Debunking the HIIT Routine for Fat Loss: New Study Finds No Difference Summary
- The meta-analysis compared continuous aerobic exercise to the HIIT routine for fat loss. The study found that HIIT is not superior to constant aerobic exercise in reducing body fat percentage or abdominal visceral fat in individuals with excess weight. However, HIIT showed beneficial effects on cardiorespiratory fitness, total cholesterol, and fasting blood glucose compared to CAT.
- The effectiveness of HIIT and constant aerobic exercise in terms of body fat and abdominal visceral fat reduction does not appear to be significantly influenced by how many sessions participants undertook, their age, or their initial BMI. This suggests that these training methods could be similarly effective across a wide range of individuals, regardless of these specific factors.
High-Intensity Interval Training, or HIIT, has been hailed as a fast track to fat loss in the ever-evolving world of fitness and health. Using a HIIT routine for fat loss has become the gold standard for getting six-pack abs. But does it really stand up to the hype for fat loss? A groundbreaking study titled “High-intensity interval training is not superior to continuous aerobic training in reducing body fat: A systematic review and meta-analysis of randomized clinical trials” challenges this popular belief, offering new insights into the effectiveness of different exercise regimens for fat reduction.
Obesity and Exercise
Obesity, characterized by an excessive accumulation of body fat, is closely linked to a range of detrimental health issues, including insulin resistance, type 2 diabetes mellitus, dyslipidemia, atherosclerosis, systemic arterial hypertension, acute myocardial infarction, and stroke. (Zalesin et al., 2011) In Brazil, data from 2021 indicated that 57.2% of the population was affected by excess weight, with obesity rates at 22.4%. (da Silva et al., 2021) With the growing threat of obesity, researchers are looking for the optimum exercise program to reduce body fat. Using a HIIT routine for fat loss has become a viable way to reduce body fat in a shorter amount of time.
The Definition of HIIT
HIIT, or high-intensity interval training, involves brief but intense periods of physical activity followed by rest or recovery periods. These workouts typically alternate between the two, creating a work-rest pattern. By engaging in intense exercise for short periods, it has been suggested that many people struggling with weight loss should use a HIIT routine for fat loss. By engaging in HIIT sessions, individuals can enhance their cardiovascular endurance while spending a relatively short time on each exercise, making it an efficient option for busy schedules. Additionally, HIIT often incorporates bodyweight exercises like high plank positions, offering a diverse range of workout options to improve muscle size and strength.
Modes of Exercise For Fat Loss
Traditional aerobic exercises, such as Continuous Aerobic Training (CAT), involve moderate-intensity exercise ranging between 40% and 60–65% of maximal aerobic capacity; aerobic exercise is usually performed in conjunction with resistance exercises. They help improve body composition by reducing body fat and increasing lean mass. (Willis et al., 2012) CAT involves a longer time required to exercise.
HIIT typically involves short bursts of high-intensity activity interspersed with periods of rest. It is characterized by greater calories burned than CAT and is believed to result in greater body fat reduction due to higher VO2 max and excess post-exercise oxygen consumption (EPOC).(Gibala & Jones, 2013)
EPOC is often described as the “afterburn” effect following exercise. It’s like driving a car and turning off the engine, but it remains hot for a while. Similarly, after you finish exercising, your body continues to burn more calories than usual as it returns to its resting state. This happens because your body is restoring itself to pre-exercise levels, replenishing energy stores, and repairing muscle tissues. So, even after your workout, your body is still working hard, which means you’re still burning calories.
Review of Literature on HIIT Routines for Fat Loss
In examining the literature on the use of a HIIT routine for fat loss, there have been studies that have found that HIIT is superior for fat loss and others that have found reductions in body fat similar to CAT. For example, some studies have found HIIT to be superior to losing body fat compared to CAT. (Irving et al., 2008; Khodadadi et al., 2023; Ricardo Borges et al., 2019)
In a study conducted by Higgins et al. in 2016, HIIT was superior to CAT in achieving these goals, with CAT resulting in a decrease of 0.3% in % body fat and no change in android fat mass (i.e., Android fat mass refers to the distribution of body fat in the upper part of the body, particularly around the abdomen and trunk. Android fat increases the risk of heart disease, type 2 diabetes, and metabolic syndrome). HIIT led to a decrease of 1.0% in % body fat and a decrease of 0.2% in android fat mass. (Higgins et al., 2016)
However, others have found no benefit of a HIIT routine for fat loss compared to CAT. (Andreato et al., 2019; Keating et al., 2017) A 2018 study found no differences in the percentage of body fat and android fat between CAT and HIIT (CAT: Δ 0.1% and HIIT: Δ ‐ 0.3% for % BF, and CAT: Δ ‐ 1.1% and HIIT: Δ ‐ 0.1% for android fat), it is worth considering the potential reasons for these conflicting results may be due to the different types of exercise protocols employed (i.e., biking, treadmill, resistance exercise, etc).
