Forget crunches and hours spent on treadmills. The secret to a slimmer waistline may start in the gym, but cruising through your cardio session isn’t doing you (or your tummy!) any favors. As a matter of fact, science says that interval training may be more effective at helping you lose weight than steady-state cardio. (No gym membership? Here’s how to flatten your belly without a lick of exercise.)
A review and meta-analysis published in the British Journal of Sports Medicine analyzed more 75 studies involving more than 2,000 people. Each study compared interval training—working at quick bouts of high-intensity effort, followed by short rest periods—to continuous effort exercise at a moderate intensity for at least four weeks. Turns out, those who turned to interval training reduced their overall fat mass by 28.5% more than those who did continuous, lower-intensity exercise. (Read more about the benefits of high-intensity exercise as compared to straight cardio.)
Many different types of interval training were included in the meta-analysis, but Albert Matheny, RD, nutritional advisor to Promix
Matheny says to keep in mind that there is no definitive work-to-rest ration for high-intensity interval training (or HIIT), so see what works for you. “The main parameters are intense exercise, which could be 10 seconds or a few minutes, with alternating intervals of rest or very low-intensity exercise,” he says. “In general, I would recommend working above 80% of your max heart rate for the interval, and no longer than 20 minutes maximum of a training session. The goal during rest is to get your heart rate down around 60% of your max.”
An important caveat for anyone who wants to try HIIT for the first time: It’s not for everyone and requires a familiarity with any exercise you’re doing. “Due to its high-intensity nature, you should have some familiarity with exercise in general, and specific experience in the movements you will be doing for your HIIT workout,” Matheny says. “Also, as with anything, like driving a car, when you first learn to do something you should not be doing it as fast as possible, which is often required as part of a HIIT workout. The faster you go, the more your heart rate will go up. The reason is when you learn a movement you need to practice performing it correctly at a slow speed before trying to do it as fast as you can in a HIIT setting.” If you’ve never run stairs or done squat jumps, don’t use that as your first HIIT exercise. Stick to what you know.
As a bonus, intervals allow you to focus on different muscle groups as you switch between exercises, which gives certain muscles time to recover while you fire up others. Get started with these 8 exercises that will flatten your belly, without a single crunch.