Key Points of Fasted Cardio Benefits Fat Loss Article
- Many bodybuilders still believe fasted cardio benefits fat loss.
- Both fasted cardio and non-fasted cardio combined with calorie restriction effectively reduced body weight, body fat percentage, and waist circumference in overweight and obese young adult males.
- Fasted cardio significantly reduced fasting insulin levels and increased tissue cell sensitivity to insulin. However, there was no significant difference in the reduction of insulin levels between the fasted and non-fasted groups.
- There was no difference in fat loss between fasted and non-fasted cardio.
Have you heard about fasted cardio and wondered if it could be the key to shedding those extra pounds? Fasted cardio and intermittent fasting have long been popular ways to increase fat loss. In this blog, we will dive deeper into fasted cardio and discuss whether it can aid in weight loss. We will also explore the benefits and disadvantages of fasted cardio, including its impact on insulin sensitivity and fat burning, and discuss the risks involved in practicing it. So, are you ready to find out if fasted cardio benefits fat loss? Read on.
Fasted cardio involves exercising on an empty stomach first thing in the morning after an overnight fast to burn more fat since glycogen stores are depleted. While some studies suggest an early morning fast workout may lead to greater fat loss (Kim et al., 2015); however, other studies have found no benefit of a fasted cardio workout. (Schoenfeld et al., 2014a) The inconsistent findings in some studies may be due to differences in study duration, sample size, lack of calorie control (i.e., different energy balance between subjects), and subject demographics. Factors such as exercise intensity, duration, and frequency may also play a role in the observed benefits of a fasted workout or lack thereof.
Benefits of fasted cardio. (Insulin and Fasting)
Insulin suppresses fat burning, and low concentrations in the body during fasted exercise result in an increase in the rate of lipolysis (i.e., fat burning). When you work out in a fasted state, your body uses stored fat as fuel rather than glycogen from food. (Vieira et al., 2016) As a result, fasted cardio could lead to increased fat oxidation and potentially greater fat loss compared to fed cardio.
One study found that morning exercise after overnight fasting was more effective than post-breakfast exercise in reducing body fat. (Kim et al., 2015) Another study compared changes in body composition induced by fasted cardio or non-fasted cardio during Ramadan. The researchers randomized 19 men to the fasted exercise group and a fed exercise group (i.e., 40-60 minutes a week, three days a week for 30 days. At the end of the study, the researchers found varying degrees of weight loss in both groups. Still, only the fasted aerobic exercise group showed a significant decrease in body fat percentage.(Trabelsi et al., 2012)
Another potential benefit of fasting before cardio might enhance insulin sensitivity and glucose tolerance, making it an excellent option for individuals with blood sugar concerns. Moreover, incorporating fasted cardio into your workout routine could save you time while delivering endurance benefits like better aerobic capacity.
Fasted cardio can also have potentially negative outcomes, such as reduced energy during exercise (i.e., a reduction in the ability to perform high-intensity exercise) and low blood sugar levels (i.e., dizziness/lightheadedness), and some people have suggested increased hunger and overeating post-exercise. Some studies have found that fasted cardio reduces athletic performance. (Zouhal et al., 2020) Fasted cardio has also been shown to raise cortisol compared to fed-state cardio. (Kim et al., 2015) Additionally, fasted cardio may lead to a decrease in muscle mass. (Schoenfeld et al., 2014b)
Does fasted cardio aid weight loss? New Study Results
Fasted cardio could assist in weight loss by increasing fat burning, but the research has been inconclusive. A recent study re-examined the potential benefits of fasted cardio and whether it benefits fat loss.
The study involved thirty overweight and obese young adult males randomly divided into a fasted cardio group, a fed aerobic exercise group, and a control group. Both exercise groups underwent a six-week indoor treadmill intervention, combined with diet control, five days a week. The fasted cardio group exercised on an empty stomach and had breakfast half-hour after exercise, while the fed aerobic exercise group exercised 1 hour after breakfast. The control group did not have any intervention. The exercise physical activity heart rate was monitored using a Polar meter to control the exercise intensity.
