Wondering whether you should choose HIIT or cardio for fat loss? While both HIIT and steady-state cardio work, the former is more time-efficient. High-intensity interval training, or HIIT, can easily fit into a busy schedule and burns massive calories.
What Is HIIT?
HIIT is a workout method that alternates between high-intensity exercise and lower-intensity training or active/passive recovery. The intervals can last anywhere from 20 seconds to one minute, depending on the HIIT protocol. A Tabata workout, for example, involves 20 seconds of all-out effort followed by 10 seconds of rest. One round takes just four minutes.
This training method can be applied to both strength and cardiovascular exercises. For example, you can sprint for 30 seconds, walk for another 30 seconds and repeat. If you prefer resistance training, you may use free weights or body-weight exercises for your HIIT workout.
Compared to steady-state cardio, HIIT is less time-consuming. The Mayo Clinic recommends using this workout strategy for about 15 minutes, three times a week. Due to its short duration, HIIT tends to be more enjoyable and easier to stick to. Would you prefer to spend one hour on the treadmill or get things done in as little as 15 minutes?
As the Mayo Clinic notes, HIIT workouts are just as good as or even better than traditional cardio. Over time, you may gain strength and endurance, improve your athletic performance and get leaner overall.
With a few exceptions, most people can benefit from high-intensity interval training. Generally, those with arthritis, joint injuries or back problems should get a doctor's approval before adding HIIT to their workouts. A health professional may recommend exercise modifications to prevent injuries. Likewise, discuss with your doctor if you have heart disease, hypertension or other chronic disorders, advises the Mayo Clinic.
HIIT vs. Cardio for Fat Loss
Should you do HIIT or running for fat loss? What about HIIT versus cycling or other aerobic activities? It depends. First of all, you don't have to choose between the two. HIIT can be used while running, cycling, rowing and so on. Second, both methods are effective. It all comes down to your preferences and availability.
If, say, you have a busy lifestyle, then HIIT is the way to go. But you can still do steady-state cardio on weekends or whenever your schedule allows for it. If you have joint pain or prefer a more relaxed workout, you can train at a lower intensity.
A February 2018 review published in Sports Medicine indicates that HIIT is a time-efficient strategy to lose fat. Subjects who used this method while cycling or running experienced a significant reduction in total body fat, visceral fat and abdominal fat mass.
HIIT running was more effective than HIIT cycling for reducing total body fat, while lower intensities (below 90 percent maximum heart rate) produced better results in terms of abdominal and visceral fat loss. Visceral adipose tissue has been linked to heart disease, dementia, colorectal cancer and other ailments, so it's in your best interest to get rid of it.
Read more: The 7-Minute Cardio-Sculpting Workout
In a small study, both HIIT and moderate-intensity continuous training reduced body fat mass and visceral fat in obese young women. Subjects experienced a 10 percent decrease in total and regional fat mass in as little as 12 weeks. The steady-state cardio group spent twice as much time working out compared to the HIIT group. These findings were published in the Journal of Diabetes Research in January 2017.
As the scientists note, HIIT is more time-efficient due to the increase in post-exercise oxygen consumption. With this training method, your body consumes more oxygen post-workout (EPOC) to return to its normal state. The duration and magnitude of EPOC is greater when you're training at high intensity compared to moderate-intensity exercise. As a result, you'll burn more calories after leaving the gym.
Additionally, high-intensity interval training may increase the release of growth hormones and other compounds that influence fat loss, reports the above review. The more intense your workout, the greater this effect will be.
Potential Health Benefits of HIIT
When it comes to HIIT versus cardio, both training methods can improve cardiovascular health and sports performance. However, high-intensity interval training appears to be more effective, according to a small study featured in the journal Lipids in Health and Disease in September 2013.
Researchers compared endurance training, high-intensity circuit training and low-intensity circuit training. Overweight men who engaged in high-intensity circuit training had greater reductions in body fat, blood pressure, triglycerides and cholesterol levels compared to the other two groups. All subjects experienced major improvements in body weight.
HIIT may also benefit those with diabetes, suggests a January 2015 review published in the journal Diabetes Spectrum. As the researchers point out, low- to moderate-intensity activities, such as walking, may not be vigorous enough to improve cardiorespiratory fitness. More vigorous exercise, on the other hand, may produce better results in terms of aerobic endurance and glycemic control.
In clinical trials, HIIT has been shown to be effective at improving cardiovascular health, blood pressure, insulin response and other health markers, according to the Diabetes Spectrum review. Just one HIIT session may reduce blood sugar after a meal in older adults with diabetes. This training method may also increase muscle insulin sensitivity for 24 to 48 hours after exercise.
The benefits of HIIT may also include improved stroke volume, faster recovery from vigorous workouts, lean mass gains and greater muscle definition, states the American Council on Exercise. Plus, it appears to be safe and beneficial for those with heart disease, notes the Mayo Clinic.
