of the study, “Later breakfast time is a novel risk factor associated with a higher BMI among people with Type 2 diabetes.”


For the study, the researchers enlisted 210 workers in Thailand who had Type 2 diabetes. They used a questionnaire to inquire about such things as when the workers preferred to wake up and go to bed, when they engaged in mental activity such as work or reading, and what time of day they exercised. The researchers also collected data on what time the subjects ate meals and how many calories they consumed daily, as well as how much they weighed and what their BMIs were. Sleep duration and quality were also measured. The researchers classified 113 of the study participants as having a morning preference and 97 as having an evening preference.

The researchers found that an evening preference was associated with a higher BMI. Also, and most notably, an earlier breakfast was associated with a lower BMI. Lunch and dinner times, however, as well as caloric intake, were not associated with a higher BMI. The key factor, then, appeared to be breakfast time. Dr. Reutrakul theorized that eating breakfast later might somehow misalign the internal biological clock and this in some way leads to a dysfunction in energy metabolism. Further research might shed light on this possibility. As Dr. Reutrakul explained, “It remains to be investigated if eating breakfast earlier will help with body weight.”

Want to learn more about the relationship between breakfast and diabetes? Read “Dealing With After-Meal Blood Sugar Spikes? Don’t Skip Breakfast,” “The Benefits of Breakfast,” and “The Importance of Breakfast for Diabetes.”

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