In short:
- HIIT burns more calories during the workout, but strength training keeps your metabolism elevated for hours after the session ends.
- Meta-analyses show that both methods reduce body fat, but HIIT is often the more time-efficient option.
- Strength training builds muscle mass, which over the long term permanently speeds up your basal metabolic rate.
- The optimal strategy is to combine both types of training in one weekly plan.
HIIT vs strength training for fat burning is one of the questions asked most often in exercise science. The two methods activate different physiological mechanisms, and the choice depends on your goals, available time and training level. In this comparison article we analyze, based on the evidence, which approach is more effective for reducing body fat.
How do HIIT and strength training affect the mechanisms of fat burning?
Fat burning isn’t just about the calories spent during the workout — post-workout energy expenditure matters too. HIIT (high-intensity interval training) is based on alternating short, maximally intense intervals with recovery pauses. It triggers a considerable excess post-exercise oxygen consumption (EPOC): the body keeps burning calories at an elevated rate for another 2–24 hours after the session ends (LaForgia et al., 2006).
Strength training works differently. Micro-damage to muscle fibers and the recovery processes also require energy, but the EPOC window of strength training extends up to 48 hours. Even more important is the long-term effect: each additional kilogram of muscle mass raises basal metabolic rate by roughly 13 kcal per day (Westcott, 2012). This means that if you do strength training, your body works as a “fat-burning machine” even at rest.
Which method burns more calories during the workout?
In the short term, HIIT has the advantage. The systematic review and meta-analysis by Wewege et al. (2017) showed that HIIT reduces body fat percentage to a statistically significant degree on average and is more effective per unit of time than moderate continuous cardio. According to the same study, the calorie expenditure of a 20-minute HIIT session is comparable to 40 minutes of moderate exercise.
| Measure | HIIT | Strength training |
|---|---|---|
| Calories during the workout | High | Moderate |
| EPOC window | 2–24 hours | Up to 48 hours |
| Muscle mass gain | Minimal | Significant |
| Basal metabolic rate (long term) | Small change | Rises |
| Time per session | 20–30 min | 45–60 min |
| Suitability for beginners | Moderate | Good |
In a randomized 8-month study by Willis et al. (2012), three groups were compared: aerobic training only, strength training only, and a combination of the two. The absolute loss of fat tissue was greatest in the aerobic training group, but the improvement in body composition — preserving muscle mass and losing fat mass at the same time — was best in the combined group (Willis et al., 2012).
Is HIIT or strength training the better strategy for long-term fat loss?
In the long run, strength training has a clear advantage when it comes to speeding up metabolism. Strength training and aging is an especially important topic, because from our thirties onward muscle mass naturally declines (sarcopenia), slowing metabolism and making it harder and harder to maintain your body weight. Regular strength training effectively slows this process.
Women and strength training: part I tackles the common myth that strength training makes women “too muscular.” In reality, women’s testosterone levels are too low for that. Instead, strength training improves body composition, raises metabolism and supports bone density — all factors that also directly affect how effective fat burning is.
The NIH National Institute on Aging recommends regular strength training for people of all ages, precisely for managing body composition over the long term and supporting metabolism (NIH National Institute on Aging).
Are HIIT and strength training suitable for young people and children?
According to the evidence, both types of training are safe for younger people too. Strength training and children and Strength training and children explain that, contrary to popular belief, strength training doesn’t stunt children’s growth — it strengthens bones and joints and develops body awareness. Beginners and younger trainees, however, are advised to start with strength training, as it teaches correct movement patterns and lowers the risk of injury before moving on to HIIT programs.
What do studies say about combining the two?
Most sports scientists recommend combining both methods. A combined program produces a synergistic effect:
- HIIT improves cardiovascular fitness, boosts insulin sensitivity and burns calories efficiently
- Strength training builds muscle mass, raises basal metabolic rate and improves body composition over the longer term
A practical weekly plan is 2–3 strength workouts with 1–2 HIIT sessions and adequate recovery time. This approach is in line with the conclusion of Wewege et al. (2017) that a combined strategy gives the best results for reducing body fat and preserving muscle mass.
References
- LaForgia J, Withers RT, Gore CJ. (2006). Effects of exercise intensity and duration on the excess post-exercise oxygen consumption. J Sports Sci. PMID: 17101527
- Westcott WL. (2012). Resistance training is medicine: effects of strength training on health. Curr Sports Med Rep. PMID: 22310704
- Wewege M, van den Berg R, Ward RE, Keech A. (2017). The effects of high-intensity interval training vs. moderate-intensity continuous training on body composition in overweight and obese adults: a systematic review and meta-analysis. Obes Rev. PMID: 28401638
- Willis LH, Slentz CA, Bateman LA, Shields AT, Piner LW, Bales CW, Houmard JA, Kraus WE. (2012). Effects of aerobic and/or resistance training on body mass and fat mass in overweight or obese adults. J Appl Physiol. PMID: 22002084
Frequently asked questions
Which burns more fat — HIIT or strength training?
During a workout, HIIT burns more calories, but strength training keeps your metabolism elevated for longer after the session ends and builds muscle mass, which speeds up fat burning in the long term. The best results come from combining both.
How many HIIT workouts per week are recommended?
Most studies recommend 2–3 HIIT sessions a week, leaving at least one day between sessions for recovery. More doesn’t mean better results — overtraining increases the risk of injury and undermines your progress.
Does strength training slow down fat burning because muscle mass weighs more?
No. Muscle mass does weigh more than fat, but that is a positive change — a muscular body burns more calories at rest. Your body fat percentage goes down even if the number on the scale moves more slowly.
Which type of training is better for beginners who want to burn fat?
Beginners are advised to start with strength training, as it teaches correct movement patterns with a lower risk of injury. After 4–6 weeks of introductory training, you can gradually add HIIT intervals.
Can fat loss supplements improve the results of HIIT or strength training?
Supplements are an addition to, not a replacement for, training and balanced nutrition. Before using any supplement, look into its composition and the evidence behind it, and consult a healthcare professional if necessary.
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