Cardio for fat loss: HIIT or LISS

Balivada Sravan Kumar
Balivada Sravan Kumar

 | 1 minute to read
Exercise Science

Bro Science has a lot of detractors – and rightly so. After all, its practitioners have advocated a wide range of fitness myths ranging from “Green Coffee Detoxs” to “Carbs Are Evil”, all with the single aim of fattening their own wallets. But there is one thing that both Gym Bros AND Gym Pros seem to agree on – To lose fat, you MUST do Cardio! Cardio is a wide-ranging term which encompasses any physical activity that requires oxygen for meeting the energy requirements of the athlete and raises his/her heartbeat. However, most people understand cardio as simply some form of cardiovascular or aerobic exercise such as running, cycling or even dancing. The connection between fat loss and cardio is so strong and runs so deep in most peoples’ minds that the largest and busiest area in most gyms is the cardio section which is usually choc-a-bloc filled with treadmills, elliptical trainers and stationary bicycles.

So, does cardio really help in fat loss? If yes, then what kind of cardio is best? HIIT vs LISS HIIT (High Intensity Interval Training) and LISS (Low Intensity Steady State) are the two most popular forms of cardio done by gym rats the world over. They are also the subject matters of one of the most contentious debates ever to have raged, with just about everyone giving their two pence about which of them is better for fat loss. The saga of HIIT and LISS is akin to the fable of The Hare & The Tortoise. But while everyone knows how that story ends, the debate surrounding these two forms of cardio has made it difficult to pick a clear winner. In this article, let’s examine what the science says about the pros and cons of both HIIT and LISS. Hopefully by the end of the article, you will find answers to almost all your questions. High Intensity Interval Training (HIIT) As the name suggests, HIIT involves alternating between high intensity and low intensity exercise activity in rapid succession. Each activity is performed at one level of intensity for a certain period of time and then switched over to the other level of intensity without taking any rest/break in between. This is usually done till the athlete is completely exhausted, though most HIIT sessions last for 30 minutes. A typical HIIT session on the treadmill could look something like this: • Warm-up: Steady State Cardio on the treadmill – 5 minutes • Run with maximum intensity – 20 seconds • Reduce the speed to low/moderate intensity – 60 seconds • Repeat till you are exhausted There are no fixed time intervals for HIIT; different people follow different time intervals switching between high-intensity and low-intensity training. The number of repetitions/cycles, time period, intensity, etc. would depends on the exercise that you choose and your individual fitness level. As HIIT is mostly anaerobic, the major source of fuel for HIIT is glycogen (carbohydrates) rather than fat. What’s unique about HIIT is that just like weight training, it produces a calorie after-burn effect or EPOC (Exercise Post Oxygen Consumption). The bad news is that EPOC has a negligible impact on fat loss. Research shows that EPOC barely burns 80 calories in 7 hours, even after 80 minutes of weight training. What matters more are the calories burned during the course of the workout/ exercise. Pros: • Time-efficient as compared to LISS May help improve appetite for people who have a bad appetite • Can be customized to suit individual needs • May effectively increase the aerobic capacity i.e., the oxygen utilization by the body • May help in increasing the lactate threshold Cons: • Highly fatiguing especially when combined with weight training. Could negatively impact proper recovery • Depends on the fitness levels of the individual, thus making it beyond the reach of unfit individuals • As glycogen is the major source of fuel for HIIT, performing HIIT at the end of the workout is really difficult as glycogen levels come down at the end of the workout Low Intensity Steady State Cardio (LISS) LISS or Low Intensity Steady State cardio, as the name suggests is a state of cardio where you perform the entire activity at low intensity for a certain period of time. The major source of fuel for LISS is fat. Typical examples of LISS include brisk walks, steady cycling for 30 minutes, etc. Pros: • LISS is less fatiguing than HIIT • As the major source of fuel for LISS is fat, it can be done at the end of the workout even with low glycogen levels • Almost everyone will be able to perform LISS as it is just like our daily activity. Cons that LISS have: • Time-consuming, as it takes longer to burn the same amount of calories as HIIT • Fewer aerobic benefits as compared to HIIT • Can becoming boring or monotonous And The Winner is... It depends. HIIT is not everyone’s cup of tea while LISS may not always help. As it turns out, there are enough reasons to do either type of cardio and equally persuasive reasons to avoid them. It’s difficult to make a blanket statement about which is better or worse. If you do want to incorporate cardio into your workout program, here are the suggested ways to do so: HIIT • Restrict HIIT to two sessions per week • Avoid performing HIIT post workout: The major fuel source for HIIT is glycogen which gets low by the end of the workout, hence fatigue may increase. LISS • LISS can be performed post weight training to burn some additional calories as the major fuel for LISS is fat and not glycogen • To keep LISS interesting, you can just go for a brisk walk outdoors. When energy expenditure is matched, HIIT and LISS produce similar results so the choice of cardio would ultimately depend on your personal preference & ability. The indisputable fact is that where it comes to fat loss, priority should always be given to weight training. HIIT or LISS should not form the core of your workout program. Fat loss takes place when you can create and sustain a caloric deficit and that’s really where HIIT and LISS can help.

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