What is the best exercise to lose weight? This question is asked a million times. Is there really any answer in black and white to this question. I myself have been swayed to the notion of a running movement, a cycling movement, Zumba movement etc. Whatever is in vogue and whatever a bunch of friends do seems to have a vanity factor too.
Finally given my schedule, age, attitude etc. I have discovered that finding out ‘Why I am doing’ ‘What I am doing’ is the best deal. Let me give you some of those insights backed by validated research. Your muscles have energy producing units called ‘Mitochondria’ and this is where ATP (Adenosine Tri Phosphate) are made and fats are burned. The more mitochondria and the more active they are, the greater is the oxidative capacity you have for fat loss. Now comes the question of how to increase our oxidative capacity? We then need a little brief of the difference between HIIT &LISS
HIIT is High Intensity Interval Training, which consists of short sprint intervals coupled with low to moderate intensity work, an eg; 10-30 sec sprint followed by a 1-3 minute walk and repeating it. LISS is low Intensity Steady State Cardio, which involves low to moderate intensity work, eg; walking on a treadmill or cycling while holding a conversation.
There are two ways in which our muscles burn glucose (blood sugar). Aerobic (with air), eg; long bouts of LISS and anaerobic (without air) eg; HIIT. There are two tests, which are good predictors of exercise capacity AT (Anaerobic threshold), & LT (Lactate threshold).
During HIIT, the AT & LT are high whereas in LISS they are below AT & LT.
This shows that HIIT style workouts improve our metabolism and we can expect more fat loss over time. In other words if we step-up intensity we are changing muscles metabolism, boosting caloric burn because we increase the mitochondrial density of our muscles.
Saying this slow cardio is not bad, it is just that our body is so adaptive and it is not challenging anymore. Lot of people walk everyday but do not really lose weight as their metabolism adjusts to low intensity. To complicate it if we are on LISS and low calorie diet it could cause muscle loss. It’s like a drug where our body creates a tolerance and needs higher doses for the same effect. Even worse is that many who hope to lose fat with cardio are also on a low calorie, low carb diets. This depletes the body’s stored glycogen (carb stored in muscle) then the body searches for new sources of energy; we might then tap into the muscle protein, not a great idea to lose muscle instead of fat.
So do we now have an answer?
HIIT is great for fat loss and revving up your metabolism while LISS is great for heart health, and muscle recovery. Combining the two for balance seems a great idea. HIIT cannot be done more than 2-3 times/week as it is high stress on CNS (Central Nervous System) and can cause burn out and requires proper guidance to avoid injury. LISS may be the only option for some who have certain medical/psychological issues. To conclude HIIT is quick, effective fat loss, increases metabolism, improves body composition and muscle retention, but is not suitable for all. LISS is safe, takes longer to achieve similar goals, and has no significant effect on metabolism.