I think smoking is particularly hard because most of the really bad effects come much further down the line. You can smoke for years (even tens of) without much problem and if you do some sports even the cardio/breathing effects are largely mitigated (I know, this is what I do).

So, it's easy to only think about how good it makes you feel at the moment.

But alcohol will show nasty side effects rather sooner than later, it will show on your face, you will feel liver problems very fast and since you are in a secondary state when inebriated you will seem out of place when not in that state.

Both of those substances have the particular effect that if you use them repeatedly over a short (1-2 week) period of time in moderate but sustained quantities, you will get chemically addicted. This is nasty and the reason why every parent tries to make this fact known to their children (more or less successfully depending on method).

Food addiction in my opinion is very different, it comes purely from psychological factors and should be very easy to correct on time. It's not something that comes around in 1 week or 2. Even if you overeat 1000 kcal (1/3 more than the average of 2000) over the course of 2 weeks, you would only gain 2kg of body fat at worse. It's really a very long sustained process to really become obese, it's not like chemicals that can get you in 2 weeks max.

While it's hard to lose what you gained (you basically need to starve a little bit) it's not that hard to make adjustment to life choice to avoid making the situation much worse.