Updated: Mar 12
As a personal trainer, I’ve had a ton of people ask me which form of exercise burns most fat. I often reply with the most truthful answer: It depends. The answer to this question depends on a few factors: your current fitness level, the exercises you are currently doing, your existing eating habits and your likelihood of actually doing the exercise.
There’s a lot more that goes into reducing fat mass than the form of exercise that you do. Nutrition and rest periods are just as important, but the exercise part of it is what we are focusing on today. The fat that you accumulate or lose is regulated by a balance between expenditure and intake. Exercise burns fat by increasing your body’s caloric expenditure.
There are three major ways that exercise increases caloric expenditure:
Increasing caloric expenditure during exercise: Calories are used to contract and extend muscle fibers. Your body uses more calories to walk around than it does to sit down. An exercise session increases caloric output and therefore increases the total amount of calories that you burn in a day. Exercise puts your body into a ‘fat burning zone’ where it burns more calories than usual.
Increased caloric expenditure while recovering from exercise: This ‘fat burning zone’, where more calories are used up than usual, continues after exercise because your body spends energy to recover from the exercise. It costs energy to pump blood faster, shuttle nutrients to muscle fibres and remove by-products like the lactic acid that gives you that burn feeling in your muscles.
Increased metabolism: Your body will slowly learn to adapt to exercise by increasing its metabolic rate. Your metabolic rate is the rate at which your body burns calories for energy. As your metabolism increases, your body will burn more calories naturally – even while you are not exercising or recovering from exercise.
The higher the intensity of the exercise, the more fat it will burn
Higher intensities burn more calories during and after exercise. They also stimulate the body into increasing metabolism faster. The higher the physical cost (or caloric cost) of exercise, the greater the caloric expenditure.
Muscle mass increases metabolism
There is a reason why muscle mass decreases over time, and that the muscle you build up from exercise decreases when it is not stimulated regularly - muscle costs a lot to maintain. If there is no need for this cost, the body reduces it to save on calories. For this reason, exercises that increases muscle size will increase daily calorie expenditure.
Is high intensity interval training the best form of exercise for losing weight?
Currently, HIIT (high intensity interval training) is all the rage right now. Almost everybody in the fitness world would tell you that high intensity training is the best form of exercise to lose weight. While interval training is the most efficient way to burn calories, it might not be the best way. High intensity interval training takes a lot out of you, and you need to be at the right fitness level to be able to do it consistently. Burn Fat Exercises that is too heavy on your body can increase cortisol levels, which can break down muscle fibres. This is called catabolism.
What’s the difference? Let’s use an analogy
Sally is 47 years old. She’s been a single working mom who has had to work long hours every day to give her children the best life possible. Because of her long hours of work, she hasn’t made time to exercise in over 20 years. She’s eaten whatever was the most convenient and her minimal spare time was spent on relaxing as much as possible before the next stretch of work and chores. This has led her to gain a lot of weight and her yo-yo diets throughout the years have never lasted longer than a month. Now that her kids are older and she has worked her way up to a good job with normal working hours, she has decided to start looking after her own personal health. Will interval training burn fat faster than other exercise forms? Absolutely. Is interval training the best form of exercise for Sally? Absolutely not.
Sally has not exercised in years. High intensity exercises will take too much of a toll on her body and it will start to break down before it can adapt to the new changes. If high intensity exercise is the first kind of exercise that she does in such a long time, her first impression of exercise will be that of exhaustive effort. Personal trainers that push their clients too hard during the first session often never see their clients for a second session. We all know how hard it is to break a first impression. Sally needs to learn to enjoy exercise. It needs to become her ‘me time’. The only way we will stick to a health routine is when we can develop a positive outlook towards it. Sally would be much better off starting with a form of exercise with a lower intensity to prepare her body and perspective for a pro-exercise lifestyle. Since her body has not had a lot of physical stimulus in the last few years, smaller efforts will lead to bigger initial results. These results, along with her increased physical capability, will motivate her to increase her exercise intensity over time.
HIIT (high intensity interval training) is the best form of exercise to burn fat as quickly as possible, but the form of exercise which will benefit you the most depends on how much you already exercise. For someone who is just starting out, I’d recommend a lighter intensity to start off with. As your fitness level increases, you can increase the intensity of your exercise regime to burn more fat per exercise session.
Mr. Saguren Redyrs is a personal trainer from South Africa who is passionate about helping others to live their best, healthiest life. He is the founder of the health and fitness website SA Spotters.