Cardio: HIIT or LISS for Fat Loss?

“Change happens through movement and movement heals.” — Joseph Pilates
When you decide to move, you finally defeat chronic disease. When you dedicate your life in becoming fit, you turn your life habits into a healthy lifestyle.
What the best training style for fat loss? I get this question a lot in and outside the gym. First of all, I’d like to say that any form of exercise, whether you’re doing bodybuilding, CrossFit, high intensity interval training or low intensity steady state cardio, is good for you. When you decide to move, you finally defeat chronic disease. When you dedicate your life in becoming fit, you turn your life habits into a healthy lifestyle. But in speaking purely about fat loss, creating a caloric deficit in energy expenditure is inevitable. Science tells us that that when the calories we expend are more than what we consume, we utilize our stored energy reserves, a.k.a. “fat”, to function and survive.
We can’t go around science. A caloric deficit is needed for us to lose weight. But losing weight shouldn’t be the end all, be all of our fitness journey.
Now, does this mean fat loss is the end all be all, the ultimate goal we should strive for? Should we only do the type of exercise that will make us lose fat? In both cases, absolutely not. There’s more to fitness than pure fat loss and creating a caloric deficit isn’t a magic pill. But for this article, let us dive deeper into the science behind how we burn fat through different types exercises such as High Intensity Interval Training or HIIT and Low Intensity Steady State or LISS.
Join me as I explore the science behind HIIT and LISS!
HIIT: The Good and Bad
Today, there is much debate amongst fitness coaches and enthusiasts about HIIT and LISS. The arguments over which is better for fat loss and overall health are never-ending. The vast majority says HIIT is far more superior than LISS when it comes to fat loss and preserving muscle. There is a truth to this and let us see why.
The equipment or style matters not as much as how you are doing it. Whether you’re outside running or using free weights inside the gym, as long as you are moving at this pace, you are performing HIIT.
According to Ross Edgley, “High Intensity Interval Training or HIIT involves a frenetic pace for 20 to 90 seconds followed by a period of low-intensity training or complete rest that lasts or 20-120 seconds.” Basically, it’s a sprint, rest, sprint, repeat that you typically do for 10 to 20 minutes. The equipment or style matters not as much as how you are doing it. Whether you’re outside running or using free weights inside the gym, as long as you are moving at this pace, you are performing HIIT. I won’t get too much into the details, but to paint the big picture, we burn the most fat when doing HIIT. This is because of a phenomenon called “Excess Post Exercise Oxygen Consumption” or EPOC, which tell us that we are create a debt in oxygen inside our bodies. Our bodies then burn calories while repaying this debt even after exercise. Studies show that this “after burn” effect can last up to 48 hours after a HIIT session, which means you are still burning body fat two days after you train. Sounds really great! In fact, scientists from Laval University in Quebec Canada compared a 15-week HIIT program to a 20-week endurance training program. After taking muscle biopsies and body fat measurements, they discovered that the HIIT program was more effective at speeding up the body’s metabolism. This resulted in greater fat lost in lesser time.
“Most people have no idea how good their body is designed to feel.” — Kevin Trudeau
The “after burn” effect lasts up to 48 hours after performing HIIT, enabling your body to continuously burn fat and speed up metabolism.
Of course, as with anything really good, it comes with a price. We cannot sustain doing HIIT everyday. Our bodies will simply burn out because HIIT taxes the central nervous system and endocrine system. What this means is that our body’s internal circuitry can and will short-circuit when overloaded with stressful stimuli. Also, our hormonal system, which keeps our bodies in a state of balance, will have a hard time doing its job. A big chunk of our body’s total cholesterol, which is an important fatty acid for cell membrane health and sex hormone production, will be channeled to producing cortisol— a phenomenon called “cortisol steal”. According to Dr. Rangan Chatterjee, “Because it thinks you’re under attack, and in a state of crisis, your body prioritizes the generation of cortisol. It thinks you need to cope with the drama and just makes more and more of it. That upsets the finely tuned balance of hormones in your body.”
“For every substance, small doses stimulate, moderate doses inhibit, large doses kill.” — The Arndt-Schulz Rule
Switch up your training from time to time. Go outside for a run, attend a yoga class or do jump ropes.
Our bodies are all unique and so should our training methodologies be. We perceive and adapt to intensity differently. Running 400 meters under 3 minutes might be really intense for a 60 year old grandma, but it’s nothing more than a warm up for a competitive CrossFitter.
Paolo’s warm up is your grandma’s workout!
LISS: The Good and Bad
Low Intensity Steady State has gotten a bad rap over the last few decades. It’s been vilified to be muscle wasting and catabolic which ramp up our stress response. This is rightfully so, but only if you do LISS the wrong way. Contrary to popular belief, LISS can be a valuable tool in our fitness program, in losing fat and boosting our immune system. First of all, LISS, when done at 50-65% of your max heart rate for no more than 60 minutes, utilizes only fat for energy. Studies show that doing LISS without insulin, or when done on a fasted state, allows you to tap into your stored body fat as well. Secondly, studies also show that LISS boosts the immune system compared to HIIT which impairs it. Once the exercise climbs in intensity, however, the body will start using carbs and the nervous system goes into overdrive. Sustain this for too long, and our immune system will take a beating— a phenomenon called “Exercise-Induced Immunodeficiency.”
