HIIT is often touted by trainers and doctors as one of the most effective forms of exercise for fat loss, but the scientific evidence to back it up has been a little spotty so far. A new comprehensive review in the British Journal of Sports Medicine set to fix that. Researchers looked at 36 studies (and over 1,000 people) to figure out just how effective HIIT is when it comes to losing fat, especially when compared to steady-state or moderate-intensity activities.
The studies involved in the review varied widely; in most of them, body fat changes weren't even the focus. But researchers made sure to only collect data from research that lasted at least a month and that measured body composition at both the beginning and end of the trial. The moderate-intensity exercise routines included activities like walking, jogging, cycling, and swimming. The HIIT workouts included intervals of a few minutes of 80 percent max heart rate, according to Runner's World, as well as some even shorter ones — just a few seconds each — of all-out effort. Researchers called these latter intervals "sprint-interval training," or SIT.
HIIT Workouts Burned 29 Percent More Body Fat
HIIT was more effective for fat loss, the review found, and researchers could even put a number on it: the HIIT participants lost about 29 percent more fat than those doing moderate-intensity workouts. But they also pointed out that, despite that difference, both kinds of exercise led to fat loss, sometimes even in comparable amounts. HIIT participants, for example, lost 1.5 percent of their total body fat, compared to 1.4 percent for those doing moderate-intensity work.
So if you're looking to shed pounds, and especially fat, it's fair to say that either form of exercise is a good choice, whether you're plugging miles on the treadmill or sweating in a HIIT class. And there are other factors to consider when choosing a form of exercise as well. HIIT is harder on your body, so you shouldn't do it every day, especially if you're prone to injury. And everyone's body is different; moderate-intensity cardio might just work better for you in terms of weight loss and overall health. (Try this treadmill walking workout to get started.) After all the current numbers have been crunched, it's good to know the differences in effectiveness, but it still comes down to what works best for you.