However, this doesn't mean that HIIT is suitable for everyone. Researchers recommend seeing a doctor before getting started with this kind of workout, especially if you suffer from diabetes. Those with a sedentary lifestyle should start slowly and increase the intensity gradually. Also, note that most studies had small groups of participants, so further investigation is needed to confirm the long-term safety and effectiveness of HIIT.
Is HIIT Right for You?
There are some things to consider before getting started with HIIT. If you're out of shape, it's safer to start with steady-state cardio or strength training to build up your conditioning. Keep your fitness level in mind when choosing the best exercises for your HIIT workout.
As the Mayo Clinic points out, high-impact HIIT activities may not be safe for people with poor movement patterns, weak muscles or injuries. Instead, they should opt for low-impact HIIT options, such as biking or water running.
Beware that HIIT is taxing on the body and central nervous system. To stay safe, limit your HIIT workouts to no more than three weekly sessions on non-consecutive days, recommends the American Council on Exercise. Sure, if you're an athlete, you may do more — but that's another story.
For the average person, a well-rounded workout routine that incorporates resistance training and two or three weekly HIIT sessions is more than enough. Again, it's important to consider your fitness level and overall health.
Read more: The Truth Behind 5 Common Myths About HIIT
The American Council on Exercise states that it's possible to work out the day after a HIIT session, but you should opt for less intense activities and target different muscle groups. For example, if you do HIIT on the treadmill, you may work your upper body the next day. If you use a rowing machine or arm ergometer for HIIT, consider training your legs or glutes the day after.
Due to its intense nature, this training method is more likely to cause muscle soreness and aches. Deconditioned individuals are more likely to experience these problems. There is also a higher risk of muscle strains when you do HIIT, warns the American Council on Exercise.
The best way to avoid injuries is to watch your form and choose exercises that match your fitness level. If you're planning to combine HIIT and strength training, use lower weights and watch your lifting form. Listen to your body and try not to go overboard. Remember, you can always slow down and switch to steady-state cardio to keep burning calories.
Maximize Your Fat-Burning Potential
Whether you choose HIIT or cardio for fat loss, there are some things you can do to get faster results. Ideally, use these training methods as part of a complete workout plan that also includes strength, flexibility and balance training.
Weight lifting is particularly important, as it helps build and preserve muscle, leading to a faster metabolism. Lean mass uses energy compared to adipose tissue, states the University of New Mexico. Muscle mass accounts for about 20 percent of total daily energy expenditure. Body fat makes up just five percent of the number of calories burned daily.
The U.S. Department of Health and Human Services recommends at least two strength-training sessions per week, so that's a good start. Depending on your preferences, you can perform strength exercises and HIIT or cardio on the same day or separate days. Another option is to do full-body circuits that combine strength and aerobic activities.
Last, watch your diet and calorie intake. Nutrition and exercise are equally important for fat loss and overall health. Certain foods, especially those rich in protein and healthy carbs, can fuel your workouts and maximize fat burning.
Protein, for example, keeps your metabolism up and increases satiety while preserving lean mass. Carbohydrates, on the other hand, help replenish your glycogen stores and give you the energy needed for a heart-pounding workout.
Get your calories from whole and minimally processed foods. Chicken or turkey breast, fish, seafood and low-fat dairy are all great sources of protein. Start your day with oatmeal for an energy boost. Fill up on lean protein and carbs after exercise to speed up muscle repair. Consider eating your carbs around your workouts when your body can use them for fuel rather than storing them as fat.
- Mayo Clinic: "Infographic: High Intensity Interval Training (HIIT)"
- Mayo Clinic: "Mayo Clinic Q and A: Incorporating HIIT Can Be Effective Way to Become More Fit"
- Sports Medicine: "Effect of High-Intensity Interval Training on Total, Abdominal and Visceral Fat Mass: A Meta-Analysis"
- Journal of Diabetes Research: "Comparable Effects of High-Intensity Interval Training and Prolonged Continuous Exercise Training on Abdominal Visceral Fat Reduction in Obese Young Women"
- Lipids in Health and Disease: "Effects of High-Intensity Circuit Training, Low-Intensity Circuit Training and Endurance Training on Blood Pressure and Lipoproteins in Middle-Aged Overweight Men"
- Diabetes Spectrum: "Effectiveness and Safety of High-Intensity Interval Training in Patients With Type 2 Diabetes"
- American Council on Exercise: "8 Reasons HIIT Workouts Are So Effective"
- Mayo Clinic: "Why Interval Training May Be the Best Workout at Any Age"
- Mayo Clinic: "Sprint, Rest, Repeat: Exploring the Benefits of High-Intensity Interval Training"
- American Council on Exercise: "Steady State Vs. Interval Training: Which One Is Best for Your Clients?"
- University of New Mexico: "Controversies in Metabolism"
- U.S. Department of Health and Human Services: "Physical Activity Guidelines for Americans"
- British Journal of Nutrition: "Dietary Protein – Its Role in Satiety, Energetics, Weight Loss and Health"
- U.S. Anti-Doping Agency: "Carbohydrates: The Master Fuel"