1 : Skinny people are often vegetarians. Vegetarianism has a known correlation with speaking German and invading Poland, and should be discouraged.
2 : Diets make people grumpy, and grumpy skinny people are more likely to beat up people with axe handles than cheerful fat people who don’t want to let go of their Big Mac to do so.
3 : Skinny people are more likely to catch you.
4 : People are irritating. Extremely fat shut-ins can’t get out to bug you, and die and get out of the way earlier.
5 : When Peak Oil, Global Warming, the End Times, and illegal immigration all combine to bring doom, fat people are better eating for when the food runs out.
Therefore, obviously being skinny should be discouraged. I suggest a $100 year-end bonus for every pound over the citizen’s medically ideal weight, and a $100 penalty for every pound under added to a basic charge of $1000 a year for everyone at or under their ideal weight.