One of my favorite movies of all time is The Usual Suspects. In a legendary scene Kevin Spacey, as Keyser Soze tells Agent Kujan the greatest trick the devil ever pulled was convincing the world he did not exist. I can tell you that the greatest trick that the gym industry ever pulled was convincing the world that exercise has anything to do with weight loss.

Never mind that exercise isn’t a conceivable strategy for weight loss. The gym industry is banking on the fact that you will fail.

You just won’t go.

For a gym to be profitable it generally has to have a membership base ten times what it can fit inside the premises at any one time.

American gym chain Planet Fitness has on average 6500 members per gym. Most of their gyms can hold around 300 people. Planet Fitness can do this because they know that members won’t show up.

Why aren’t members showing up? They aren’t getting results.

One of the biggest misconceptions surrounding exercise is that it can rapidly transform your body. Gyms and personal trainers have long propagated this notion, and it been an amazingly effective marketing tool.

It’s sold millions of gym memberships and personal training packages. But these claims are best half-truths. Exercise is not enough on its own. Those who suggest that the overweight executive can solve their weight issues with a gym membership are ignoring what is by far the most crucial component of any weight loss plan: nutrition.

The research conducted by the American College of Sports Medicine, the peak body for scientific research in this field; show that 4 7 hours of aerobic exercise are needed to promote the loss of 5% of your body weight.

An old adage that was passed through the fitness industry many years ago interpreted this research into these numbers: to lose 1 pound of fat (0.45kg) you have to expend 3500 calories of energy.

That would mean a 100kg adult would have to run 35km at 10km/hour or 6mins per kilometer. Put that into a training week and it becomes 3 x 10km runs (in an hour) plus one shorter 5km effort.

It may sound doable for a week, but try this as a beginner and you are sure to break down. Even if you avoid injury your body is constantly finding ways to become more efficient. As you get fitter the number of calories you expend will get smaller and the distance or pace will also need to increase.

The fact is, unless you are an athlete, you just can’t consistently exert the level of energy required to change your body weight through exercise. It must be done through nutrition.

If you would like to read more about how deconditioned executives can turn into athletes you can download a free chapter sampler of my book here or on the website.