Morning Workouts Linked to Lower Obesity Risk, Study Finds

A recent study has found a significant correlation between the timing of workouts and weight management. Adults who engage in moderate-to-vigorous exercise early in the morning appear to have a lower risk of being overweight or obese compared to those who exercise later in the day.

The research, led by Tongyu Ma, an assistant professor of exercise physiology at Franklin Pierce University, highlights that individuals who maintain a morning workout routine have a body mass index (BMI) that’s 2 units lower and a waist circumference 1.5 inches shorter than those who exercise at other times. Both BMI and waist circumference are critical indicators of obesity risk.

To delve into this relationship, the study assessed the obesity status of nearly 5,300 adult men and women who were part of the U.S. National Health and Nutrition Examination Survey conducted between 2003 and 2006. Participants were required to wear a hip accelerometer for four to seven consecutive days, providing insights into their activity levels. Based on their exercise patterns, they were categorized into morning, midday, or evening exercise groups.

The findings revealed a compelling connection: those exercising between 7 a.m. and 9 a.m. were associated with a lower risk of being overweight or obese. While all participants were categorized as overweight (with BMI values between 25 and 29.9), the morning exercisers had an average BMI of 25.9. In comparison, the midday and evening exercise groups had average BMI scores of 27.6 and 27.2, respectively.

Waist circumference measurements further supported this trend. Morning exercisers had an average measurement of about 36 inches, whereas midday and evening exercisers were between 37 and 38 inches.

However, Ma emphasized that this study only showcases an association, not a definitive cause and effect. In a surprising turn, the research also found that morning exercisers spent the most time being sedentary. Ma suggests that these individuals might be engaging in a more intense morning workout session than their counterparts who exercise later in the day.

It was also noted that morning exercisers consumed fewer calories and had healthier eating habits compared to those in the midday and evening groups. Ma posited a potential explanation: early in the morning, our bodies are in a low-energy state due to overnight fasting. With limited carbohydrates available, the body might rely more on fat reserves for energy, making morning workouts potentially more effective for weight management.

In summary, while more research is needed to determine a direct cause and effect, this study suggests that the early bird not only catches the worm but might also have an edge in maintaining a healthier weight.


The diurnal pattern of moderate-to-vigorous physical activity and obesity: a cross-sectional analysis

Tongyu Ma,  Thomas Bennett,  Chong-Do Lee,  Mairead Wicklow