HIIT VS. LISS CARDIO FOR WEIGHTLOSS

With so much information (and misinformation) floating around the internet these days, it can be hard to filter out the opinion from fact.  When it comes debating HIIT Vs. LISS, we have to look at the science to really know which is best for losing body fat.

“YOU SHOULD ALWAYS BE DOING LOTS OF LONG CARDIO SESSIONS BRO”

The common misconception begins when people learn that during the first 6 minutes of exercise we burn primarily ATP and glucose for energy, and by the 40 minute mark we end up burning 40% fat for fuel.  Doesn’t that make working out for longer time the key? Yes and no. To this day, I still see dozens of bodybuilders prepping for competition doing HOURS of LISS (Low Intensity Steady State) cardio, walking at slow pace on a treadmill with a hoodie on for nearly 2-3 hours at a time. First of all, a dramatic increase in cardiovascular activity has been shown to help fat burning in trainded individuals for up to 3 weeks, then suddenly drops off as the body quickly adapts.  Secondly, although you can burn fat while performing long bouts of cardio, in most cases it pales in comparison to HIIT (High Intensity Interval Training.  A study was done on HIIT vs LISS training showed that when an athlete performs Wingate interval training (All out exertion with hardly any oxygen), it increased the athlete’s metabolism by 50% and kept it extremely high for hours on after training!  This is due to a heavily increased EPOC, which is known as Post Exercise Oxygen Consumption, which is directly related to exercise intensity. The higher the EPOC, the more calories you burn throughout the rest of the day. For example, this means that even just 20 minutes of extremely high intensity sprints with short rest breaks can burn more fat than an hour of steady state cardio. Not only that, but the same study confirmed that doing long term cardio will actually LOWER your metabolism and calories burned throughout the day by removing our unconscious or involuntary movements such as tapping our feet, moving our fingers, arms, getting up to walk to the kitchen, going to the bathroom etc. One of the most important things observed is that people who train longer and longer tend to move less throughout the rest of the day, due to the mental and physical fatigue. This lack of movement costs people up to 1500 calories that aren’t burned PER DAY. And as you now know, this would completely throw off your metabolic rate calculations.

Next, prolonged overuse of cardiovascular training can almost entirely halt production of your Thyroid T3 hormone, Testosterone AND Growth Hormone, causing a catabolic effect that severely inhibits muscle growth, which inhibits fat loss. Another hormone thrown into the mix is cortisol. Cardio increases cortisol levels, which is your stress hormone. Also, during high stress situations, when serotonin is lower and cortisol is high, you crave high sugar foods.

It is important to realize that quite often in the long term, overuse of long bouts of cardio will most likely lead to muscle loss (The scale shows your losing weight, but you’re not losing fat, mostly muscle!). Remember, the more muscle you have, the more calories you burn while you are at rest in order to keep the tissue alive (An extra 10lbs of muscle = 500 extra calories burned per day!). So if you begin to lose muscle, but you don't change your diet accordingly, you will gain fat (Caloric intake stays the same, but caloric need goes down = Fat gain)

This being said, for overweight individuals or beginners, the first 15 weeks of higher cardiovascular activity DOES hold better fat loss results! BUT your body adapts VERY quickly to cardio because it looks for the easiest way to use the least amount of oxygen and energy, even while working at your greatest capacity. And this doesn't promote fat loss!

To sum this up, a massive analysis of nearly 500 studies was compiled and the results are as follows: A positive change in diet is far more effective in fat loss than introducing cardio into your workout regime. From time to time you might find me at the track doing sprints, but you will NEVER catch me doing steady state cardio. But most of all, stick to high intensity interval weight training at the gym.

For an ectomorph body type such as my own, HIIT makes the most sense.  For you, its might be best to do your own research and see where it works in best for you and your body.

Hope this helps!

Denon Maximchuk

Social: Denon Maximchuk

Science Resources:

https://www.ncbi.nlm.nih.gov/pubmed/17101527

https://www.ncbi.nlm.nih.gov/pubmed/28513103

https://www.ncbi.nlm.nih.gov/pubmed/28401638

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC29916...

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC52374...

https://www.ncbi.nlm.nih.gov/pubmed/16380698

https://www.ncbi.nlm.nih.gov/pubmed/16380698

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