The state has the right to not allow to you to smoke, to do drugs, to drink until you are 18 or 21 (depending from the country) etc. This means that the state has the right to tell you what to do with your body, whether this is bad or not it's not on topic.
I don't see what's wrong with it. If the people can't stay healthy by themselves, the government should step in and help. There's no reason for a person to be over weight (in most cases).
There are a number of reasons people gain weight, it's not just an unhealthy lifestyle.
During my student teaching, I was insanely stressed, and I gained 10 pounds in three months. I spent so much time working that I never got to exercise. I know it's unhealthy, but the last thing I needed was for someone to step in and force me to be healthy. It would have hurt me more to force me to exercise than work.
When I quit smoking, I gained 15 pounds. Smoking increases metabolism and digestion speed, so quitting makes you gain weight. I gained some weight, but in the end, the health benefits of were much greater.
Also, there are a lot of heavy people who are perfectly healthy. My brother is skinny and muscular, but is plagued with high cholesterol. Should the government force him to take cholesterol meds? It's ridiculous to believe they should get into people's health like that.
I'm a bit on the pudgy side, and I have no serious problems. Everytime I get a physical the reports says the same thing: Perfectly healthy. Why should I bother losing weight if I don't want to, or don't need to? I'm perfectly healthy and happy. A government can't force me to be skinny.
The media has convinced the world that fat people are bad. We have size 0 models plaguing our magazines and ads. Anorexia and bulimia are becoming common. In the day and age of Capitalism and advertising, people are becoming afraid to fat people. It's absurd and needs to end.
The government has no right to outlaw being fat. Some people say that inside every fat person, there is a skinny person waiting to be let out, but I say outside every skinny person, there is a fat person waiting to be let in.
Imagine if this policy were implemented on Eskimos, or if the reverse were done. Many cultures see fat people as the most beautiful and being skinny as indication of severe poverty and something to be pitied by all.
If they can tell you you can't end your life why can't they tell you you can't be fat? A legal precedence has been set that the government can tell you what to do with your body.
If your country employs a public health care system as mine does, you can see how the obese have a direct adverse affect on people of normal weight.