you SHOULD stop vs HAVE TO stop

Question

I've been learning grammar for quite a while now, but I still come across some "grey areas" where I don't quite get the difference in meaning.

Let's say my friend wants to lose some weight I can tell him:

1. You should stop eating that much
2. You have to stop eating that much

As I understand it, both options are natural in this context, but 1 means that I think it might be a good idea and useful for my friend to stop eating that much, but it's not the only way to go and there are other options to lose weight, however, this one is the best of the options.

and number 2 means (as I understand it) that in my opinion, him stopping eating that much is the only way for him to lose weight, all other ways don't seem effective or appropriate to me.

Do you think I correctly understand the difference in meaning?

Answer 1

It's a good question. A dictionary will tell you that "have to" is an order that implies some obligation to obey, but often when it is used the speaker has no actual authority over the person they are saying it to - it is just to make the statement more emphatic.

You should stop eating that much.

"Should" implies that there would be good reasons to stop eating, but it is still a suggestion, not a command.

You have to stop eating that much.

There is likely no way that the speaker can force the other person to stop eating as much, but it adds emphasis, suggesting that the reasons for doing so are compelling.

In other contexts though, "you have to" is an order. For example, if someone said "you have to leave now", it would mean you must leave immediately.