I’ve heard many conflicting opinions about which part of the day (morning, afternoon, or night) I should workout to help achieve my fitness goals. I’ve been told that exercising in the morning is the best time because you kick-start your metabolism and burn calories throughout the rest of the day. Conversely, I’ve been told that working out at night helps you fall and stay asleep, because your body is fatigued and more restful after a workout. This clashing of opinions reminds me of a similar debate of whether you should put ice or heat on a sore muscle. Both are beneficial, but is one more beneficial than the other? Is a specific time of day more influential in the process of weight loss?
An experimental study was conducted on 29 overweight and inactive post-menopausal women that studied if morning or night walks led to the most weight loss. This study was not a blind procedure, as the women are clearly able to tell whether it is daytime or nighttime. The results show that the group of 15 that went for nightly walks lost more weight than the group that exercised in the morning. The scientists found a link between nighttime walks and dietary changes. It seemed that the women exercising at night would consume more at breakfast time than those 14 women that exercised in the morning. This link could help to explain the weight loss seen in the nighttime group. Eating a heavier breakfast could have possibly suppressed their hunger, causing them to not overeat throughout the day. There could also be other confounding variables at play here such as intensity of the walks, metabolic rate of the participant, what specifically the women were eating, etc. Although the study’s results did prove that evening exercises yield the most weight loss, the demographic being studied is not broad enough to apply to most college students, in fact, it eliminates all males because it follows post-menstrual women. It seems that the study was done well but it was a very small sample size (29 women). Because of these factors, I wouldn’t necessarily change my workout time from morning to night.
Another experimental study conducted in 2010 followed men ages 18-25 (all considered to be “healthy”, the qualifications were not specified). The aim of the study was to figure out if eating breakfast or fasting leads to more weight loss. This study occurred over a span of six weeks. The control group did not exercise while the experimental group was taking was in high-endurance workouts. Within the experimental group, several participants ate carbohydrates before working out, while the others did not eat anything (fasted) before their training session. The results found concluded (for the first time) that not eating breakfast and working out led to more weight loss in their test subjects. Although this study does not test for nighttime workout benefits, it does show that there is a strong relationship between morning workouts and weight loss. But the study does say that it is the first time these results have been proven, and the number of subjects is unspecified. So before anyone makes changes to your diet or exercise routines, you should wait to see if there are any other follow up studies that agree or refute the results of this particular experiment.
All in all, it seems that the verdict of this question is inconclusive. The results from these two studies contradict one another, however there seems to be an overlap of some sort. Each study placed their participants on regimented workout routines. Everyone in the experimental groups in the two studies did lose weight. It just so happens that the women working out at night, and the men who fasted before working out, lost more weight than the others in the study. It’s possible that the time of day isn’t as crucial to losing weight, as is the consistency of diet and regularity of getting to the gym.