New Research Reveals the Best Time of Day to Work Out for Weight Loss

Exercising in the morning may help better manage weight, a new study finds.

Embracing physical activity, like light-to-moderate exercise, can have great benefits for your health. While this is true no matter what time of day it is, new research suggests that a certain workout schedule may best suit those focused on managing their weight.

The new study, published earlier this month in Obesity, found that people who exercise between 7 A.M. and 9 A.M. were able to better manage and keep weight off than those whose workout regimen took place in the afternoons or evenings.

In order to find this, the research team analyzed data from 5,285 people who participated in the Centers for Disease Control and Prevention’s (CDC) 2003 to 2006 National Health and Nutrition Examination Survey (NHANES).

Participants were grouped based on physical activity habits: morning, midday, and evening. Each participant wore an accelerometer on their right hip during their waking hours to measure physical activity for four consecutive days up to seven days, after their initial examinations.

The researchers found that body mass index (BMI) measurements and waist sizes were lower for those in those morning hours than later in the day, indicating lower obesity risks than people who opted to exercise in the afternoons or evenings.

While there are other factors to take into account when discussing obesity (like diet and genetics), these findings can be useful for people looking to get the most out of their daily workout.

Diana Thiara, MD, the medical director at UCSF Weight Management Clinic and an assistant clinical professor of medicine in the Division of General Internal Medicine at UCSF, emphasized that it’s important to put this study in context, explaining that “it’s hard to extrapolate too much from the results.”

Here’s how morning exercise may better help people manage weight, and additional recommendations for sustainable, healthy workout habits.

Getty Images / BartekSzewczyk

A possible explanation for the study’s findings might be that fasting overnight while sleeping reduces glucose levels, which results in the body turning to fat oxidation for energy use during optimal morning workout times, explained Tongyu Ma, MBBS, PhD, corresponding author and research assistant professor at the Hong Kong Polytechnic University and Franklin Pierce University.

But, there are elements of the study that leave out certain considerations.

“This is a retrospective cross-sectional study which tells more about an observation,” Thiara said. “If we want to understand if there is a cause-and-effect relationship between an intervention and an outcome, we would want to see a randomized control trial.”

She also pointed out that over 75% of the study participants were White, so it’s not a diverse or representative study population.

And, there was a lack of control regarding how many calories each participant consumed throughout the day—this is hugely meaningful in research regarding BMI, Thiara explained.

Thiara echoed Ma in saying that, in theory, it could be beneficial to work out in those morning hours before you break your overnight fast. She said this fasted-state exercise can increase fat oxidation. and that other studies suggest that exercising “during a fasted state can decrease the total amount of calories people eat in 24 hours.”

Hence, this could help someone prevent weight gain and prevent weight loss.

“But, to be clear, these things have not been proven in large-scale randomized control trials, so we cannot clearly and definitively say that morning exercise prevents or decreases the risk of obesity,” Thiara stressed.

Thiara and Ma both said consistent exercise at any point in the day is beneficial for your overall health, despite the specific hour it takes place.

“People get in the weeds about how to do things ‘perfectly,’ but the reality is that we should focus on consistently moving our bodies regularly throughout the day and aim to get our heart rates elevated,” Thiara said. “Consistency is key—perfection can be a hindrance.”

Ma notes that the new study “suggests morning is the best time of day,” but that there needs to be more evidence and further research to deepen the understanding of why this might be the case.

Looking ahead, Ma said a clinical trial would give him and his colleagues “more confidence in providing scientific evidence” behind some of the suggestions of this study.

But for now, what’s most important for people who are working to manage their weight to understand, is that any exercise is a positive step forward.

Thiara said it’s important to find time for some kind of physical activity you enjoy and can continue to do, especially if you are looking to keep off weight.

“Exercise is really important for cardiometabolic health—things like cholesterol, blood pressure, and blood sugar—and it’s really important to help with keeping off any weight you’ve lost,” she said.

Thiara recommends people who are beginning to exercise for the first time start with something simple. Something like a 15-to-30-minute walk a few times each week could be an accessible way to start incorporating physical activity into your daily schedule.

“Once you have that routine under your belt, increase the time and think about changing up your activities, like swimming, biking, gardening, hiking, sports, and dance,” she said. “Aim for 150 minutes per week of activity.”

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