Want to burn more fat? Try high intensity, interval training over traditional cardio exercise.
Anyone who knows me knows that I have long been a proponent of high intensity, short duration, interval training for fat loss and cardiovascular exercise as opposed to low to moderate intensity, long duration, steady state training. HIIT (High Intensity Interval Training), as I will call it or abbreviate it for this article, is a type of exercise that utilizes short, high intensity intervals interspersed with short periods of rest or low intensity exercise. In short, think sprint, walk, sprint, walk, sprint, walk, etc. HIIT is very effective for fat loss and one of the best things is it doesn’t take very long.
A study published this year of school age children showed that in just 2 to 3 days a week with just 6 minutes of work produced significant reductions in body fat percentage, body mass index and waist circumference as well as increases in muscle mass and improvements in V02 max (a measure of cardiorespiratory fitness). Low to moderate intensity, steady state, long duration (MOD) training on the other hand has not shown to be as effective for fat loss.
From a study from the Journal of Obesity in 2010, “The effect of regular aerobic exercise on body fat is negligible. Emerging research examining high-intensity intermittent exercise (HIIE) indicates that it may be more effective at reducing subcutaneous and abdominal body fat than other types of exercise. Most exercise protocols designed to induce fat loss have focused on regular steady state exercise such as walking and jogging at a moderate intensity. Disappointingly, these kinds of protocols have led to negligible weight loss.”
One of the reasons low to moderate intensity, steady state, long duration (MOD) training is so ineffective for fat loss is the body becomes very efficient at conserving energy at it after a while. It will start to burn less and less calories to perform the same amount of exercise. Also, if the duration and frequency of exercise are high enough it can start to elevate cortisol in the body which can age the body, inhibit fat burning, break down muscle and compromise the immune system among other things.
One of the big reasons people have believed they needed to do MOD training is for cardiovascular and aerobic fitness and overall health. In fact, HIIT has been shown to be just as effective if not more than MOD for cardiovascular and aerobic fitness as well as overall health.
From a study by the British Journal of Sports Medicine from June, 2019
“HIIT programs, when compared with MOD, promote greater increases in VO2max, ventricular and endothelial function, greater or comparable improvements in insulin sensitivity and blood pressure, lower ratings of perceived exertion, similar or higher levels of enjoyment, and similar or higher adherence than MOD, depending on how the program is designed. In addition, despite lower training volume in sprint interval training (SIT) programs, SIT may promote increases in skeletal muscle oxidative capacity, specific metabolic adaptations during exercise and exercise performance similar to MOD.
Decreases in body fat may be similar or higher in interval training than MOD. Interval training may elicit greater weight loss even if the energy expenditure obtained during the interval training is lower or equal to that during MOD. This may be due to greater resting energy expenditure and fat utilization immediately following interval training exercise.”
The last sentence from the above quotes from the study lead to another reason why HIIT is so effective for fat loss. HIIT training increases or elevates post exercise oxygen consumption (EPOC). EPOC is the increased calorie and fat burning post exercise. This is basically like the after burn effect. I tell people to think of driving their car real fast and then letting their foot off the gas. The car will coast afterwards for a long period of time if you do not apply the break. This is kind of similar to how EPOC works and it appears the intensity of exercise is the key factor for increasing it. If the HIIT is done correctly EPOC can stay elevated for 24 hours or longer after exercise.
With my clients I provide 2 of the high intensity interval training workouts free of charge on Saturday and Sunday morning. They take 15 minutes or less and if done correctly that is plenty to get the right effect. I do them in small circuits of exercises in 30 second intervals with 30 seconds rest after (1 to 1 work to rest ratio) with 7 exercises in the circuit. We then rest a minute and do second round of the circuit.
In the beginning we started with only doing half of the second round of the circuit because it was so difficult. We then progressed to doing the full second circuit.
Here is how I setup the circuit
1) Battle ropes for 30 seconds
Rest 30 seconds
2) Sled pushes for 30 seconds
Rest 30 seconds
3) Medicine ball slams for 30 seconds
Rest 30 seconds
4) Rapid step ups for 30 seconds
Rest 30 seconds
5) Dual action (arms and legs) stationary bicycle for 30 seconds
Rest 30 seconds
6) Shuttle run (sprints, side shuffles, back pedal) for 30 seconds
Rest 30 seconds
7) Sledge hammer swings on tire for 30 seconds
Rest 1 minute, repeat
A couple key points to mention.