Study Protocol and Results:
The new literature review examined the comparative effectiveness of a HIIT routine for fat loss compared to CAT in reducing body fat. Researchers conducted a systematic review and meta-analysis of randomized clinical trials, focusing on adults with excess body weight. The study included volunteers aged between 18 to 55 years who were all overweight. Out of the 11 studies included in the meta-analysis, six had an intervention duration of 12 weeks, while four studies had interventions lasting less than 12 weeks.
The results were eye-opening: HIIT and CAT had no significant difference regarding body fat reduction or android body fat. This result was consistent across both men and women, indicating that HIIT for fat loss was not superior to CAT for either gender in terms of body fat percentage reduction. However, HIIT showed a slight edge in improving VO2 max or aerobic capacity and reducing total cholesterol and fasting blood glucose.
The Implication of HIIT’s Effectiveness for Fat Loss
Challenging the widely held belief in the superiority of a HIIT routine for fat loss, study implications reevaluate the fat loss benefits of HIIT. With these implications calling into question the impact of HIIT on fat loss, further exploration is needed to understand the true effects better. The study brings to light the need for a deeper understanding of the mechanisms behind fat loss in relation to HIIT, challenging conventional perspectives and opening doors for future research.
For individuals and fitness professionals, this study underscores the importance of choosing exercise regimens based on personal preferences, goals, and medical considerations rather than following trends. Both HIIT and CAT can be effective components of a weight management program, with HIIT offering additional cardiovascular benefits. (Armstrong et al., 2022; Wang et al., 2022)
Given the similar effect of HIIT and CAT on reducing adiposity, exercise selection should rely on individual preferences, including exercise duration, tolerance to physical effort, motivation to exercise, and goals.
Conclusion
This comprehensive study has challenged the myth that a HIIT routine for fat loss is superior to conventional aerobic exercise. It reminds us that one size does not fit all in the realm of fitness. Whether it’s HIIT or CAT, the best exercise is the one that aligns with your lifestyle, preferences, and health goals.
References
Andreato, L. V., Esteves, J. V., Coimbra, D. R., Moraes, A. J. P., & de Carvalho, T. (2019). The influence of high-intensity interval training on anthropometric variables of adults with overweight or obesity: a systematic review and network meta-analysis. Obesity Reviews, 20(1), 142-155. https://doi.org/https://doi.org/10.1111/obr.12766
Armstrong, A., Jungbluth Rodriguez, K., Sabag, A., Mavros, Y., Parker, H. M., Keating, S. E., & Johnson, N. A. (2022). Effect of aerobic exercise on waist circumference in adults with overweight or obesity: A systematic review and meta-analysis. Obes Rev, 23(8), e13446. https://doi.org/10.1111/obr.13446
da Silva, L. E. S., Gouvêa, E., Stopa, S. R., Tierling, V. L., Sardinha, L. M. V., Macario, E. M., & Claro, R. M. (2021). Data Resource Profile: Surveillance System of Risk and Protective Factors for Chronic Diseases by Telephone Survey for adults in Brazil (Vigitel). Int J Epidemiol, 50(4), 1058-1063. https://doi.org/10.1093/ije/dyab104
Gibala, M. J., & Jones, A. M. (2013). Physiological and Performance Adaptations to High-Intensity Interval Training. In L. J. C. van Loon & R. Meeusen (Eds.), Limits of Human Endurance: 76th Nestlé Nutrition Institute Workshop, Oxford, August 2012 (Vol. 76, pp. 0). S.Karger AG. https://doi.org/10.1159/000350256
References
Higgins, S., Fedewa, M. V., Hathaway, E. D., Schmidt, M. D., & Evans, E. M. (2016). Sprint interval and moderate-intensity cycling training differentially affect adiposity and aerobic capacity in overweight young-adult women. Applied Physiology, Nutrition, and Metabolism, 41(11), 1177-1183. https://doi.org/10.1139/apnm-2016-0240 %M 27806634
Irving, B. A., Davis, C. K., Brock, D. W., Weltman, J. Y., Swift, D., Barrett, E. J., Gaesser, G. A., & Weltman, A. (2008). Effect of exercise training intensity on abdominal visceral fat and body composition. Med Sci Sports Exerc, 40(11), 1863-1872. https://doi.org/10.1249/MSS.0b013e3181801d40
Keating, S. E., Johnson, N. A., Mielke, G. I., & Coombes, J. S. (2017). A systematic review and meta-analysis of interval training versus moderate-intensity continuous training on body adiposity. Obesity Reviews, 18(8), 943-964. https://doi.org/https://doi.org/10.1111/obr.12536
Khodadadi, F., Bagheri, R., Negaresh, R., Moradi, S., Nordvall, M., Camera, D. M., Wong, A., & Suzuki, K. (2023). The Effect of High-Intensity Interval Training Type on Body Fat Percentage, Fat and Fat-Free Mass: A Systematic Review and Meta-Analysis of Randomized Clinical Trials. Journal of Clinical Medicine, 12(6), 2291.
