Why the so called “fat burning zone” doesn’t work

Training at low intensities – up to 55% of max heart rate – is considered to be training in the fat burning zone. Great! So a higher proportion of calories will be burned from fat supplies rather than carbohydrate supplies. Great!

So, what’s the problem?

Well it’s partly down to the simple equation of calories in versus calories out. A 30-minute cardio session at this intensity will burn 200-300 calories. 1 bottle of Lucozade will replace that!

Also, a study at the University of Colorado School of Medicine in Denver shows that there is no “after-burn” effect from this level of work out. The after-burn is based on the idea that after exercise your metabolism is raised so you continue to burn calories for a while after you’ve stopped. Bonus! However, it is generally believed that to elicit this effect you need to train at high intensities. In fact, low intensity exercise decreases metabolism! The study at the University of Colorado School of Medicine in Denver shows this as well as a study at the University of Vermont. This is probably largely due to a survival mechanism to conserve calorie expenditure. Worse news still, in terms of weight loss is that the more you calorie-restrict your diet, the lower your resting metabolic rate!

So what to take from this? Well, a study published on The British Journal of Sports Medicine website shows that other health benefits of exercise should really be acknowledged more. These include lower blood pressure, higher aerobic capacity and a quicker response to exercise, meaning improved health and a better ability to run for the bus! Other health benefits include mood elevation. After all, the main reason we do exercise is ultimately to feel better, right?

What else? To lose weight you need to eat sensibly and train hard.

Categories: Blog


  1. Elspeth says:

    In addition to the above, also good to note that cardio alone doesn’t build much in the way of muscle mass. This is why resistance training is beneficial for weight loss – the more muscle we have, the faster our metabolic rate, the more calories we burn – not just while we are working hard at the gym but throughout the entire day.

  2. admin says:

    yes, elspeth, definitely 🙂


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