why is it the govts responsibility to protect stupid people from their own stupid actions?
Because the government has a vested interest in keeping the population (at least somewhat) healthy. Try being an economic or military superpower when a significant percentage of your population are obese and suffering from diseases like type 2 diabetes. You won't get very far.
Seems like we're trying to circumvent natural selection.....let these people take themselves out of the gene pool....and maybe we'll have fewer stupid people in a couple of generations?
How on earth would they take themselves out of the gene pool? As long as they survive long enough to reproduce, they are still in the gene pool and they will have "won" the evolutionary contest. Eating junk food and drinking tons of soda will not kill you before you are old enough to reproduce, but it will make you unhealthy, unhappy and a burden on the heath care system.
I've honestly started to wonder, with all the problems we're seeing in modern kids, autism on the rise...so many of them with food allergies (I never heard of anyone almost dying from PB&J sandwiches at school when I grew up, and we ALL ate them)...etc.
People fail to understand that in biology, "fitness" has a very specific meaning, namely that you are fit enough (with respect to your environment) to survive long enough to reproduce. As long has you meet those criteria, you are, evolutionarily speaking, "fit". Thus the requirements for being "fit" in human society have essentially remained unchanged since you were a kid, barring perhaps a few vaccines.
As for the alleged rise in autism and food allergies, I think that's simply a case of parents have a greater awareness of these phenomena now. In earlier generations, children with allergies might simply be seen as not liking certain foods and children with autism would just be considered a bit "odd".
Saying that we shouldn't encourage people to eat healthier foods because they will "take themselves out of the gene pool" is almost as bad as saying that we should ban eye glasses. <sarcasm>After all, the people with poor vision will tend to get into fewer accidents! And if we're lucky, these accidents will kill them in childhood! Why, in a few generations we might cure all eye diseases! </sarcasm>