We&#x27;re somewhat off on a tangent now, but anyway:<p>While there has been plenty of disagreement in nutrition science, there&#x27;s also a lot of agreement. It&#x27;s pretty well established that highly processed foods that are loaded with sugar, salt and fat are less healthy than fresh vegetables. When the science changes, laws can also change, and we don&#x27;t have to have laws that are so specific as to make the &quot;perfect&quot; diet free and any other diet prohibitively expensive.<p>Examples like your friend that have a hard time controlling their calorie intake due to medical complications are pretty rare. But indeed, as you say, things are not black and white, which is why, in general, laws are fairly complex and it needs lawyers to understand them. It&#x27;s not like the current tax code doesn&#x27;t have any special cases for exceptional circumstances. But figuring out all the special cases needed for a tax code that rewards healthy behaviour is probably way out of scope for a HN comment thread.