Q+A: Can a heart rate monitor help me lose weight?

Q Having passed 40, I’m finding it difficult to shed unwanted pounds. I’ve picked up my training but nothing is moving! I’ve just purchased a heart rate monitor, with the intention of zone-targeting for weight loss. What is the best way to burn fat? Do I go long and slow, or should I keep up the pace and go for the ‘burn’?

A The key to fat-burning is to realise there is not an instant ‘switch’ from fat-burning ‘on’ to fat-burning ‘off’. Plus or minus a small variation, you will burn the same number of calories per mile of running (assuming the same terrain) whatever the pace. It’s just a case of whether carbohydrate is taking up a little (40 per cent) or a lot (80 per cent) of the calories burned.

Ultimately, it’s the overall number of calories you burn that determines how much weight you lose, but staying below the excessive carbohydrate-burning zone helps use more fat as immediate fuel. If you were to ‘go for the burn’, you’d experience a build-up of lactic acid – the result of very high sugar-burning with the use of very little fat for fuel. Hard runs are also a big psychological effort.

So, although some faster running is good for our ego, economy and pace judgement, to lose the lard it’s better to put your energy into more miles at a slower pace, rather than fewer at a faster tempo. A good rule of thumb devised in the USA is to train up to a heart rate calculated by taking your age from 180. So at 40 you train up to a HR of 140.

If you have to walk occasionally to keep your HR down, then walk – your aerobic system is still being built up, and going too high will just result in lactic acid flooding your muscles.

There is no short cut to weight loss: it’s consistency, a slight reduction in calorie intake and (ideally) some resistance training to complement your running. Fat is slow on and slow off – you can’t run hard to lose it faster. You just end up overloading muscles, joints and your brain.

–Joe Beer, sports scientist and triathlon coach