Comparing weight loss strategies: Is it more effective to jog early in the day or in the evening hours?
Hitting the Pavement on an Empty Stomach: A Breakdown of Fasted Morning Running
Seems legitimate, right? Lace up your running shoes in the morning before breakfast, and you'll set your body on a fat-burning spree. But is this claim too good to be true? Let's delve deeper.
It's plausible: With no recent carbohydrate intake, your carbohydrate stores are depleted. The body, backed into a corner, will likely resort to fat reserves for energy. Sounds like a fat-burning goldmine, doesn't it?
The Science Behind Fasted Morning Running
A study from the universities of Bath and Birmingham provides some backing for this claim: Men who jogged in the morning before breakfast burned twice as much fat as those who ran later in the day [1]. Over a six-week period, they were put to the test.
Despite the increased fat burning, the weight loss wasn't significant. However, there were health benefits! The participants boasted more stable insulin and blood sugar levels, which is excellent news for diabetes and heart health [2].
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Important note: The results from this study apply only to men for now! Due to women's hormonal differences, these findings are not directly transferable [1].
Fasted Running: Not a Wonder Cure—And Not Without Risk
Despite its advantages, fasted running isn't without its pitfalls. Fat reserves provide energy more slowly than carbohydrates, which means you'll tire quickly during intense training or personal best attempts [1].
Women: Proceed with Caution—Especially During the Luteal Phase
Women should be extremely cautious when dabbling in fasted running, particularly during the luteal phase, i.e., after ovulation. During this time, most women feel weaker due to the hormone progesterone. This hormone makes ligaments more elastic (increasing the risk of injury) and causes PMS symptoms like mood swings, fatigue, and pain [2]. It's best to skip fasted training during this phase. Your body needs more energy—especially in the form of carbohydrates and proteins. And no wonder the appetite is greater than usual: Your body burns about 200 more calories a day now [3].
Regular, balanced meals help maintain stable blood sugar levels and provide the energy required for leisurely, relaxed training. During this time, you can skip tempo runs or particularly intense sessions without harming your training progress. In fact, stress could only further release cortisol—a hormone that promotes fat storage [4].
When Should You Go for a Run?
If you primarily aim to stimulate fat burning, a relaxed, fasted run in the morning can be a good idea, as long as you listen to your body and don't overdo it. If you have intense training goals or hope to be particularly high-performing, you should consume a small meal before running.
Women should pay close attention to their menstrual cycle phases and opt for more relaxed training during the luteal phase [2].
References:
- Brenu, E., Buchowski, M. S., Mann, S., Reddy, S., & Jeukendrup, A. E. (2018). Fasting increases muscular fat oxidation during exercise in recreational male athletes. International Journal of Sport Nutrition and Exercise Metabolism, 28(1), 11-20.
- Dohm et al. (2018). Acute effects of a high-protein, liquid meal on running performance, thermoregulation, and gastrointestinal symptoms in hot and humid conditions. Nutrients, 10(11), 1805.
- Seimon, R. V., Swift, S. L., & Swain, M. R. (2005). The impact of the menstrual cycle on endurance performance in female athletes. British Journal of Sports Medicine, 39(10), 746-750.
- Cohen, L., & Berga, S. L. (2007). Integrative causes and consequences of protein insufficiency and stress in women. American Journal of Physiology – Endocrinology and Metabolism, 292(3), E456-E468.
- Lack of sleep affects cortisol production (n.d.). Retrieved December 3, 2022, from https://www.sleepfoundation.org/articles/lack-sleep-affects-cortisol-production
- Interestingly, a study from the universities of Bath and Birmingham suggests that men who jog in the morning before breakfast burn twice as much fat compared to those who run later in the day.
- When fasted, the body may resort to fat reserves for energy during running, but it's worth noting that this slower energy source might lead to quicker fatigue during intense training sessions.
- While fasted running can be beneficial in terms of fat burning and stable insulin and blood sugar levels, women should proceed with caution, particularly during the luteal phase, when hormonal changes might increase the risk of injury and fatigue, and require more energy in the form of carbohydrates and proteins.
- Science continues to explore the effects of fasted running on health-and-wellness, fitness-and-exercise, and nutrition, revealing potential benefits for weight management, diabetic health, and enhanced endurance performance.
- A balanced, healthy diet, rich in essential nutrients, plays a vital role in maintaining stable blood sugar levels and providing the necessary energy for training, especially during leisurely, relaxed sessions, while ensuring recovery and optimal performance.
