A prospective study of weight gain associated with chronotype among college freshmen.

A prospective study of chronotype as a predictor of increased weight gain and body mass index (BMI) among college freshman was undertaken. At baseline, 137 college freshmen were characterized as morning, neutral, or evening types using the reduced version of the Morningness-Eveningness Questionnaire. Additionally, information was collected regarding weight, BMI, and health habits (e.g., junk food and alcohol consumption). These additional measures consisted of a descriptive questionnaire, the Pittsburgh Sleep Quality Index, the International Physical Activity Questionnaire, the Gray-Donald Eating Patterns Questionnaire, and the Positive and Negative Affect Scale. Participants included 79 females and 80 males with a mean age of 18.25 (SD = 0.56) yrs. Eight weeks later, participants returned (N = 54) to complete follow-up measures, which were identical to baseline assessments with the exception of the descriptive questionnaire, in which demographic questions were removed. Evening types had a significantly greater BMI gain (p < 0.05) when compared with morning/neutral types. Health behaviors did not differ by chronotype. Future studies should seek to clarify the mechanisms underlying the chronotype-BMI/weight gain relationship.