To lose weight, all you have to do is eat less and exercise more.

Easy, isn't it? So why can't you?

There are many emotional and physical reasons why we put the weight on in the first place. Having said that, many of us that are overweight manage to keep it on for longer than makes sense.

Take my friend Hannah (not her real name). Well-liked for her hospitality, she feeds you plenty whenever you go to visit. Her kitchen is full of cakes and snacks. Her living room is scattered with chocolates, biscuits and cookies. She tells you of all the meals she has cooked for her family that week and gives you new recipes that she's found. She's tried them and they're delicious.

Can you imagine if Hannah had been a heroin addict?

Take my friend Hannah the heroin addict (not her real name). Well-liked for her hospitality, she makes sure she has a good supply whenever you go to visit. Her kitchen is scattered with burnt spoons and discarded bits of aluminum foil. Her living room is full of the sickly-sweet smell of brown. She tells you of how the social services have taken the last remaining child off her that week and gives you the number of the new dealer that she's found. She's slept with him and he's given it to her cheap.

Not so homely and cuddly anymore, is she now?

Overeating is an addiction. Many people who overeat also over-exercise. Some both overeat and deliberately under-exercise. And every time I think I have heard all the excuses, I hear another, even more inventive one.