Unsure if high intensity interval training (HIIT) or low intensity steady state training (LISS) is better for fat loss? I will explain the science behind fat loss and help answer this question.
The thought of doing cardio usually invokes strong feelings for most people. In my experience people either love doing cardio or hate it. There are very few people that are indifferent on the subject. Some love the feeling they get from hopping onto a treadmill and working up a good sweat, while others would rather drive over their own foot just to have an excuse to skip their cardio for the day. Whether you love it or hate it, when it’s time to start getting lean and toned cardio poses a lot of questions for a lot of people.
Questions about duration, frequency, intensity are common.
Cardio is necessary to get very toned, but you have to get it right. Too much and you can risk sacrificing muscle, too little and you’ll find you won’t get lean enough.
If you have a suitably good diet and you get your cardio right, you can be sure you will become lean and have muscular definition.
The first thing that must be established is how many days per week cardio sessions should be performed. This is often where people’s love or hatred for cardio comes into play. Those that love cardio will tend to start too many sessions per week. This is not a good thing because the human body is highly adaptive. Your body will adjust to this level of cardio faster than you would like resulting in a weight loss plateau.
Once this happens your only choice is to cut calories or increase cardio. Those that take that approach will find themselves only a few weeks into their diet doing two cardio sessions per day every day just to keep fat loss moving.
This will lead to overtraining and muscle tissue breakdown.
Those that hate cardio will tend to try and ease themselves into their workout by starting really low and trying to increase it slowly. This isn’t necessarily a bad idea, but when dieting and trying to get results quickly, you must use your time wisely. In my experience if you start with too few sessions per week it will take you a very long time to get results.
The best approach is a more moderate one. The amount of cardio that you should start with is highly dependent on your body type so I can’t give you exact requirements on frequency, duration and intensity. Just know that starting with a more moderate approach and moving upwards from there will ensure the best results.
THE GREAT DEBATE
The number one question people have about cardio is “what type of cardio is best for fat loss?”
There are those that say low intensity cardio performed for longer periods of time is better for fat loss, while others claim short duration, high intensity cardio sessions will give better results. This is the part which tends to confuse people the most. Advocates on both sides of the argument are usually pretty passionate about their beliefs. To know which style of cardio to perform, it helps to know how each one helps burn fat.
LOW INTENSITY, LONG DURATION CARDIO
Generally this type of cardio is performed at a constant pace for 60 minutes or more. It is often referred to as Low Intensity Steady State Cardio (LISS) or Low Intensity Continuous Training (LICT).
The main argument for this type of cardio is that, of the calories burned, most of it comes from fat.
During any type of exercise, the level of intensity is very important. It is well known that the lower the intensity of any exercise, the greater the percentage of energy derived from fat oxidation.
As the intensity of exercise increases more of the calories being burned come from muscle glycogen and muscle tissue. This is why advocates of LISS usually prefer to walk on a treadmill or cross trainer for long periods of time.
They feel that by doing this they are burning more fat and less muscle.
The only problem is that during the entire time any type of cardio is being performed your body is in a catabolic state and it is breaking down muscle tissue for energy. Switching from a low intensity pace to a more moderate pace and lowering the duration a little may be a better option.
Moderate intensity steady state cardio has proven to lead to the greatest amount of fat oxidation. Research has shown that fat oxidation is highest when training is about 65% Vo2 Max. At this intensity level, not only is the greatest amount of fat being burned, but this rate of exercise can be continued for somewhat longer durations as well.
For individuals with a low body fat percentage (12% or less for men, 20% or less for women), at this point muscle tissue breakdown becomes more likely. Limiting the amount of time that your body is catabolic is vital if you wish to hold onto muscle. So for maximum fat loss and muscle retention, moderate intensity cardio for a moderate duration is the best option.
HIGH INTENSITY, SHORT DURATION CARDIO
High intensity, short duration cardio has become popular in recent years. For example ‘Insanity” which is very hyped about recently is nothing innovative or groundbreaking. It is essentially high intensity, short duration cardio.
The most effective high intensity cardio has been proven to be High Intensity Interval Training (HIIT).
HIIT allows for very high intensities to be used alternated with short periods of recuperation. Many people shy away from high intensity cardio, claiming that nearly all of the calories that are expended come from stored muscle glycogen and not from fatty acids.
This is very true, but those people are forgetting one very important thing. Fat loss occurs through a process called lypolysis.
Lypolysis occurs during periods when energy expenditure exceeds caloric intake. The most important thing during cardio is burning enough calories to create a deficit. This can be accomplished much quicker with high intensities.
Even though stored carbohydrates in the form of muscle glycogen are the primary fuel source at higher intensities, fat loss will be greater with the use of HIIT. Studies show a greater loss of subcutaneous fat (visible fat on your body) with HIIT compared to those that performed standard LISS endurance training. The reason for this is because post-exercise lipid utilisation is greatly enhanced with HIIT. This means that even after activity has ended your body will keep burning fat. This is referred to as ‘after-burn’. So not only can you burn calories during training, but your metabolism will also get a boost.
Another concern people have about HIIT is that at higher intensities a greater amount of amino acids are broken down and used as energy. This is true, but many people will be surprised to find out that if HIIT sessions are kept short (4-30 mins) then they can actually help retain and even build muscle. That’s right, cardio can help you build muscle. And yes it is possible to get a good workout in 4 minutes and anyone who tells you otherwise isn’t giving you the right workout. Any type of intense exercise whether that be cardio or resistance/weight training will cause your body to release growth hormone (GH).
