Working out during this 2-hour period of time is ideal for weight loss, study finds

The global rise in obesity, a major risk factor for chronic illnesses and early mortality, has brought attention to the role of physical activity as a key element in managing weight effectively. While physical activity is clearly beneficial for weight management, the question of when to exercise for the best results remains contentious. Some research suggests that morning exercise might be optimal, while other studies highlight the potential benefits of evening workouts.

Emerging evidence shows that timing could play a significant role in optimizing weight management. A cross-sectional analysis of accelerometry data from the Women’s Health Study indicated that a lower percentage of physical activity done in the morning was independently associated with increased obesity risk.

On the other hand, a recent study found evening exercise was more strongly correlated with a lower body mass index (BMI). These contrasting results show that the best time for physical activity is still up for debate.

Underlying this timing dilemma is the science of circadian rhythms, which are natural cycles in the body that regulate many processes, including metabolism, insulin sensitivity, and energy storage. The human body’s physiological and metabolic processes follow these circadian rhythms, which can impact how we metabolize food and store energy throughout the day.

Shift workers, who often have disrupted circadian patterns, are more susceptible to obesity and metabolic issues, suggesting that doing the right thing at the right time is crucial for maintaining a healthy body weight.

In experimental studies, the time of day for physical activity appears to influence energy expenditure and fat oxidation. Research has shown that morning workouts, particularly when done after an overnight fast, tend to promote greater fat oxidation compared to evening workouts.

This is thought to occur due to more significant depletion of liver glycogen after fasted exercise, which in turn triggers lipid mobilization and oxidation. Additionally, exercising in a fasted state has been associated with reduced total energy intake over 24 hours, implying that early morning, fasted-state exercise could be advantageous for weight loss.

However, studies on appetite control following exercise present mixed results. While some research supports the idea that morning exercisers experience a reduction in subsequent energy intake, other studies show no significant differences between morning and evening exercise in terms of post-exercise appetite suppression.

The overnight fast is a key factor that differentiates morning exercise from workouts done later in the day and may contribute to its effectiveness for weight management.

Accelerometers are commonly used to measure physical activity, yet most studies have focused on frequency, intensity, and duration rather than the timing of physical activity throughout the day. The influence of accumulating physical activity at different times on obesity is still largely unexplored.

Moreover, it’s not clear whether adhering to physical activity guidelines—150 minutes per week of moderate-to-vigorous physical activity—at different times of day provides equal benefits in reducing obesity risk.

Dr. Natalie Azar, NBC News medical contributor, summed up the debate by stating, "The best time to exercise is when you can fit it in for sure. If first thing in the morning is your jam, by all means keep on doing it." She emphasized that the specific timing might depend on personal goals.

Recent research suggests that evening workouts might be better for managing obesity and blood sugar levels. But no matter when you exercise, the health benefits are significant, including enhanced cardiovascular health and muscle strength.

Morning exercise is often the easiest time for people to fit fitness into their schedules. Many experts agree that early morning workouts can provide various benefits, especially for weight loss.

A 2023 study published in the journal Obesity analyzed data from over 5,200 participants and found that moderate to vigorous exercise between 7 a.m. and 9 a.m. was linked to a lower BMI compared to exercising at other times of the day.

Morning exercisers tended to have healthier habits overall—they were more likely to avoid tobacco and alcohol, exercise consistently at the same time each day, and consume fewer calories compared to those who exercised later.

Tongyu Ma, the lead researcher of the study from The Hong Kong Polytechnic University, cautiously suggested that exercising early in the morning before eating might lead to more weight loss than workouts at other times.

However, Cameron Mitchell, a kinesiology expert at The University of British Columbia, urged caution, noting that the study's findings did not conclusively determine that morning exercise alone led to "optimal health." It’s possible that the other health-conscious habits practiced by morning exercisers played a significant role in these outcomes.

Morning exercise may also prompt biological benefits linked to circadian rhythms. For example, research suggests that exercising early may help reset the body’s molecular clock, which in turn can boost metabolic health and assist with weight loss.

Additionally, people who naturally wake up earlier tend to squeeze in more exercise compared to those who stay up late. A study in Finland found that early risers managed about 30 minutes more of physical activity daily for men, and about 20 minutes more for women, than their night-owl counterparts.

Exercising early can also help people feel accomplished, which has positive psychological effects. According to Jack Raglin, an exercise psychologist, morning workouts can provide a mood boost and give a sense of accomplishment, which can positively impact the rest of the day. Morning exercise also releases endorphins, the body's natural "feel-good" chemicals.

For those who want to burn more fat, exercising on an empty stomach before breakfast might be a good strategy. A 2019 study found that participants who exercised after an overnight fast burned twice the amount of fat compared to those who worked out after breakfast. They were also better at controlling their blood sugar levels, and adapted well to early exercise routines.

Javier Gonzalez, a co-author of the study and senior lecturer at the University of Bath, pointed out that exercising before breakfast isn’t for everyone. People with diabetes on insulin treatment, for instance, could face a higher risk of hypoglycemia if they exercise without eating. For healthy individuals worried about lacking energy for early workouts, Gonzalez suggested a cup of strong black coffee before exercising to make the session feel easier.

While morning workouts are frequently recommended for their practical and physiological benefits, it’s important to remember that exercising at any time of day is still beneficial for overall health. For example, evening exercisers may find it easier to combine strength training with cardio workouts since they are already warmed up from the day's activities.

Ultimately, the best time to work out is the time that fits best into your schedule. Whether you prefer to exercise early in the morning or late in the evening, staying active is crucial for both physical and mental well-being. What’s most important is consistency and choosing a time that allows you to form and maintain a regular habit.

Physical activity, at any time of day, provides a wide range of health benefits—so finding a routine that works for you is key to reaping these rewards.

Note: Materials provided above by The Brighter Side of News. Content may be edited for style and length.

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