Intensity is good, but not always.
The more intense the workout, the harder it is for our immune system to cope up. Now, does this mean LISS is better than in HIIT in promoting health and burning more fat? The answer is no, and this is where it gets tricky.
Yes, we do use more fat in the midst of performing LISS compared to HIIT, but the total fat that is being burned is not necessarily a huge amount. According to Thomas DeLauer, “Oxygen combines with fat while performing LISS. While you burn more fat calories with LISS, overall you are burning less calories than HIIT.” This is because once you have finished doing your LISS session, you are also done burning fat. In HIIT, however, you continue to burn fat even up to two days after your session.
Understand how your body adapts to different training methods and stick with the one that works for you.
“As to methods, there may be a million and then some, but principles a few. The man who grasps principles can successfully select his own methods.” — Ralph Waldo Emerson
Do What Works for You
Both HIIT and LISS can be incorporated into your program for fat loss and overall health but the trick is knowing which one or, more importantly, how much of each is best suited for you. To do this, you will need to understand how your body adapts to exercises.
There are a thousand ways to skin a cat, but the one you can stay consistent with is the one you enjoy. Relax and enjoy the process!
Exercise, no matter how important and beneficial, is still a stressor. The higher the intensity, the more stress. As we know, the hormone cortisol is released during a stressful situation regardless whether we are giving a presentation, or during intense exercise. According to John Berardi, PhD, founder of Precision Nutrition, “Too much cortisol too often is a problem (i.e., with lots of high-intensity training). Eventually, we stop recovering. Cortisol keeps our blood sugar high and thus chronically high cortisol change where fat is deposited. An easy tip-off is fat on the upper back.” This is one of the greatest reasons for us to know the sweet spot of balancing and blending HIIT, LISS and even strength training.
Manila Throwdown 2018. After two days of competition, I placed 12th overall in my division. The months of preparation and hard work paid off.
Back in 2017, when I was preparing for a CrossFit competition, I was training intensely five to six days a week with heavy weightlifting, gymnastics, endurance work and a combination of all three. Although I followed a sound and tested program, my body was not able to catch up on recovery. I had many things going on— training clients the entire morning and evening and not getting enough sleep. Then, I would insert my training session in the afternoon, which would last for two to three hours. This took a toll not just on my immune system, but also on my blood glucose readings. I was constantly getting viral infections and the worse was when I was admitted in the hospital for three days. What shocked me the most is when I learned that my fasting blood glucose read 96.05mg/dL (100 is the upper limit and is considered pre-diabetic) despite eating relatively well.
Manila Throwdown Team Edition 2017. We wouldn’t have enjoyed the game day had we not prepared hard for it.
Here are some tips and tricks to know whether your training program is working for you and not against you:
  • Know how much stress you are already getting outside of your workout. If you are already chronically stressed from work, revolving your exercise program around HIIT may do you more harm than good. It will be harder for your body to recover and thus harder for you to lose that stubborn fat. Make sure your program is one that your body can recover from to ensure a consistent progress.
  • Be aware of the speed at which your body recovers. A good gauge of this is monitoring how you feel upon waking up first thing in the morning. If you feel sluggish and keep on hitting the snooze button, that might be a sign of chronic stress. A lower intensity exercise would be best for you that day to help you recover. Feeling good and jumpy, however, means that you are well-recovered and are ready for an intense training session that day.
  • Be aware of your own mood. Feeling constantly on the edge and anxious is a sign of stress. You might be overtraining or simply not able to recover from all the beating your body gets. It’s important not only to take care of your body, but also your mind and soul. Make sure you set aside a time of solitude and reflection to cultivate and nurture your inner world. No matter how well you recover, sleep or eat, if your inner world is turbulent, it can easily manifest as chronic fatigue.
  • Seek out professional advice. Working with a qualified fitness coach allows you to create a sustainable and specific workout program best suited for your lifestyle.
Don’t worry. I’m not gonna skin this one!
“Don’t be emotionally attached to a nutrition or training principle; as science progresses, so must we.” — Ross Edgley
Seeing the Bigger Picture
We all can benefit from HIIT and LISS but the art is in knowing when and how to use these training styles. At the end of the day, the important thing is not which one is better, but which one is working best for you. To do this, you need to be aware of your current lifestyle and how much extra stress from exercise you need. Next, you have to distinguish what you think you need versus what you actually need. Many guys think they need avoid cardio altogether because it will waste their muscles. They may not be aware that while they are strength training and doing HIIT, their body fat may be reaching obesity levels because of over fatigue. They are clueless about putting themselves at a greater risk for heart disease.
What you think you need and what you actually need may be two different things. At the end of the day, the important thing is not which one is better, but which one is working best for you.
It takes a certain level of honesty to be able to face ourselves in the mirror and admit what is best for us. Are we pursuing our own goals, or other people’s goals for us? My advice as a fitness coach is to always cultivate awareness. Know yourself and know how different exercises affect your body—this will point you towards fitness, health and wellness.
“Balance is the key to everything. What we do, say, think, eat, feel, they all require awareness, and through this awareness we can grow.” — Koi Fresco

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