The growth hormone response to aerobic activity is determined by the % of Vo2 max. Therefore, the harder you push yourself, the higher growth hormone levels will go. Some of you may be thinking, “so what? If I am supposed to keep my sessions short I will only get 4-30 minutes of higher growth hormone levels.” The good news is that, not only will these brief, high intensity sessions cause an immediate GH increase, but GH levels can keep rising even after training.
GH is not the only hormone affected by HIIT. Testosterone levels can also be optimised through strategic use of HIIT.
During and after high intensity aerobic exercise, testosterone levels become elevated and remain elevated for a couple of hours into recovery. This is only true with short durations though. Prolonged high intensity exercise results in an initial increase in testosterone followed by a decrease to below baseline levels.
This is another reason why it is important to keep sessions as intense as possible and short.
There is one problem with HIIT though; there are limits as to how many sessions can be performed before it becomes counterproductive. If HIIT is performed too often, then baseline testosterone levels will decrease and will lead to an increase in amino acid breakdown. This is why it is best to keep these sessions to only a few per week. In other words quality over quantity is key.
Another limitation of HIIT is who can actually do it. Due to the intense nature of this kind of training, it requires you to have a certain level of fitness to be physically and psychologically able to do it. HIIT is not recommended for beginners who have not done cardio exercise before or people that have had long periods without exercise. Besides the fact elevating heart-rate levels beyond 80% of your maximum HR would be dangerous to someone who has not experienced anywhere close to that intensity before, this level of intensity required is unlikely to be maintained throughout the duration of the session thus making it in-effective. Certainly beginners should achieve a baseline fitness level through LISS cardio training for a good 1-2 months before attempting HIIT.
Anabolic hormones such as testosterone and GH are the key to building and keeping muscle. HIIT can produce sharp increases in both of these hormones which will go a long way to help retain muscle when calories are low. HIIT can also increase fat burning by boosting the metabolism. This is why HIIT cardio is a great choice for getting lean while maintaining or even trying to gain muscle.
So which type of cardio should you use to help you get to the next level of conditioning?
The answer is….both.
HIIT cardio can only be performed a few times a week for it to be effective, but not many people can drop their body fat low enough doing only a few cardio sessions a week. LISS sessions will need to be added to make sure enough cardio is being performed every week. It is possible to incorporate HIIT as well as LISS with resistance/weights sessions, in fact depending on how you do your weight training you can achieve the same HIIT & LISS training benefits.
This is not the only reason to use both types of cardio. Both approaches shed fat effectively, but through different pathways. HIIT will increase lypolysis primarily by speeding up the metabolic rate, whereas LISS will burn more fat and calories during the actual workout.
As I said earlier, I can’t give an exact number of sessions you need to perform each week since the differences in individual metabolisms can vary greatly. A good starting point would be to do 2-3 HIIT sessions per week and add in some LISS sessions around this on your ‘rest’ days.
THE THING WITH HIIT IS THAT IT NEEDS TO BE DONE PROPERLY – AT A HIGH ENOUGH INTENSITY IN ORDER TO GET THE FULL BENEFIT AND REALLY UNLEASH THAT ALL IMPORTANT ‘AFTER BURN’ EFFECT THAT WILL CAUSE YOU TO BURN CALORIES UP TO 12 HOURS AFTER YOUR WORKOUT.
I’LL BE HONEST, WHEN I SEE MOST PEOPLE DOING ‘HIIT’ IT’S MORE LIKE MEDIOCRE OR MILD INTENSITY, AND TO BE FAIR IT IS NOT EASY TO PUSH YOURSELF AS HARD AS YOU NEED TO WHEN YOU’RE ON YOUR OWN, PARTICULARLY IF YOU’RE INEXPERIENCED.
IF YOU’VE GOT SOMEONE ENCOURAGING AND PUSHING YOU ON WHO KNOWS WHAT YOU’RE GOING THROUGH AND KNOWS EXACTLY WHAT YOU NEED TO DO THEN YOU WILL GIVE IT MORE EFFORT.
THAT’S EXACTLY WHAT MY CLIENTS EXPERIENCE WHEN THEY SIGN UP WITH ME. MOST WILL TELL YOU THAT THEY GET MUCH MORE OUT OF A TRAINING SESSION WITH ME THAN THEY DID ON THEIR OWN WITH ME ENCOURAGING AND PUSHING THEM ON AND ALSO BECAUSE THE SESSIONS I SET ARE COMPLETELY TAILORED TO THEIR GOALS AND ABILITY, AND FIT IN WITH THEIR SCHEDULE.
NOT ONLY THAT BUT I COACH THEM IN HOW THEY CAN MOTIVATE AND APPLY THE SAME EFFORT THEY DO IN THEIR PT SESSIONS WITH THEIR SOLO TRAINING SO IT’S ALMOST AS IF I WAS THERE WITH THEM!
If you think you’re ready to start losing weight and take your health and fitness to the next level then please get in touch now to be one of my clients. One thing you should know though, I only work with people that are committed and really ready to make positive changes. You don’t need to be an athlete of do anything impressive, but you do need to give 100% effort.