- Everyone has their own starting point and if someone is very out of shape I might not even be able to have them do one of these workouts. They have to work up to it. Also, even if someone is able to do them they may have to start doing only 1 circuit or start with longer rest to work intervals. For example, I set this workout up in 1 to 1 work to rest intervals. A person may have to start with 1 to 2 work to rest ratios (example, 15 seconds of work to 30 seconds of rest) or even 1 to 3 work to rest ratios. A person can then work their way up. Each person needs to assess their health and fitness level and see what their starting point is.
- To get the right effect the exercises need to be performed as close to maximal effort as possible. If someone isn’t pushing themselves they won’t get the right effect. Intensity is the key factor. Again, keep in mind that everyone’s starting point and fitness level is different. Starting with all out or near maximal effort may not be appropriate for everyone, especially at first.
Keep the exercises simple. Since these exercises are being done at or near maximal effort and in a fatigued state you don’t want to do exercises that are complex and require a lot of coordination and technique. Exercises such as Olympic lifts, squats, dead lifts and other big multi joint movements should be avoided as in a fatigued state the form will start to slip causing the exercise to be done incorrectly.
- This setup is just how I set this program up. There are a bunch of different ways to set high intensity, interval training workouts up. The key is to do short periods of high intensity work interspersed with short periods of rest.
Below is a list of several peer reviewed research studies on the positive effects of high intensity, interval training with the key points in bold print.
From the Journal Frontiers in Physiology, December 2018
Title: Effects of High-Intensity Interval Training (HIIT) vs. Sprint Interval Training (SIT) on Anthropometric Measures and Cardiorespiratory Fitness in Healthy Young Women
In a 8 week study of high intensity interval training and sprint interval training with women in their 30’s showed that both methods of interval training produced reductions in body fat and waist circumference and improvements in cardiovascular fitness (V02 max) even though no changes in diet were made by the test subjects. What was interesting was that the sprint interval group also had reductions in BMI (Body Mass Index) and body weight and greater fat loss even though their total exercise time was significantly less at 23 minutes per session compared to 33 minutes for the high intensity interval group. Both types of interval training produced fat loss in a time efficient exercise manner.
From the abstract of the study
“Eight weeks of HIIT and SIT resulted in improvements in anthropometric measures and cardiorespiratory fitness, even in the absence of changes in dietary intake. In addition, the SIT protocol induced greater reductions than the HIIT protocol in the sum of skinfolds. Both protocols appear to be time-efficient interventions, since the HIIT and SIT protocols took 33 and 23 min (16 and 2 min of effective training) per session, respectively.”
From the Journal of Obesity, November 2010
Title: High Intensity Intermittent Exercise and Fat Loss
Here are some of the excerpts
“The effect of regular aerobic exercise on body fat is negligible; however, other forms of exercise may have a greater impact on body composition. For example, emerging research examining high-intensity intermittent exercise (HIIE) indicates that it may be more effective at reducing subcutaneous and abdominal body fat than other types of exercise. Regular HIIE has been shown to significantly increase both aerobic and anaerobic fitness. HIIE also significantly lowers insulin resistance and results in a number of skeletal muscle adaptations that result in enhanced skeletal muscle fat oxidation and improved glucose tolerance.”
“Most exercise protocols designed to induce fat loss have focused on regular steady state exercise such as walking and jogging at a moderate intensity. Disappointingly, these kinds of protocols have led to negligible weight loss.”
From the International Journal of Obesity, January 2008
Title: The effects of high intensity intermittent exercise training on fat loss and fasting insulin levels on young women
The study compared women exercising doing high intensity intermittent exercise (HIIT) vs steady state exercise.
Some the results of the study.
