I strongly agree with Tanya that taxes are unfair. People who eat unhealthy products are poor people to begin with.
Fast food helps them secrete dopamine, which is an escape from the arduous mundane life. If government imposes strict taxes on unhealthy products, it is highly likely that the life expenditure of the struggling population will increase, leading to social unrest.
Sam raises the relevant point that by taxing those products, the government can discourage people from consuming them and resolve health issues.
However, he does not mention that wealthy or middle class people seldom make unhealthy products their staple food. They care so much about figure management that they would prefer fat reducing meal. The opponent-processing nature of the brain makes it easy to become addicted. They try to avoid fast food at all cost, let alone if the government impose strict taxes.
Overall then, I don’t think taxing unhealthy products is a great idea.