In recent years there has been an increasing focus on the problem of obesity in Western societies. While valid points are occasionally raised, a lot of obfuscation goes on. For instance, Europeans commonly believe that Americans are much fatter than them, which is total bollocks, and people blame McDonald's "cultural imperialism" for their problems, which is even dumber. Take a look at Morgan Spurlock Watch, an excellent blog run by a Cato Institute analyst, which is dedicated to debunking, you guessed it, "the silly hysteria perpetuated by Morgan Spurlock," the director of Super Size Me and author of Don't Eat this Book. Also see AtlanticBlog, which makes an interesting point on Paul Krugman's proposals - and make sure you check out the comments there.
People should be able to freely choose their diet, without state intervention. Where the state does have a role is in ensuring that companies furnish the consumer with accurate information on which to base these decisions, and I don't mean state mandated anti-fat propaganda on packaging.
Here is an excellent example where improvement could be made. By law the order in which ingredients are listed on packaging must follow the order of prominence each ingredient has in the product, so if sugar is the largest component it must be listed first. Since listing sugar as the first ingredient looks bad, it is common practice in the food industry to use different kinds of sweeteners (which are considered separate ingredients) to notch up something that sounds better.
For instance, if the main ingredient of a breakfast cereal is sugar, the producer will break the sugar part up into corn syrup, sugar, malt extract, honey etc. so that the cereal component gets listed first on the ingredient list. It would be easy, and cheap to require different sugars to be listed as one ingredient (with the breakdown of the various components in parentheses) so that this trick could not be practiced. No doubt it would be a more honest representation of reality, and people would be able to make a more accurately informed choice.