Summary: High-intensity interval training (HIIT) burns more fat than aerobic exercise, a new study suggests.
Source: Victoria University of Melbourne
“If that stubborn body fat won’t go away, consider adding high-intensity interval training, or HIIT, to your exercise routine,” says Professor Zeljko Pedisic of Victoria University in Melbourne.
HIIT increases fat burning more than aerobic exercise, according to a study published in 2012 British Journal of Sports Medicine.
How was the research conducted?
The study authors pooled the results of 18 controlled intervention studies on the effects of HIIT on the rate of fat burning during exercise.
The intervention studies included a total of 511 adult participants who participated in supervised HIIT, moderate-intensity aerobic exercise, or a non-exercise control group.
The duration of the exercise interventions ranged from 2 to 14 weeks. In almost all studies, participants participated in three HIIT sessions per week.
What are the main findings?
A few HIIT sessions a week will turn your body into a fat burning machine. HIIT will allow you to start burning more fat not only during HIIT sessions, but also during other types of physical activity, such as brisk walking, swimming and sports.
Fat metabolism will improve after just four weeks of HIIT and will continue to improve over time.
After 12 weeks of HIIT, each minute of physical activity is expected to burn an additional 0.13 grams of fat. A person who does 150 minutes of physical activity a week can burn about 10 kg of extra fat over a decade.
Overweight individuals can expect a greater increase in fat burning compared to “normal” weight individuals.
Although individuals could also improve fat metabolism by engaging in aerobic exercise (such as jogging), this would require much more time and the improvements would be smaller.
Why is this important?
These findings could help the more than two billion overweight people (external link) in the world improve their fat metabolism and lose weight.
They can also help billions of others prevent unwanted weight gain over time.
“According to the latest Global Fitness Trends Survey (external link), HIIT is one of the most popular types of exercise. If you’re not already doing it, maybe you should give it a try,” concludes Professor Pedisic.
About the research news for this exercise
Original research: Closed access.
“Effects of high-intensity interval training (HIIT) and sprint interval training (SIT) on fat oxidation during exercise: a systematic review and meta-analysis”, by Muhammed M Atakan et al. British Journal of Sports Medicine
Effects of high-intensity interval training (HIIT) and sprint interval training (SIT) on fat oxidation during exercise: a systematic review and meta-analysis
To investigate the effects of high-intensity interval training (HIIT) and sprint interval training (SIT) on exercise-induced fat oxidation (FatOx) and how they compare to the effects of moderate-intensity continuous training (MICT).
A systematic review and meta-analysis.
Academic Search Ultimate, CINAHL, Online Digital Library of Theses and Dissertations, Open Access Theses and Dissertations, OpenDissertations, PubMed/MEDLINE, Scopus, SPORTDiscus, and Web of Science.
Eligibility criteria for choosing studies
Studies using a between-group design in adult non-athletes evaluating the effect of HIIT or SIT on FatOx (compared to no exercise or MICT) were included.
Eighteen studies of good to good quality were included; nine compared HIIT or SIT with no exercise and eleven compared HIIT or SIT with MICT. A significant overall effect of these types of interval training on FatOx was found (mean difference g/min (MD) = 0.08; 95% confidence interval (CI) 0.04 to 0.12; Mr<0.001). A significant effect was found for exercise regimens lasting ≥ 4 weeks and increased with each additional week of training (b= 0.01; 95% CI 0.00 to 0.02; Mr=0.003). HIIT and/or SIT were slightly more effective than MICT (MD=0.03; 95% CI 0.01 to 0.05; Mr=0.005). The effect on FatOx was greater in overweight/obese individuals.
HIIT or SIT can improve FatOx, with greater effects expected in longer training regimens and in overweight/obese individuals. Although some of the effects appear small, they may be important in holistic approaches to improve metabolic health and manage obesity.