High-intensity interval training, or HIIT [1], is the darling of the workout world. It's easy to see why: it's quick by definition, usually lasting no longer than 30 minutes; easily done with bodyweight moves [2] and home workout-ready; and it's crazy effective at burning calories [3] and getting you into shape.
If losing belly fat is your goal, hearing all the hype about HIIT might make you wonder if it's a good option for targeting fat around your midsection. The answer? While you can't spot reduce fat anywhere on your body, you certainly can reduce overall body fat through workouts, and our experts agreed that HIIT is one of the most effective ways to do it.
"Reducing belly fat comes down to burning as many calories as possible through exercise," said exercise physiologist and personal trainer Tom Holland [4], MS, NSCA-CSCS, ACSM. When you're doing HIIT, "the idea is that you're pushing your cardiovascular system and your metabolic system at a much higher rate than you normally would," explained Michael Fredericson, MD, professor and director of physical medicine and sports medicine at Stanford University. That gives you a number of weight loss benefits.
You Burn Calories After Your Workout
The high-intensity nature of a HIIT workout means you're torching a significant number of calories as you're working out — but both experts agreed that the calorie burn continues after the workout as well, thanks to post-exercise oxygen consumption [6] (EPOC). This is the phenomenon that occurs as your body returns to a normal metabolic rate following a workout. To do that, your body pulls in more oxygen than it usually would while you're at rest; to process that excess oxygen, your body needs to burn more calories, even when you've stopped working out.
HIIT workouts "are like a switch," Fredericson told POPSUGAR. "They really turn on your metabolic system. It's processing at a very high rate, and it takes a while for that to calm down." According to the American Council on Exercise, HIIT is the most effective way [7] to get this afterburn effect, which Fredericson said can last for up to six hours.
HIIT Targets Belly Fat Specifically
Beyond this overall fat-burning effect, Holland told POPSUGAR that there is some evidence to suggest that HIIT may reduce abdominal fat in particular. A 2018 meta-analysis by French researchers showed that "HIIT significantly reduced total, abdominal, and visceral fat mass [8]" (the fat stored around your abdominal organs), confirming findings from a smaller Italian study from 2016 that a combination of HIIT and steady-state workouts were the most effective in reducing fat around the midsection [9].
How Often Should You Do HIIT to Burn Belly Fat?
These kinds of benefits might make you want to jump into a six-days-a-week HIIT regimen, but both Fredericson and Holland cautioned against doing too much, too fast. "If you haven't tried HIIT before, ease into it, and see what your body can handle, because I've seen people get injured with it," Fredericson said. After you have a solid fitness base, he recommended working up to two or three HIIT workouts a week, each 20-30 minutes in duration. Try this 20-minute beginner's HIIT workout [10] to get started.
During your workout, you can maximise your belly fat burn by "pushing hard for a short duration, then recovering at a very comfortable intensity," Holland said, similar to the difference between sprinting and jogging. He suggested that beginners start with a 1:3 ratio of work to rest, doing 10 seconds of a hard interval followed by 30 seconds of recovery. Once you get more advanced, you can move up to a 1:2 or 1:1 ratio. During the hard intervals, Fredericson said, you should be out of breath enough that you'd have a hard time holding a conversation [12].
Diet will always play a big role when it comes to belly fat [13], but burning calories through consistent exercise is crucial as well, Holland said. Effective and efficient, HIIT is likely to give you good results. When paired with dietary changes, Fredericson said, "the fat just starts to drop off." Ready to get started? This 20-minute HIIT circuit [14] is designed to help you torch calories and burn away belly fat.