Most government campaigns these days focus on telling people to get out of their chairs and exercise.  That isn’t necessarily a bad thing – staying active has numerous health benefits, but it has lead to some serious misconceptions about what people need to do to lose weight.

How many times have you seen people spend an hour killing themselves on the treadmill, only to go to Starbucks and have a large coffee and a cookie afterwards.  In their head, they did a 5k run, so they deserve the treat.

Unfortunately, it’s not as simple as “exercise to lose weight“.  Exercise can help, but it isn’t a magic solution.  A Starbucks Venti Chai Latte with low fat milk contains 332 calories, and a chocolate chip cookie from the same store has about 430 calories in it.  That’s 763 calories in one after-exercise snack.

Let’s assume you’re a 150lb man, and you do your 5k run in 35 minutes – a decent pace for the average person.  You’d burn around 357 calories for your efforts, just slightly more than the calories in the drink, but your 5K run hasn’t “paid for” the cookie.

Calories In VS Calories Out

The equation for weight loss is quite simple.  If you burn more calories than you consume in a day, you’ll lose weight.  If you eat more calories than you use, you’ll gain weight.  The amount of calories your body burns in a day is known as your maintenance calories – the number of calories you would have to eat to stay at the weight you are.

If you’re trying to lose weight, a good goal is to consume between 250-500 calories fewer per day than your maintenance level.  That would amount to between 2 and 4lbs of weight loss per month.  Slow, steady, and sustainable.

How Does Exercise Fit In?

Exercise can help with that goal because exercise uses calories.  Let’s say that your maintenance calorie allowance on an average day, with no exercise at all, was 2,500 calories.  You’ve decided to aim for 4lbs of weight loss per month, which means you need to be 500 calories under.  2,000 calories might feel like a pretty strict allowance when you first go on a diet.

By doing that 5K run, you’ve increased the number of calories that you burn that day.  If you’re counting calories, you’ve just bought yourself an extra 357 calories to play with.  Whether you spend those calories on a beer, a couple of chocolate biscuits, or an extra serving of chicken and veggies is up to you – but for many people, that extra treat saves their sanity.

It’s the Math That Matters

Exercise is important, and does offer other health benefits, but exercise alone won’t make sure those extra pounds come off.  If you’re eating junk day in, day out, then no matter how hard you train in the gym, your waistline won’t go in the direction you want it to.  The only way you can guarantee weight loss is if you get your diet under control.

Written by Amy Fowler on behalf of The Poppy Run, who organise 5k runs in aid of The Poppy Appeal.