Kramer, A. M., Martins, J. B., de Oliveira, P. C., Lehnen, A. M., & Waclawovsky, G. (2023). High-intensity interval training is not superior to continuous aerobic training in reducing body fat: A systematic review and meta-analysis of randomized clinical trials. Journal of Exercise Science & Fitness, 21(4), 385-394. https://doi.org/https://doi.org/10.1016/j.jesf.2023.09.002
References
Ricardo Borges, V., João Pedro Araújo, N., Victor Silveira, C., Claudio Andre Barbosa de, L., James, S., James Peter, F., & Paulo, G. (2019). Is interval training the magic bullet for fat loss? A systematic review and meta-analysis comparing moderate-intensity continuous training with high-intensity interval training (HIIT). British Journal of Sports Medicine, 53(10), 655. https://doi.org/10.1136/bjsports-2018-099928
Wang, S., Zhou, H., Zhao, C., & He, H. (2022). Effect of Exercise Training on Body Composition and Inflammatory Cytokine Levels in Overweight and Obese Individuals: A Systematic Review and Network Meta-Analysis. Front Immunol, 13, 921085. https://doi.org/10.3389/fimmu.2022.921085
Willis, L. H., Slentz, C. A., Bateman, L. A., Shields, A. T., Piner, L. W., Bales, C. W., Houmard, J. A., & Kraus, W. E. (2012). Effects of aerobic and/or resistance training on body mass and fat mass in overweight or obese adults. Journal of Applied Physiology.
Zalesin, K. C., Franklin, B. A., Miller, W. M., Peterson, E. D., & McCullough, P. A. (2011). Impact of Obesity on Cardiovascular Disease. Medical Clinics of North America, 95(5), 919-937. https://doi.org/https://doi.org/10.1016/j.mcna.2011.06.005
Additional Information on HIIT Routines for Fat Loss
The article on HIIT workouts emphasizes that High-Intensity Interval Training (HIIT) is a great way to achieve weight loss goals and build muscle mass in a shorter time, but it is not more effective for fat loss. By engaging in short bursts of intense exercise, followed by brief seconds of rest, HIIT training can elevate heart rate and enhance calorie burn in a shorter time. This fitness approach, which includes exercises like mountain climbers, burpees, and treadmill sprints, targets both upper-body and lower-body strength. It’s effective for improving muscle power and overall fitness level.
HIIT Routines for Fat Loss
HIIT exercises, often guided by a certified personal trainer, are structured with varying work and rest periods. These workouts can be adapted to any fitness level and often involve using dumbbells, barbells, etc. Alongside building muscle, HIIT training contributes to reducing belly fat and achieving a calorie deficit, key factors in weight loss.
In addition to weight training and cardio, HIIT workouts can help lower blood pressure and boost muscle group activation in areas like the lower back. A well-rounded workout plan incorporating HIIT can be the best way for quick, efficient fitness progress, especially when combined with guidance from a personal trainer to transition smoothly to the next exercise.
Are there any specific exercises that work best in a HIIT routine for fat loss?
No specific exercise works best for fat loss in a HIIT routine. The key is incorporating various exercises targeting different muscle groups and elevating your heart rate. This could include exercises like burpees, squats, lunges, mountain climbers, and high knees.