When deciding which form of cardio is ideal for weight-loss, steady state or HIIT, it's a good idea to start with the research. And research has shown time and time again that if your goal is to lose weight, HIIT is the best — and the quickest — way to get there.
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For example, consider the results of one International Journal of Obesity study: Researchers had one group of women perform 40 minutes of steady-state aerobic exercise, while another group alternated eight-second sprints with 12 seconds of recovery for 20 minutes. By the end of 15 weeks, women in the HIIT group lost as much as 7.3 pounds, while women in the steady-state group actually gained as much as 2.7 pounds.
And a more recent study in Journal of Diabetes Research shows similar positive HIIT results. Female subjects who did HIIT lost comparable amounts of abdominal fat as female subjects who performed moderate-intensity aerobic exercise. These results led study authors to argue that HIIT is superior for fat-loss due to its time efficiency, as both study groups followed their respective training programs for 12 weeks and burned equal amounts of calories during their exercise sessions.
Read more: HIIT Exercises at Home
Why HIIT Works
There are a few reasons why HIIT is the superior fat-loss exercise method. First, your body has to work harder to produce the adenosine triphosphate (ATP) your muscles need for energy, leading you to burn more calories during your workout.
Second, once your workout is over, your body will continue burning calories as it cools down. This is known as excess post-exercise oxygen consumption (EPOC), or the afterburn effect.
And finally, HIIT tends to break down more lean muscle tissue, which then needs to be built back up. As a result, your body will require more energy to help your muscle tissues recover and rebuild.
Read more: 5 Ways to Supercharge Your HIIT Routine
Do Both for Maximum Benefit
Give HIIT a try with this routine from the American Council on Exercise (ACE): First, choose an aerobic exercise (ex. cycling or running). After a five-minute warm-up at an easy pace, alternate one minute at a high intensity (think: seven to nine on a perceived exertion scale of one to 10) with two minutes at a moderate intensity (five or six on a scale of one to 10). Repeat for three or four total intervals and finish with a five minute cool-down.
Due to the intensity, you'll want to limit HIIT sessions to one to two times per week to avoid injury and burnout. On the other days, go for an easy walk or jog. After all, just because HIIT is superior for fat-loss, doesn't mean you can't or shouldn't do long-form aerobic exercise. Steady-state cardio — running in particular — offers many unique benefits.
One study01783-8/fulltext) in the American Journal of Cardiology found that aerobic exercise, which included jogging, cycling and elliptical trainers, was more effective for improving cardiometabolic health than resistance training.
Another study, this one from the Journal of Adolescent Health, reveals running for just 30 minutes in the morning during weekdays for three consecutive weeks was enough to boost subjects' mood and sleep quality. As an added bonus: A long-term study in Journal of the American College of Cardiology reveals that runners can expect to add three years to their life.
So long as you keep your intensity low-to-moderate (aim for an effort of five or six on a perceived exertion scale of one to 10), doing steady-state cardio on non-HIIT days — as opposed to lounging on the couch — will keep the blood flowing so you can flush out the metabolic waste that accumulated in your tissues the day before. This will help you recover faster so you can hit it hard again the next day.