If your main goal of exercise is weight loss, you may want to consider what time of day you exercise. A new study offers clues that may help you lose weight.

According to a study published in the journal Obesity , exercising between 7 a.m. and 9 a.m. was associated with a lower waist circumference and body mass index (BMI) than people who exercised during the afternoon or evening (BMI). body mass is a value calculated from a person's weight and height)

Those who exercised in the morning had an average BMI of 27.5, compared to those who exercised in the afternoon (9:00am to 4:00pm) and evening (5:00pm to 8:00pm), who had an average BMI of 28.3 .

The reasons why morning exercise may be more effective in weight loss may have to do with both physiology and lifestyle, the study's authors told CNN. Moreover, morning people may be biologically different from "night owls".