HIIT vs Cardio for Fat Burning

Over the last few years high intensity interval training has become hugely popular due the effect know as EPOC (excess post exercise oxygen consumption). In essence all this means is increased calorie burning after the exercise has ended.

Traditional cardio went on the back burner and became less popular as a modality, except in the body building world. In recent times the debate between cardio and HIIT has come to the forefront again, with people debating the efficacy and efficiency of each and their role in fat loss specifically.

This can be incredibly confusing for those looking to lose weight or optimise weight loss. What’s the truth? What does the science say vs internet fitness gurus?

Fasting has also become immensely popular with 16:8, OMAD and all sort of other variations coming to the forefront of the weight loss world. Should HIIT or cardio be done fasted, as many people claim, to improve results?

HIIT vs Cardio — Which burns more fat

Fat Burning During Cardio

Fat burning in cardio vs high intensity training. Bear in mind high intensity work cannot be performed for as long as cardio and thus the calories per hour may be higher in HIITbut if it’s performed for 20 minutes it will look similar to an hour of cardio.

Fat Burning During HIIT

In other words, as exercise intensity climbs fat burning drops, as seen in cardio. Yet when the intensity is high fat burning increases post exercise, while it’s practically non-existent post training.

Oxygen debt created by HIIT which then is “repaid” once exercise has ended. https://journals.lww.com/acsm-healthfitness/Fulltext/2019/07000/EPOC__IS_IT_REAL__DOES_IT_MATTER_.6.aspx

24 Hour In

Long Term Results

Weight loss cannot happen without a calorie deficit and as such this is a pre-requisite for these things to have an impact on someone looking to lose weight. Assuming a calorie deficit has been achieved either via diet, exercise or both we can progress on to the long term findings.

One thing really stands out when looking at the long term impact and this is the maintenance of muscle tissue. Muscle tissue is one of the keys that keeps your calorie requirements higher and in a calorie deficit, if muscle isn’t stimulated appropriately, it can be broken down and used as a fuel source in addition to body fat.

HIIT does a much better job at maintaining muscle tissue than cardio does. This isn’t really surprising when you consider the intensity difference. Muscle that is required to work hard is regarded by the body as necessary and less likely to be broken down. This is one of the reasons marathon runners are thin. They body will adapt to its environment and the stressors it’s exposed to.

Lie in bed all day and you will lose a lot of muscle tissue, spend time stimulating the muscle and build/maintain it.

Fasted Or Fed

The same idea holds true for HIIT. With the rise of fasting modalities training in fasted state for fat loss has become more popular. But hold your horses, the science on this is extremely interesting. In reality, the body burns more fat post exercise when in a fed state. Yes, you read that right. When fed milk and glucose (sugar) pre exercise those performing the exercise burnt more fat over all post exercise than the fasted group.

This has a few important, often ignored, benefits. The first being that in HIIT and cardio are often performed for fat loss, so we will be in a calorie deficit. A calorie deficit also means recovery is slower. This is obviously down to the fact that we are consuming less energy. Someone at weight maintenance or in a calorie surplus can recover faster than someone in a deficit. Feeding pre exercise may not only result in increased fat burning but may also result in increased recovery, which we want to optimise during fat burning.

The next thing worth considering is performance. While losing weight performance can drop, especially when body starts getting low. Being fed pre exercise may increase exercise performance for some people as it allows for the replenishment of glycogen (the carbs stored in muscle). This is especially true for exercise at high intensities, as this is when glycogen will be used as fuel.

What does this mean for you?

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I have an avid interest in all things human body and as such help people lose weight. Other interests include language learning and the science behind longevity