Weight Training Or Cardio?

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There is so much conflicting information. For many years women’s magazines were full of articles telling us to do lots of cardio to get the body composition we have always wanted.

But is this actually true? Have you been doing many cardio classes for months and not noticed the changes you hoped to see? Should you be doing something differently?

As ever in the world of health and fitness, nothing is ever quite as straightforward as we may like. The reasons for exercising should really be multiple. Of course many of us do it to “lose weight”, but the health benefits are also an integral and vital part of the picture.

And do we want to just “lose weight”, or is it a case that we want to lose fat? Would you be happy weighing the same, but being a different shape or weighing the same and feeling your clothes fitting a little differently?

The two main types of exercise are aerobic and anaerobic. Anaerobic exercise relies on using energy stored within the muscles, whereas aerobic exercise is dependent on oxygen gained from breathing.

And ideally, you need both. But why? And how is that going to help me with my goals?

OK….aerobic exercise (often called “cardio”), burns lots of calories. Especially for the duration of the exercise. If I run a mile I burn around 120 calories. Your calorie burn depends on your mass, gender, pace, heart rate etc etc, it wont be the same for everyone. A fitness class like my HIIT of half an hour burns nearly 300 calories on average. And this can really help when you are trying to lose weight, because if you use more calories than you take in as food and drink, then weight loss happens.


…with lots of cardio, some of the weight loss will come not from fat but from muscle. Your body uses up all available fuel sources to get through the exercise class including a little bit of muscle. SO you may burn lots of calories but they won’t all be from fat.

This is why anaerobic exercise (which includes weight training amongst others) is also important in your bid for fat loss. Muscle uses up calories whilst you rest (not many but some). The more muscle you have, therefore, the more calories you burn whilst you sit at your desk, in the car, etc.

This is why, if you only do cardio (and remember how that uses up some muscle? Well this is where that starts to matter), you may end up not losing the fat you are hoping to…..because you have LESS muscle, and so although you’ve burned all those calories doing a class, because some of those calories came from muscle, you burn LESS after you’ve finished training because you have less muscle mass to burn calories for the rest of the week.

Weight training helps to preserve and grow your muscle mass. This is important in burning body fat. It’s also important in keeping your bines and joints strong as you get older, and in helping with balance and mobility.

Studies have shown that although your cardio burns more calories during the exercise than weight training does, weight training keeps your metabolic rate raised for longer afterwards. High Intensity Intervals keep your metabolism raised for longer than slower steady state cardio does, but if you try and incorporate all three types of training into your weekly exercise schedule you will maximise your fat loss results.

If you need any help with planning your exercise schedule or calculating your calorie needs, contact me today.

For how much exercise you should aim for, see my previous blog post “how much exercise do I need

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