How further can it go?

[AlexAD]

Hello.

A friend of mine has been on a meatless diet for 3 months.
Can I say, 'I wonder, how further can it go' to mean how further will it be lasted?
If not, how else would you say that?

I would be grateful for any mistakes you might correct in the post.

Thanks, Alex.

[bhaisahab]

Hello.

A friend of mine has been on a meatless diet for 3 months.
Can I say, 'I wonder, how further can it go' to mean how further will it be lasted?
If not, how else would you say that?

I would be grateful for any mistakes you might correct in the post.

Thanks, Alex.

"How much longer are you going to stick to this diet" is one possibility.

[AlexAD]

Many thanks.

Can anyone think of a shorter question (like mine)?

[SoothingDave]

How long will it last?
How long can this go on?
How long can you keep it up?