- Being physically active at any time (morning, noon, or night) promotes well-being and offers health benefits.
- Early birds reap slightly more benefits from morning workouts than night owls who exercise later in the day.
- Many lifestyle factors influence why A.M. exercisers manage weight better than people who exercise in the P.M.
- Vigorous physical activity (VPA) at any time of day lowers type 2 diabetes risk.
Doing moderate-to-vigorous physical activity (MVPA), such as brisk walking or slow jogging at any time of day, promotes well-being and influences weight management. That said, two new studies on how exercising at different times of the day affects MVPA's benefits suggest that morning exercise may be slightly more beneficial than working out later in the day.
Morning MVPA Is Linked to Better Weight Management
The first study (Ma et al., 2023), published on September 4, is based on a cross-sectional analysis of 5,285 people who were in the habit of doing daily moderate-to-vigorous physical activity either in the morning (n = 642), midday/afternoon (n = 2,456), or evening (n = 2,187).
First author Tongyu Ma of Franklin Pierce University's Health Sciences Department and colleagues found that people with a diurnal (i.e., daily) pattern of doing at least 150 minutes of morning MVPA each week tended to have a lower BMI and waist circumference than those in the afternoon or evening clusters who did the same amount of cardio later in the day.
"The diurnal pattern of MVPA influences the association between MVPA and obesity. The promising role of morning MVPA for weight management warrants further investigation," the authors write in their paper's conclusion. The authors note that randomized clinical trials and prospective studies are needed to confirm the initial findings of this cross-sectional analysis. Cross-sectional data only provides a snapshot of a short time period and doesn't show how various lifestyle factors interact over time.
This cross-sectional analysis of the link between morning MVPA and better weight management is purely correlative and doesn't imply causation. It's possible that "morning larks" who consistently exercise earlier in the day have more predictable schedules than "night owls" and that other lifestyle factors and daily habits—beyond the time of day they're doing cardio—influence their weight management advantage.
Morning Activity Significantly Lowers Type 2 Diabetes Risk
The second study (Tian et al., 2023), published on September 20, quantifies the relationship between doing various intensities of physical activity in the morning, afternoon, or evening and people's risk of type 2 diabetes.
This cohort study conducted by a team of researchers affiliated with Harvard University and Harvard Medical School used data from 93,095 UK Biobank participants without a history of type 2 diabetes who wore an accelerometer that monitored their daily movements 24/7 for one week. Seven years later, the researchers did a follow-up to see which people had developed type 2 diabetes.
The accelerometer data was converted into metabolic equivalent of task (MET) units that were categorized into three time-of-day clusters: morning (06:00–12:00 hours), afternoon (12:00–18:00 hours), and evening (18:00–24:00 hours).
The researchers found that non-vigorous morning physical activity, such as walking at a slow pace, was associated with a 10 percent risk reduction of type 2 diabetes, and afternoon exercise at the same level of exertion was associated with a 9 percent reduced risk of type 2 diabetes. Light or easy physical activity in the evening wasn't associated with a noteworthy reduction in type 2 diabetes risk.
Notably, doing vigorous physical activity (VPA) was linked to lower type 2 diabetes risk across all times of day. Tian et al. summarize these findings, "Vigorous activity is associated with lower risk no matter the time of day of activity."
Also, when people are in the habit of doing vigorous exercise on a daily basis, other lifestyle factors have less of an impact on the association between the timing of daily physical activity and diabetes risk. "Adding lifestyle factors to the VPA models did not make a sizable difference in the substitution models for morning, afternoon, and evening associations," the authors explain.
Morning Exercise Only Provides "Slightly" Bigger Benefits
Finding time to exercise at any time of day can be challenging. If you're not an "early bird" or "morning lark" who likes to exercise at the crack of dawn—or if your morning schedule is too chaotic to squeeze in a workout—don't fret.
On average, the enhanced benefits of working out in the morning are relatively small compared to doing the same amount of exercise later in the day. For example, morning activity only lowered type 2 diabetes risk by 1 percent more than afternoon activity (10 percent vs. 9 percent).
If you want to optimize cardiovascular exercise's long-term health benefits, staying moderately active throughout the week and sustaining your motivation to exercise vigorously a few times a week (at any time of day that fits your schedule) should be the focus of your habit formation.
Disclaimer: This blog post isn't intended as medical advice. Always speak to a healthcare provider before kickstarting any exercise regimen, especially if vigorous physical activity that significantly elevates heart rate and makes you short of breath isn't currently a part of your daily routine.
Tongyu Ma, Thomas Bennett, Chong-Do Lee, Mairead Wicklow. "The Diurnal Pattern of Moderate-to-Vigorous Physical Activity and Obesity: A Cross-Sectional Analysis." Obesity (First published: September 04, 2023) DOI: 10.1002/oby.23851
Caiwei Tian, Charlyne Bürki, Kenneth E. Westerman & Chirag J. Patel. "Association Between Timing and Consistency of Physical Activity and Type 2 Diabetes: A Cohort Study on Participants of the UK Biobank." Diabetologia (First published: September 20, 2023) DOI: 10.1007/s00125-023-06001-7