These Are The Best Times To Exercise If You’re Managing Blood Sugar Or Weight Loss.

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The age-old question of whether it is better to exercise before or after meals for optimal weight loss and blood sugar control has intrigued scientists and fitness enthusiasts for a long time. What if I told you the answer depends on your goals? And what if you knew that science tells us that there are better or worse moments to exercise? Read on!

The Science Behind Fasted Exercise

A Japanese research team conducted work in this area, suggesting that exercising in a completely fasted state might be the most effective strategy for fat burning.

Our main finding was that exercise increased fat burning over 24 hours only when done after an overnight fast—when our body’s energy is at its lowest. Exercising before breakfast lowered the energy balance even more, creating a short-term energy deficit.

They boldly stated, “If exercise were a pill to burn body fat, it would be effective only when taken before breakfast or together with restricted food consumption.” (source). Despite this compelling claim, surveys indicate that few people actually exercise before breakfast.

To determine whether these 24-hour results translate into long-term weight loss, researchers conducted a study on experimental weight gain. Volunteers consumed up to 4,500 calories daily for six weeks while engaging in vigorous exercise for a total of 300 minutes per week.

Participants were divided into two groups: those who exercised after an overnight fast and those who exercised after a meal. A control group that did not exercise at all gained about 6.5 pounds. In contrast, the exercise-after-a-meal group gained around 3 pounds, while the pre-meal exercise group gained only about 1.75 pounds (source)

Weight Loss Studies and Their Findings

When it comes to weight loss, the results are less clear.

In a study involving twenty young women, participants were randomized into groups that exercised either before or after meals, while maintaining the same diets and exercise routines. Surprisingly, both groups experienced similar weight loss. The pre-meal exercise group did lose about an extra pound of body fat (3.5 lbs. vs. 2.2 lbs.), but this difference was not statistically significant and could have been due to chance (source).

Another study examined six weeks of low-volume, high-intensity interval training before or after meals, yielding similar results. One explanation for the lack of significant differences is that increased fat loss during pre-meal exercise might be “neutralized” by lesser diet-induced thermogenesis (source). In other words, the body may burn fewer calories processing food if eaten after exercise compared to before.

The Metabolic Tug-of-War

When we exercise after a meal, our bodies receive mixed signals. Exercise mobilizes energy stores for fuel, while eating focuses on assimilation and storage. This metabolic challenge, often referred to as a “hormonal tug-of-war,” might be responsible for the 15 to 40 percent greater calorie cost observed in some studies (source).

Some experts recommend exercising after meals to facilitate weight loss based on this theory. However, the actual calorie difference might only amount to 3 to 12 calories, which is minimal compared to the potential fat-burning benefits of pre-meal exercise, as indicated by the 24-hour fat balance studies showing up to a 500-calorie difference.

A New Perspective on Exercise Timing

A more plausible explanation for the mixed results in weight loss studies is that the clear body fat deficit achieved through pre-meal exercise might be offset by increased fat storage on non-exercise days.

The human body tends to hold onto extra fat when it can, compensating for the days when fat stores are not actively being reduced. Both of the failed weight loss studies had participants exercising only three days a week, allowing their bodies ample time to compensate on the remaining days.

To truly determine the effectiveness of pre-meal versus post-meal exercise, future studies should have participants exercise on most, if not all, days of the week. This approach could help maintain a consistent drive to reduce fat stores and provide more definitive answers.

Exercise Timing for Blood Sugar Control

For individuals with diabetes, the timing of exercise can have a significant impact on blood sugar control. Exercise helps muscles siphon off excess blood sugar, making it a beneficial strategy for those with elevated blood sugar levels. Research has shown that exercising after a meal can lower blood sugar levels as effectively as some blood sugar-lowering medications.

In a study involving type 2 diabetics, participants were randomized to take a 20-minute leisurely stroll before dinner versus after dinner. The after-dinner group experienced a 30 percent reduction in their blood sugar spike, demonstrating the importance of tactical timing. Even a 10-minute walk after a meal can make a difference in blood sugar control (source).

Optimal Exercise Timing

Blood sugar from a meal begins to appear in the bloodstream 15 to 20 minutes after the first bite, peaks around the one-hour mark, and returns to pre-meal levels within a few hours. For optimal blood sugar control, prediabetics and diabetics should start exercising 30 minutes after the beginning of a meal and ideally continue for about an hour to cover the peak blood sugar period.

If choosing a single meal to exercise after, dinner would be the most strategic choice due to the circadian rhythm of blood sugar control, which tends to wane throughout the day. Ideally, breakfast should be the largest meal of the day, followed by exercise. However, exercising after every meal would provide the most comprehensive benefits for blood sugar management.

Practical Recommendations for Exercise Timing

Given the evidence, the best approach to exercise timing may vary depending on individual goals—whether they are focused on weight loss or blood sugar control.

For weight loss:

1. Fasted exercise benefits: Exercising in a fasted state, particularly before breakfast, may enhance fat metabolism and contribute to greater fat loss over time. If you’re aiming to lose weight, consider incorporating morning workouts before your first meal.
2. Consistency is key: To prevent the body from compensating on non-exercise days, aim to exercise most days of the week. This consistent approach can help maintain a steady reduction in fat stores.
3. High-Intensity Interval Training (HIIT): Incorporating HIIT can be effective for weight loss, regardless of whether it’s done before or after meals. The key is maintaining a regular exercise routine.

For blood sugar control:

1. Post-meal exercise: For those managing diabetes or prediabetes, exercising after meals can significantly improve blood sugar control. A simple 10-20 minute walk after eating can make a meaningful difference.
2. Timing matters: Start exercising about 30 minutes after the beginning of a meal to align with the peak blood sugar period. This timing helps to mitigate blood sugar spikes effectively.
3. Focus on dinner: If you can only exercise after one meal, choose dinner. Blood sugar control tends to decline throughout the day, making post-dinner exercise particularly beneficial.

Conclusion

The timing of exercise can play a crucial role in achieving specific health goals, whether it’s weight loss or blood sugar control. While exercising in a fasted state before breakfast shows promise for enhancing fat metabolism, the benefits for weight loss over the long term require further investigation with more consistent exercise routines.

For individuals with diabetes or prediabetes, post-meal exercise, especially after dinner, can significantly improve blood sugar levels. A simple walk after meals can be an effective strategy for managing blood sugar spikes.

Ultimately, the best exercise timing depends on individual health goals and lifestyle. By understanding the science behind exercise timing, individuals can make informed decisions to optimize their workouts for better health outcomes.