Posted by: Cheryl | 2007/12/01

heart rate 2 optimise weight loss in gym

Hello there!
I am a 46 yr female. My weight is 90kg. I am 154cm tall.
I am following a reduced eating plan.
I have recently started working out at the gym about 5 times a week for half an hour:-
Threadmill 10 minutes, followed by 3 rounds of circuit.I finish off with 10 minutes of cycling. Inbetween the circuits, i cycle or use the "health walker" for 2 minutes to keep my heart rate high. My heart rate ranges from 135 - 155 whilst exercising.
Since i want to lose weight and not really build muscle,
1) Is the above fine or should i adjust anything?
2) What should my heart rate be for optimal weight loss?

Many thanks

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Our expert says:
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Hi Cheryl

There is a lot of confusion and misconception about this one. Ever since people noticed that heart rate goes up as intensity goes up, they have used it to gauge exercise intensity. Then, when it was noticed that the fuel that is used also depends on the exercise intensity, it was thought that heart rate monitoring was a good way to train at just the right zone to burn fat. In theory, this is true, but there is more to it than this. What happens is that at low exercise intensities (less than 60% of maximum), the main source of fuel used by the body is fat. As exercise intensity increases above 65 to 70%, progressively more and more of the energy that is produced comes from the carbohydrate stores, meaning that fat contributes a smaller overall percentage of the total energy use. However, and many people forget this, the overall energy use also increases, so that, even though fat might be contributing less as a percentage of the energy, it is still being used in larger quantities. That means that the total amount of fat being burned per minute might actually be higher at higher intensities, which is what you want. So, many people make the mistake of trying to go at a low intensity, to burn fat, which means that they are probably using more fat than carbohydrate, but the overall energy used is so low that the results are barely noticeable.

SO, basically, the body does not have certain ‘zones’ at which it uses just fat and then just carbohydrates – there is no on-off switch, but a gradual change from fat to carbohydrates, which means that you have to find the exact intensity to burn more fat in total, not more fat as a percentage, if you follow my logic. Also, at slightly higher exercise intensities, the total energy that is being used is greater, which means that the total amount of fat that is being used is also greater – so, to answer the question, I’m more in favour of higher intensity training to burn fat. However, a word of caution, this does not mean going out and training hard all the time. You have to find the right balance. Your goal should be to use the greatest total amounts of fat, and this means that the duration of the training must also be long enough to burn more fat. So, it’s not only the intensity, but also the duration that is vital. That’s why you can’t just go out and train at 90% of maximum – you would tire very quickly, meaning that your total fat and energy use would be relatively low.

Therefore, my advice would be to aim for an intensity between 70 and 80% of maximum. In your case, anything between 150 and 175 bpm would probably be about right – the main thing is to be able to finish a session of 45 minutes or so of training feeling like your breathing is elevated, that you’ve had a hard session, but that you are not completely exhausted. The other piece of advice is that you could also exercise at a low intensity (60 to 70%), with short periods of high intensity in between. So, say you are cycling for 45 minutes, every 9 or 10 minutes, you could pick up the intensity for one minute. This type of training is very good for fitness, performance and weight loss.

Otherwise, training sounds good. Just give it time and keep it up! As you get fitter, increase the time spent in the gym, especially on the cardio equipment. I think it's important to aim for at least 30 minutes of cardio, but you'll get there. Just focus on fitness for now, and let the rest happen!

Good luck


The information provided does not constitute a diagnosis of your condition. You should consult a medical practitioner or other appropriate health care professional for a physical exmanication, diagnosis and formal advice. Health24 and the expert accept no responsibility or liability for any damage or personal harm you may suffer resulting from making use of this content.

Our users say:
Posted by: Hendrikus | 2007/12/05


No the % does not change the fitter you become, the reason for this is that your Max heart rate stay the same, what will happen is it will take you longer to get to your Max heart rate. Do yourself a favour and buy a heartrate monitor, set it to % and stay below 65% for optimal weight loss, as your body burns fats at this level. Many group trainers make a commen mistake to push the people in their clases to hard, thus they dont burn fat.

Reply to Hendrikus
Posted by: cheryl | 2007/12/04

Many thanks for your great advice.
U say 150 - 175bpm is 70 to 80% of max.Is this for my age & Is there a scale to calculate %s?
As i get fitter does this % change and do i have to make adjustments?

Reply to cheryl

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