That would be plain discriminatory when it comes to people's eating habits, and unfair. I'm all for promoting healthiness, but making a certain food more expensive merely because it is unhealthy is stupid. It would be bad for the local economy as less people buy those products.
Sometimes raising taxes is necessary, because when the government screws up any way of fixing it will always require more money. If y'want to raise taxes, raise sales tax which applies to all products. This way, you do not negatively affect the economy and are not discriminating. Alternatively, raise fines for those who commit crimes as unlike the taxpayer they're actually doing something wrong.