The average dieter makes four or five attempts each year.

The average dieter makes four or five attempts each year. Photo: Getty

"The definition of insanity" said Albert Einstein, "is doing the same thing over and over again, but expecting different results".

At least that's what the internet told me. So it must be true. I reckon Einstein hit upon this slice of wisdom when he was on the rebound from another disastrous yo-yo diet.

If he were alive today, perhaps Einstein could explain why seemingly sane and rational people continue to diet, despite overwhelming evidence — and years of personal experiences — that shows that diets don't lead to long-term weight loss and in many cases actually cause weight gain.

For the record, when I say "diet" I'm not taking about healthy eating. I'm referring specifically to calorie-restrictive, hunger-inducing deprivation. In other words, "diet" in the sense that most people use the word.

And I know that your great aunt or the guy from work lost weight and managed to keep it off. But these people are the exceptions who prove the rule. And yes, some people, probably most, can go on a diet and shed some kilos. But typically this weight loss is temporary.

If people could lose weight and keep it off long-term then the diet industry wouldn't be worth $60 billion a year. Weight Watchers alone has annual revenue of $1.75 billion, and one of its former managers has even admitted how unsuccessful the company is at helping people maintain their weight loss.

If diets worked, there wouldn't even be a diet industry — people would just do it once and be done with it. Instead, the average dieter makes four or five attempts each year.

Why, then, do we continue to believe that the equation: dieting = weight loss is a Universal Truth, as certain and undisputed as the law of gravity?

One reason is because no matter how frustrating and soul-destroying dieting can be, it gives us hope. Dieting is hard, but it's not nearly as hard as accepting ourselves, and our lives, as we are.

We're fooled into believing that weight loss is a path to redemption, love and happiness. And there is something intoxicating in the belief that we are just one diet away from changing our bodies, and therefore our lives.

An extreme example of this way of thinking can be found in Jaycee Dugard's memoir A Stolen Life.

Jaycee Dugard was 11 when she was kidnapped and imprisoned in the backyard of convicted sex offender Phillip Garrido for 18 years. During that time she bore him two children.

After the birth of the second child Jaycee wrote in her diary, "Sometimes all I can think about is the way I look. I feel ugly because I'm fat and my face is so awful, full of pimples ... It makes me depressed the way I look now ... I hate feeling down. I want to be happy."

That's astounding. Why would a woman who has been tied up in a backyard for most of her life, and just given birth to a child she unwillingly conceived with her captor, care about her appearance?

Who cares about losing your baby weight when you have lost your freedom, your family and your innocence? You'd think she'd have bigger problems to worry about than the rolls of fat on her stomach.

Of course she did have bigger problems. But they were so horrific as to be almost inconceivable. They would also appear to be unsolvable. About the only thing you'd think you could control is your body — including the amount of fat on your body.

You can see how Jaycee Dugard would have loved to believe in the fantasy that one day, when she lost a few kilos and had clear skin, her horrendous life would be better.

It's an extreme and horrific case. Few women have endured the life she led and survived. But, in this respect at least, her story is that of everywoman: when we can't control our external environment, we turn inwards and focus our frustration, fears and anger on ourselves.

We cling to the fantasy of dieting redemption, despite all evidence to the contrary, because if we believe that our biggest problem in life is our weight, then we also can believe that once we lose our weight our problems will be solved.

The problem with this way of thinking — other than the fact that it doesn't work — is that while we are focusing on our bodies we are distracted from what is really upsetting us.

We may not be tied up in a backyard and deprived of our freedom, but many of us are tied up with other things that make us unhappy. But you don't have to be Einstein to work out that we can't solve the real problems in our life if we misdiagnose the cause. It is insane to persist with the delusion that the source of our unhappiness is our fat and that cutting out a food group or drinking diet shakes is the answer.

Kasey Edwards is the best-selling author of four books; 30-Something and Over It, 30-Something and The Clock is Ticking, OMG! That's Not My Husband, and OMG! That's Not My Child. www.kaseyedwards.com