The Truth About Cardio For Weight Loss

by DeanMcKillop 1430 views Weight Loss

The Truth About Cardio For Weight Loss

You DO NOT need to do cardio to burn fat! There I said it… the question you need to ask yourself now, is if you are going to just label me crazy and stop reading or continue through this short article and make your mind up for yourself?

Walk with me…

Cardio can simply be referred to as any exercise of an aerobic nature, whereby oxygen is required to be sent to the muscle during sub maximal intensity sustainable exercise.

However this does not account for high intensity interval training (HIIT), which can be done without the presence of oxygen. So for the purpose of this article we will be referring to cardio as any form of exercise that raises your heart rate that is not specific weight training.


Now if you’ve had the chance to read my article on the The 4 Key Steps to Fat Loss you will already know that the primary factor that determines fat loss is the energy balance equation and what macronutrient split the person is following. In short, if we eat fewer calories than we burn we lose weight and if those calories come from the correct macronutrients we enhance the likelihood of that weight loss coming from stored fat and not muscle.

That last line right there is the most important one. In a fat loss phase we want to:

Minimise muscle loss

Maximise fat loss


The moment we start losing muscle is the moment we reduce our ability to burn more fat. We reduce our metabolic capacity and performance will suffer negatively to the point where it will further enhance the negative adaptations of dieting. In essence, if you don’t maximise muscle retention, you can’t maximise fat loss.

So what does aerobic cardio do for us?
  • Improves cardio respiratory health
  • Is low risk (for injury) calorie burn compared to weights or HIIT
  • May lower cardiovascular disease risk

As you can see the benefits of traditional aerobic cardio are predominantly for health markers. If we were to look at HIIT, we will see the same positive benefits low intensity steady state (LISS) cardio has, however, research also suggests that HIIT has a slower adaptation phase whereby the calories burned for the amount of work done remains more constant, as opposed to LISS where the body adapts and burns less calories per minute to achieve the same amount of work over time.  It has also been shown to achieve the same benefits with significantly less volume (1).

For this reason, should you choose to use cardio in your exercise regime, HIIT will generally provided better benefits provided you can complete that style of exercise in the way it needs to be done.

Now lets look at weight training and its benefits:
  • Improves cardiorespiratory health
  • Increases muscle growth/retention
  • Improves blood glucose regulation
  • Improves metabolic health (direct and indirect)
  • Reduces the risk for metabolic X syndrome (pre-diabetes)
  • Improves hormonal profile


Essentially weight training does all the same positive things cardio does but PLENTY more positives with essentially no added negative metabolic adaptations. Weight training is the king of body re-composition, meaning it can illicit both a fat burning response as well as a muscle growth response (2), whereas cardio can only burn energy WITHOUT a positive muscle growth response.

Furthermore doing extended periods of LISS during a caloric deficit shows indications for enhanced metabolic maladaptation. Which basically means the more cardio you do while in a calorie deficit the harder it becomes to actually burn fat due to a negative hormonal response when the cardio is of long duration and low intensity.

Final Notes

Cardio is not bad and nor is it great, it is merely just another tool in the tool shed that you can use to achieve a particular outcome. While it may be indicated that LISS burns more fat as fuel during exercise when compared to weight training or HITT, it burns less fat thereafter in the post exercise phase. Regardless of both of these factors though, fat burning and the amount of fat you lose over time is more directly related to the net loss of fat due to calorie restriction as opposed to how much you burn in a single bout of exercise.

It’s not about what you burn in training, but instead what you burn throughout an entire day, week or month.  

Can you use cardio as a tool to burn more calories in an effort to prevent a further reduction of calorie intake? Absolutely you can, however it is by no means a necessity and should arguably only be used as a supportive exercise modality not a dominant one.

Focus on weight training and performance progression in the gym to ensure the most positive metabolic environment is maintained through maximal muscle retention and if you are unable to either increase the intensity, volume or frequency of your weight training, then use cardio as a tool to burn more calories.

Above all, training must be enjoyable!

So if you dislike cardio, find other means to burn energy. Similarly if you enjoy cardio, add it in to your routine. Just don’t rely on it as the dominant exercise modality.

Cardio is a tool, not a necessity! 

Article updated by Paula Vargas Duran for Fit Talk.

Gibala, Martin J. and Sean L. McGee. "Metabolic Adaptations To Short-Term High-Intensity Interval Training". Exercise and Sport Sciences Reviews 36.2 (2008): 58-63. Web.

Geleibter, A. “Effects of strength or aerobic training on body composition, resting metabolic rate, and peak oxygen consumption in obese dieting subjects”. American Society for Clinical Nutrition 66 (1997): 557-563. Web.



Exercise Scientist

I completed my Exercise Science Degree at the University of QLD and have worked in the fitness industry for over 8 years, including a short stint at the Brisbane Broncos in 2010 as a student. I also hold my Level 2 Strength and Conditioning Coach accreditation (ASCA) and have competed in 1 bodybuilding season, placing 2nd at the IFBB u85kg Nationals.

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