It's an interesting point, one which I have some experience of. When it comes to 'hard drugs', I agree with what has already been said by Skip0110 and Blake for example. However, it's the much more widespread use of softer drugs (esp. alcohol) where the issue becomes a bigger one. I reckon that the
abuse of alcohol (or any other drug) has as one of it's social consequences, a strong tendency to result in poor eating habits. It is a well documented fact that this is the case.... irregular eating habits, poorer quality food (take-aways, or no food at all), lack of motivation (and even cash) to properly stock your fridge etc., all add up to a break-down in the habit of eating properly. Since alcohol is by far the most widely abused 'drug', it is a good example to illustrate the point that the two things - drug abuse and diet - are not two separate entities which can be off-set against one another or even considered as stand-alone issues.
One thing I think is that the development of decent eating habits and drug abuse are mutually opposed, since one requires discipline and the other is the polar opposite... For that reason, I think the 'drug user who eats decently' scenario can be considered largely irrelevant, since I would go as far to say that a drug user who eats decently is probably not yet a problem user or an addict. Of course, some individuals can and do abuse certain drugs (alcohol being the only 'drug' that applies to the people I know in this category) and still eat pretty well, but they are definitely in the minority. The majority of people I know who drink heavily do not have decent diets at all.
As for the issue of whether eating badly is worse than drugs (if it
were possible to separate the two issues, which I don't believe it is, but anyway), I'd say that drugs were worse full stop, since even eating badly is better than not eating at all, and (like has been said already) you can always do something to counteract the negative effects of a poor diet (take supplements, do exercise, change your diet etc.) whereas drugs typically have a tendency to do much more serious and sometimes irrepairable damage to your body and/or mind. Drugs such as LSD (even in low doses) and marijuana (in higher doses) can have a devastating effect on the mind, whether or not either drug can actually physically kill you. In the case of LSD, which is particularly psychologically risky, one single dose can be enough to ruin your life forever (I'm unfortunate enough to have second-hand experience of this)...
i hope no one looks at me differently now that i spilled that dark little secret of my life. if i am banned for this post, I probably deserved it.
To my knowledge, there is absolutely nothing wrong whatsoever with discussing these issues in an open and adult manner, so there is no way you'd be banned for a post like yours!! I think it is great that a forum such as this gives people like ourselves a chance to 'get things off your chest', even stuff you might not feel comfortable talking to people about face-to-face. It would be a sad day indeed if this was not the case.