Fat loss is one of the most common goals for those engaging in regular physical activity, but determining the most effective way to achieve it can be challenging. Two popular approaches to cardio are high-intensity interval training (HIIT) and steady-state cardio.
Both methods have their merits, and their effectiveness depends on various factors, including individual preferences, fitness levels, and goals. This article examines the science behind HIIT and steady-state cardio to determine which is more effective for fat loss, supported by evidence-based research.
What is HIIT?
HIIT involves short bursts of intense activity followed by brief periods of rest or low-intensity exercise. Sessions are typically shorter in duration, often lasting 15 to 30 minutes.
For example, HIIT workouts might include sprinting for 30 seconds, followed by 60 seconds of walking, repeated for several rounds. The focus is on maximising effort during the high-intensity intervals.
What is Steady-State Cardio?
Steady-state cardio refers to continuous, moderate-intensity exercise performed for an extended duration, typically 30 to 60 minutes or longer. Examples include jogging, cycling at a consistent pace, or brisk walking. The goal is to maintain a steady heart rate within a moderate intensity range (typically 50-70% of maximum heart rate).
The Science of Fat Loss: HIIT vs. Steady-State Cardio
Caloric Expenditure During Exercise
The number of calories burned during a workout is a critical factor in fat loss. Studies indicate that steady-state cardio can burn more calories than HIIT during the same workout duration because of the extended time spent exercising (Kang et al., 2014).
However, HIIT’s shorter duration can be more appealing to those with time constraints. Research by Boutcher (2011) highlighted that HIIT produces a greater caloric burn per minute due to the intensity of the exercise.
Excess Post-Exercise Oxygen Consumption (EPOC)
One of HIIT’s key advantages is its ability to induce excess post-exercise oxygen consumption (EPOC). This refers to the elevated calorie burn that occurs after the workout as the body restores itself to its resting state. A study by LaForgia et al. (2006) found that EPOC is significantly higher after HIIT than steady-state cardio, meaning HIIT can contribute to fat loss even after the workout has ended.
Fat Oxidation
Fat oxidation refers to the body’s ability to use fat as a fuel source during exercise. Steady-state cardio has been shown to promote fat oxidation due to the prolonged period of moderate-intensity effort (Achten et al., 2002). In contrast, HIIT relies more on carbohydrate metabolism during the workout but may still enhance fat oxidation in the hours post-exercise due to EPOC.
Muscle Preservation
Maintaining muscle mass is crucial during fat loss to ensure the weight lost is primarily from fat rather than lean tissue. HIIT has been found to be more effective in preserving muscle mass compared to steady-state cardio (Stöggl and Sperlich, 2014). The high-intensity intervals stimulate muscle fibres in a way similar to resistance training, which can help prevent muscle loss.
Hormonal Response
HIIT triggers a greater hormonal response that supports fat loss. Research shows that HIIT increases levels of human growth hormone (HGH), which plays a role in fat metabolism (Schoenfeld et al., 2013). Additionally, HIIT has been found to reduce insulin resistance more effectively than steady-state cardio, further supporting fat loss (Keating et al., 2017).
Practical Considerations for Fat Loss
Time Efficiency
One of HIIT’s most significant advantages is its time efficiency. For individuals with busy schedules, a 20-minute HIIT session can deliver comparable or even superior fat-loss results compared to 40-60 minutes of steady-state cardio (Gillen and Gibala, 2014).
Adherence and Enjoyment
Sustainability is crucial for long-term fat-loss success. Adherence often depends on personal preference. A study by Bartlett et al. (2011) found that while HIIT was perceived as more challenging, some participants enjoyed the variation in intensity compared to the monotony of steady-state cardio. Conversely, steady-state cardio may appeal to those who prefer a less intense, steady approach.
Risk of Injury
The intense nature of HIIT can increase the risk of injury, particularly for beginners or individuals with pre-existing conditions. Proper form and a gradual introduction to HIIT are essential to minimise this risk. Steady-state cardio, being less intense, generally poses a lower risk of injury and may be more suitable for beginners (Riebe et al., 2018).
Combining HIIT and Steady-State Cardio
Rather than viewing HIIT and steady-state cardio as mutually exclusive, combining both methods may offer the best results for fat loss. For example, incorporating 1-2 HIIT sessions and 2-3 steady-state sessions per week allows individuals to reap the benefits of both approaches while reducing the risk of overtraining or injury.
Which is Better for Fat Loss?
The answer to whether HIIT or steady-state cardio is better for fat loss depends on individual circumstances and preferences. HIIT offers superior time efficiency, EPOC, and hormonal benefits, making it ideal for those with limited time or who seek rapid results. However, steady-state cardio promotes sustained fat oxidation, lower injury risk, and may be easier for beginners to maintain long-term adherence. Ultimately, the best approach is the one an individual can sustain consistently while complementing other elements of their fitness regimen, such as strength training and nutrition.
Conclusion
Both HIIT and steady-state cardio are effective for fat loss, and their effectiveness depends on the individual’s goals, fitness level, and preferences. HIIT provides time-efficient workouts with additional post-exercise calorie burn, while steady-state cardio offers prolonged fat oxidation and a lower risk of injury. Combining both methods can optimise fat-loss outcomes and provide variety in training.
Key Takeaways Table
Bibliography
Achten, J., Gleeson, M. and Jeukendrup, A. E. (2002) ‘Determinants of the variability of heart rate during submaximal exercise’, Medicine and Science in Sports and Exercise, 34(10), pp. 1573-1578.
Bartlett, J. D. et al. (2011) ‘High-intensity interval running is perceived to be more enjoyable than moderate-intensity continuous exercise: Implications for exercise adherence’, Journal of Sports Sciences, 29(6), pp. 547-553.
Boutcher, S. H. (2011) ‘High-intensity intermittent exercise and fat loss’, Journal of Obesity, 2011, Article ID 868305.
Gillen, J. B. and Gibala, M. J. (2014) ‘Is high-intensity interval training a time-efficient exercise strategy to improve health and fitness?’, Applied Physiology, Nutrition, and Metabolism, 39(3), pp. 409-412.
Kang, J. et al. (2014) ‘Comparison of energy expenditure during single bouts of high-intensity interval training and steady-state aerobic exercise’, Journal of Strength and Conditioning Research, 28(10), pp. 2733-2741.
Keating, S. E. et al. (2017) ‘The effects of high-intensity intermittent exercise training on abdominal fat loss in overweight young women’, Medicine and Science in Sports and Exercise, 47(1), pp. 105-113.
LaForgia, J., Withers, R. T. and Gore, C. J. (2006) ‘Effects of exercise intensity and duration on the excess post-exercise oxygen consumption’, Journal of Sports Sciences, 24(12), pp. 1247-1264.
Riebe, D. et al. (2018) ‘ACSM’s Guidelines for Exercise Testing and Prescription’, 10th edn. Philadelphia: Wolters Kluwer.
Schoenfeld, B. J., Aragon, A. A. and Krieger, J. W. (2013) ‘Effects of meal frequency on weight loss and body composition: A meta-analysis’, Nutrition Reviews, 73(2), pp. 69-82.
Stöggl, T. and Sperlich, B. (2014) ‘The training intensity distribution among well-trained and elite endurance athletes’, Frontiers in Physiology, 5, p. 33.
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