Yes, but only if we also force all who are deemed abnormal to undergo normalizing treatment. If we aren't going to force the short to be surgically stretched, or the gay to go straight or the skinny to go to skinny camp then I say it's not fair and the fatties can stay fat.
Seriously though, people are fat for many reasons. They are free to eat and do as they like. If they pay into a health insurance company than they should get equal care. Like smokers and heavy drinkers the fat may have to pay more due to their lifestyle choices, but it's their right to eat, drink and smoke what they want. I don't want to live in a country that tells people they have to be "normal".
Instead we as a society should encourage healthy lifestyle through education. Schools should offer healthy but tasty meals to get kids to enjoy eating healthy. P.E. should be mandatory and well funded so kids learn to have fun outside. Health class should also be mandatory so all kids learn how the body works and why inactivity and bad diets lead to obesity and diabetes.
Just because you decided to get healthy and lose wait, (congrats, good job by the way), it doesn't mean you have the right to force anyone to live your lifestyle choices. This past year I decided to take my health seriously too. I've lost over 60 pounds by exercising and eating healthy. For me it's about health, not my appearance so I changed my lifestyle instead of going on a diet. But I would never tell a fat friend to drop the doughnut and pick up an apple. My weight loss has encouraged friends and family to get healthy and they've asked for advice so I happily gave it to them.
Educate, don't dictate.