Palm oil and its countless derivatives go into a LOT of products once you start paying attention to it.

If you are going to do something like that, and I'm not sure I'd support it at all, it'd have to be well-designed and intelligent, not "tax all sugar" or "tax all palm oil". But I suppose that in much the same way that VAT is higher on some less vital products than on others in many countries, you could distinguish between various categories of food for the VAT or other sales tax. The government "punishing" fast food that way certainly seems no more arbitrary or interfering to me than their decision that books get the low VAT rate but CDs and DVDs do not, which is the case in Belgium at least.

In any case, information campaigns and the like are probably better, though of course those cost money instead of raising it...