“Both exercise groups demonstrated a significant improvement in cardiovascular fitness. However, only the HIIE group had a significant reduction in total body mass (TBM), fat mass (FM), trunk fat and fasting plasma insulin levels. There was significant fat loss (P<0.05) in legs compared to arms in the HIIE group only. HIIE three times per week for 15 weeks compared to the same frequency of SSE exercise was associated with significant reductions in total body fat, subcutaneous leg and trunk fat, and insulin resistance in young women.”
From the Journal Metabolism, October 2010
Title: Effect of 2 weeks of sprint interval training on health-related outcomes in sedentary overweight/obese men.
The study investigated the effects of very high intensity sprint interval training (SIT) on metabolic and vascular risk factors in overweight/obese sedentary men over 2 weeks. The subjects completed 6 session (3 a week) of 4 to 6 repeats of 30 second sprints on a cycle ergometer with 4.5 minutes recovery between each sprint cycle. Significant decreases in waist and hip circumferences were observed after the 2 weeks.
From the abstract of the study
“2 weeks of SIT substantially improved a number of metabolic and vascular risk factors in overweight/obese sedentary men, highlighting the potential for this to provide an alternative exercise model for the improvement of vascular and metabolic health in this population.”
From the Journal Metabolism, July 1994
Title: Impact of exercise intensity on body fatness and skeletal muscle metabolism.
From the abstract of the study
“Two different modes of training on body fatness and skeletal muscle metabolism was investigated in young adults who were subjected to either a 20-week endurance-training (ET) program (eight men and nine women) or a 15-week high-intensity intermittent-training (HIIT) program (five men and five women). The mean estimated total energy cost of the ET program was 120.4 MJ, whereas the corresponding value for the HIIT program was 57.9 MJ. Despite its lower energy cost, the HIIT program induced a more pronounced reduction in subcutaneous adiposity compared with the ET program. When corrected for the energy cost of training, the decrease in the sum of six subcutaneous skinfolds induced by the HIIT program was ninefold greater than by the ET program. Muscle biopsies obtained in the vastus lateralis before and after training showed that both training programs increased similarly the level of the citric acid cycle enzymatic marker. On the other hand, the activity of muscle glycolytic enzymes was increased by the HIIT program, whereas a decrease was observed following the ET program. The enhancing effect of training on muscle 3-hydroxyacyl coenzyme A dehydrogenase (HADH) enzyme activity, a marker of the activity of beta-oxidation, was significantly greater after the HIIT program. In conclusion, these results reinforce the notion that for a given level of energy expenditure, vigorous exercise favors negative energy and lipid balance to a greater extent than exercise of low to moderate intensity. Moreover, the metabolic adaptations taking place in the skeletal muscle in response to the HIIT program appear to favor the process of lipid oxidation. "
From the British Journal of Sports Medicine, June 2019
Title: Is interval training the magic bullet for fat loss? A systematic review and meta-analysis comparing moderate-intensity continuous training (MOD) with high-intensity interval training (HIIT).
In this study they reviewed 36 different research studies comparing moderate intensity continuous training (MOD) to high intensity interval training (HIIT) for fat loss.
Study conclusion: Interval training and MOD both reduce body fat percentage (%). Interval training provided 28.5% greater reductions in total absolute fat mass (kg) than MOD.
From the Journal of Exercise Science and Fitness, May 2019
Title: Feasibility of incorporating high-intensity interval training (HIIT) into physical education programs to improve body composition and cardiorespiratory capacity of overweight and obese children: A systematic review
This study looked at 6 separate studies on adolescents 12 and under (3 studies) and from the ages of 12 to 18 (3 studies) to see if it was possible to incorporate high intensity interval training (HIIT) into physical education programs. What I found interesting is the HIIT protocols consisted of just 2 to 3 times a week with just 6 minutes of work and there were significant reductions in body fat percentage as well as increases in muscle mass.
Study Results: The HIIT protocols consisted of 2–3 sessions per week, with intervals of 15 s and passive or active rests of 15 s, totaling up to 6 min of work with 4 min of rest. The duration of HIIT programs was 6–24 weeks. Significant changes were reported in body composition, body mass index, body fat (%), waist circumference, and sum of skinfolds; and increases in muscle mass were observed. The inclusion of HIIT programs improved maximal oxygen uptake (VO2max), performance in the intermittent Yo-Yo test and maximal aerobic speed.