What is HIIT?
HIIT stands for high intensity interval training; it consists of 10-30 second maximum effort intervals followed by 2-3 minutes of low intensity, low effort work. An example would be to sprint at maximum effort for 15 seconds, and then walk until you are able to catch your breath (2-3 minutes). Like weight training, HIIT cardio is considered anaerobic work while LISS (low intensity steady state) cardio is considered aerobic work.
Time Efficacy of HIIT
Many times the excuse people use for poor health is their lack of time. They don’t feel as if they are able to spend 30-60 minutes doing steady state cardio. HIIT is an excellent alternative because it achieves the same results (if not better) in a shorter timeframe. In addition to burning fat, there’s evidence supporting the fact that HIIT can increase your metabolic rate. What you get done in 40 minutes through the use of steady state cardio, you can get done in 20 minutes of HIIT.
Using HIIT for Fat Loss
When performing cardiovascular aerobic work, there isn’t a more optimal strategy than performing some form of HIIT. Studies have shown that HIIT leads to a big decrease in abdominal fat whereas LISS doesn’t. There are a few reasons for this. HIIT increases your mitochondrial capacity; mitochondria are structures in your muscle where ATP(adenosine triphosphate) are made and fats are burned, so the more you have and the more active they are, the greater your fat loss capacity will be. HIIT also gives you a 24 hour energy expenditure whereas LISS, because of it’s aerobic nature, does not.
As far as fat loss, there is not much difference between doing 30 minutes of steady state cardio to burn 300 calories or just cutting 300 calories out of your diet. When you do long bouts of LISS cardio, your body adapts and adjusts your metabolism so that it becomes dependent on the steady state cardio. When you try and cut the 30 minute session of LISS out, it’s as if you consumed an additional 300 calories because of your body’s adaptation. HIIT does not have this same issue so it is another reason why it’s the preferred method of cardio. However, just like any other training you do, there should be a build up. What I mean by this is you should not start off doing 3 HIIT sessions per week, and conversely, you should not go from doing 3 HIIT sessions per week to completely cutting it out. What you can do is just add or remove one session, one week at a time.
HIIT is one of the most optimal things you can do for fat loss aside from accurately monitoring your macro-nutrient intake.