Whenever I start working with a new weight loss client one of the first questions I ask is "are you currently exercising?" The answer is dead certain to be "yes, I walk most days..."

Huh?

If walking was really the weight loss answer we've all been looking for, how is that everyone who uses it to manage their weight can't seem to, well, manage their weight?

A few years ago Oprah (God love the girl!) attributed the success of one of her many weight loss excursions to spending hours walking on the treadmill, and ever since then we've become a nation of walkers. Oh, and the fattest nation on the planet. Not that I'm suggesting that walking is the cause, it just definitely isn't the answer.

Let's have a look at the physiology so we can put this poor bugger out of its misery and bury it once and for all.

Walking is a very natural movement for us humans as it has a pendulous, rhythmic movement and it expends little energy (a light should have come on then, serial walkers...). It is so energy efficient that we only use a handful of calories, in my case around 2-3 calories a minute (I weigh 60 kgs and walk at around 4-5 kph.)

To burn more energy we need to walk so fast that we lose a lot of that rhythmic motion, which is commonly known as power walking, but believe me, you need to be putting plenty of ‘power' in ‘walking' for that to happen.

Now – if we start running this becomes a lot less energy efficient because you have to push yourself forwards with each stride. Now you will use around ten calories a minute.

So I'm figuring that you've only got a limited time to exercise each day. Maybe 45 minutes. If I walk for 45 minutes I'll burn around 90-130 calories. That's less than the average cup of coffee.

If I run for the same period of time I will burn around 450 calories. Check out www.brianmac.co.uk/excel/energyexp.xls for a handy energy expenditure calculator.

Now given that we all struggle to find time to exercise, I know which one I'd choose. Remember – weight loss and keeping fit is about huffing and puffing for maximum results, so keep the intensity UP.