Why HIIT is highly effective for weight loss

I’ve been doing a bit of digging around to find the science behind HIIT. A fascinating commentary I’m reading at the moment presents some findings about HIIT that are simply amazing. It’s been suggested that we are actually consuming fewer calories but getting bigger, therefore decreased energy expenditure is blamed for the rise in obesity and overweight. While it is true that our lifestyles are generally sedentary, and some of us don’t even do light intensity exercise, could it be that we’re not doing the right exercise? HIIT (where we exercise at 80-90% of our maximal effort, as opposed to moderate intensity exercise which is at say 50-60% of maximal effort) appears to increase the energy we expend while resting (yes, that’s right, burn calories while sitting down!) for up to 72 hours. This might be because:

• different muscle fibres are being used
• stabilising muscles are being used during the intense exercise
• adrenaline is released
• the heart and lungs are getting a fantastic workout
• muscle is being built (as opposed to during moderate intensity aerobic exercise, eg walking or moderate jogging, during which no new muscle is built)
• more fat is being burnt

…and this astounding fact – the fitter you are, the more calories you burn while exercising, or even while walking to the bus stop, carrying your baby or groceries, brushing your teeth…!

I am not sure at this point if many studies have directly compared HIIT to lower intensity exercise, but I will post about that as soon as I find out.