Results and Interpretation
The results showed that both fed and fasted exercise significantly improved body shape in overweight and obese young adult males. Weight, body mass index (BMI), body fat percentage, waist circumference, hip circumference, waist-to-hip ratio, and waist-to-height ratio decreased significantly in both groups after the six-week experiment. However, there was no significant difference between the cardio on empty stomach and fed cardio groups regarding body shape improvement, suggesting that the timing of meals relative to exercise did not significantly affect the outcomes. (Liu et al., 2023)
Interestingly, the study found that fasted cardio group significantly reduced fasting insulin levels and increased tissue cell sensitivity to insulin. Fasted cardio may have additional benefits in improving insulin sensitivity, which is crucial for metabolic health. However, this does not directly translate to greater fat loss.
The study also monitored adverse reactions in the fasted and fed cardio groups. There was no significant difference in the frequency of adverse reactions between the two groups, indicating that cardio on am empty stomach did not lead to an increase in adverse effects compared to fed state cardio. This is an important consideration for those who might be concerned about the potential negative effects of exercising on an empty stomach.
The study by Liu et al. provides valuable insights into the effects of fasted and non-fasted aerobic exercise on body shape and biochemical indices in overweight and obese young adult males. The results suggest that while both fasted and fed exercise can significantly improve body shape and various health parameters, there is no significant difference in fat loss.
In conclusion, scientific evidence does not support the myth that fasted cardio is superior for fat loss. Fasted and non-fasted aerobic exercise can contribute to weight loss and improved health, and the choice between the two should be based on individual preferences and comfort. Whether you prefer to do your cardio session in a fed or fasted state is an individual preference.
Kim, T. W., Lee, S. H., Choi, K. H., Kim, D. H., & Han, T. K. (2015). Comparison of the effects of acute exercise after overnight fasting and breakfast on energy substrate and hormone levels in obese men. Journal of Physical Therapy Science, 27(6), 1929-1932. https://doi.org/10.1589/jpts.27.1929
Liu, X., He, M., Gan, X., Yang, Y., Hou, Q., & Hu, R. (2023). The Effects of Six Weeks of Fasted Aerobic Exercise on Body Shape and Blood Biochemical Index in Overweight and Obese Young Adult Males. J Exerc Sci Fit, 21(1), 95-103. https://doi.org/10.1016/j.jesf.2022.11.003
Schoenfeld, B. J., Aragon, A. A., Wilborn, C. D., Krieger, J. W., & Sonmez, G. T. (2014a). Body composition changes associated with fasted versus non-fasted aerobic exercise. Journal of the International Society of Sports Nutrition, 11(1), 54. https://doi.org/10.1186/s12970-014-0054-7
Schoenfeld, B. J., Aragon, A. A., Wilborn, C. D., Krieger, J. W., & Sonmez, G. T. (2014b). Body composition changes associated with fasted versus non-fasted aerobic exercise. Journal of the International Society of Sports Nutrition, 11(1). https://doi.org/10.1186/s12970-014-0054-7
Trabelsi, K., Abed, K. e., Stannard, S. R., Jammoussi, K., Zeghal, K. M., & Hakim, A. (2012). Effects of Fed- Versus Fasted-State Aerobic Training During Ramadan on Body Composition and Some Metabolic Parameters in Physically Active Men. International Journal of Sport Nutrition and Exercise Metabolism, 22(1), 11-18. https://doi.org/10.1123/ijsnem.22.1.11
Vieira, A. F., Costa, R. R., Macedo, R. C. O., Coconcelli, L., & Kruel, L. F. M. (2016). Effects of aerobic exercise performed in fasted v. fed state on fat and carbohydrate metabolism in adults: a systematic review and meta-analysis. British Journal of Nutrition, 116(7), 1153-1164. https://doi.org/10.1017/S0007114516003160
Zouhal, H., Saeidi, A., Salhi, A., Li, H., Essop, M. F., Laher, I., Rhibi, F., Amani-Shalamzari, S., & Ben Abderrahman, A. (2020). Exercise Training and Fasting: Current Insights. Open Access J Sports Med, 11, 1-28. https://doi.org/10.2147/oajsm.S224919