"break one's habit of", "break the habit of", "break one's .... habit", are they formal?

Question

Consider the following sentences:

1. He is trying to break his habit of biting his nails.
2. He is trying to break the habit of biting his nails.
3. He is trying to break his nail-biting habit.
4. He is trying to stop biting his nails.

In my native language, sentences 1 to 3 sound formal because the word "habit" is used. In casual conversations we would say the last sentence.

Is this the same in English? Do sentences 1 to 3 sound formal?

Answer 1

1 & 2 sound wrong, with to many he/his's flying around. I would also question the use of break in 1-3. Does he want to resume biting his nails at a latter date? Break can be End or Interrupt. Number 4 is fine.

Number 3 I would modify

He is trying to stop his nail-biting habit.

This format is quite acceptable

From that point on, he apparently developed a bad drinking habit and struggled with various health problems.

Arguably this arrangement would sound more formal.

He has a bad habit of biting his nails, which he is trying to stop.

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