Shouldn't we cut the tax on cigarettes and instead tax people who are too fat?

Recent data has shown that people who smoke die younger and quicker than others and thus draw less on our overburdened social safety nets. Obese people on the other hand tend to kick around a lot longer and cost more in the way of both medical coverage and social security payments. The whole point of taxes on cigarettes is to recoup money the state has to spend on people who are living an unhealthy lifestyle but in reality, smokers cost less without even including the taxes paid.