HIIT or LISS? Which One is Better for Fat Loss?
What is HIIT?
First things first, HIIT is the abbreviation of High Intensity Interval Training. The premise of HIIT is to alternate between short work and rest periods. However, the work periods are designed to be high-energy exercise at up to 95% of your max heart rate. For instance, you might decide to sprint on a treadmill as fast as possible for 30 seconds, walk for 30 seconds and then sprint again. Other popular HIIT workouts include circuit training, Tabata and football.
What is LISS?
LISS, on the other hand, stands for Low-Intensity Steady State or Low-Intensity Sustained State. LISS involves performing an aerobic activity at a low intensity for a prolonged period. The idea is to avoid rest during a 30-60 minute workout to help you maintain a moderate heart rate of around 40-60%. Which workouts are classed as LISS workouts, you ask? Well, dancing, jogging, rowing, aerobics and swimming, to name a few.
HIIT Versus LISS
Even though LISS is the most common form of cardio, there’s always the question of whether it’s better than HIIT for fat loss. The truth is, there are two types of cardiovascular endurance: aerobic and anaerobic. Aerobic endurance is associated with LISS because it produces energy using a continuous supply of oxygen. This allows your body to deliver oxygen to your muscles and engage them in activity without needing energy from another source. On the contrary, because anaerobic exercise (like HIIT) is performed at such a high level of intensity, your body demands more energy than your aerobic system can produce. It has to use its anaerobic system and the energy sources stored in your muscles, like ATP (adenosine triphosphate) and glycogen, instead of oxygen. This means that HIIT is ultimately more effective at burning fat. When you use LISS alone, the body will adapt quickly to the movement and its rhythmic cardio pattern. Therefore, the benefits are limited. In fact, one study discovered that 6-8 weeks of LISS achieved the same effects as just two weeks of consistent HIIT. That said, both LISS and HIIT will improve your physical fitness. You just have to work at 65% of your max heart rate (or higher) to reach the fat-burning zone — and this is very challenging with LISS. There is a catch with HIIT, though. This type of workout uses a lot more energy (calories) and requires more recovery time than LISS. That’s why you need to make sure that you don’t cut too many calories from your diet if you’re doing regular HIIT exercise. Otherwise, you risk losing valuable muscle mass.