I get many questions about HIIT benefits for fat burn, with or without ephedrine, so let’s detail a bit.
Just in case: HIIT stands for High Intensity Interval Training.
In terms of weight loss, HIIT seems « too good to be true ». Bodybuilders and other athletes love it because they can spend less time with cardio sessions 🙂
What Is HIIT Exactly?
As the name suggests, it’s a physical training made of short intervals of high intensity exercise followed by longer intervals of moderate or even low intensity exercise.
Is HIIT Really Effective for Fat Burn?
Yes, Interval Training and especially High Intensity Interval Training is probably the most efficient physical activity for fat burn, as proven by several medical studies since years. The most famous one has been conducted in 1994 by Angelo Tremblay et al.: « Impact of Exercise Intensity on Body Fatness and Skeletal Muscle Metabolism » which stated than « the decrease in the sum of six subcutaneous skinfolds induced by the HIIT program was ninefold greater than by the Endurance-Training program ». Another research made by Gibala et al. concluded that 2.5 hours of sprint interval training resulted in the same biochemical changes in muscle than 10.5 hours of endurance training. See what I mean?
Why Is It So Effective?
I won’t to go into details, here it is in 2 words: it has to do with your metabolism and energy consumption during and after your session.
When stressed by maximal effort, your muscle will start a chain reaction: it will use glycogen as fuel and will break it down to produce glucose, glucose produces pyruvate, and pyruvate associated with oxygen will produce water and carbon dioxide and release energy – this is known as the Krebs cycle.
Now a refresher about aerobic and anaerobic exercises: aerobic means with the use of oxygen for energy needs during your exercise and anaerobic means that your oxygen demand is higher than your oxygen supply during a short period of time.
To come back to our point (chain reaction initiated by your muscle at highest intensity) you see that oxygen is used by pyruvate, but in case of shortage of oxygen (thus anaerobic) carbohydrate turns short rapidly (because pyruvate ferments into lactate, you know, this burning sensation in your muscle) and then the interesting part: the last available energy resource now is fat cells! Your body has to increase the fat metabolism in order to destock your fat and use it for energy.
HIIT Benefits for Fat Burn: #1
How does that link to HIIT? well, HIIT is the best possible way to maximize the total time spent in the anaerobic mode. In fact, when you alternate high-intensity muscle effort with recovery periods, your total anaerobic time is much higher than compared to a one-time period at maximal effort (remember this lactate “burning feeling” that stops you very rapidly – try to sprint at your max speed and you will see how much distance you cover, compared to a succession of short sprints followed by short recovery periods).
HIIT Benefits for Fat Burn: #2
This one is a blessing: anaerobic exercise builds additional muscle mass. Cool 🙂 This is very important in case of diets for weight loss, where usually people lose essentially their muscle mass, which is key to burning calories even at rest. Which leads us directly to the next point.
HIIT Benefits for Fat Burn: #3
It has to do with something called EPOC: excess post-exercise oxygen consumption. Medical studies have shown that HIIT increases the Resting Metabolic Rate (RMR) for the next 24 hours, way longer than with a steady-state aerobic two-hours run. In other words: your HIIT session is shorter than your run but the fat burning effect will last longer.
HIIT Benefits for Fat Burn: #4
HIIT will improve your VO2max, which is so famous by runners and represents your maximal oxygen consumption.
HIIT Benefits for Fat Burn: #5
Again based on medical research, HIIT has been shown to suppress appetite more than low intensity exercises.
HIIT Benefits for Fat Burn: #6
And we stop here: the effects of HIIT on metabolism result in a significant reduction of insulin resistance and a better glucose tolerance, thus preventing type-2 diabetes.
Let’s sum up these HIIT benefits for fat burn:
with High Intensity Interval Training you build muscle, you stay longer in the anaerobic mode which in total burns more fat than long aerobic exercises, due to a higher Resting Metabolic Rate in the next 24 hours. Other positive effects: VO2max improvement, appetite reduction and various improvements on metabolism.
The only drawback I see is that it is very demanding: if you’re not exhausted after your session, it was not high intensity. Most overweight people would be wise to start with low intensity cardio sessions and see how it goes after a few months, before thinking of HIIT.