Some context: My coworker and I are foreigners working in Japan as IT developers.

Our team works from home 2-3 days a week.

This coworker is working fully from home (too far from workspace).

Issue:

As I had to delegate part of my tasks, I recently discovered that one of my coworkers is pushing himself way too much: working a lot of (partially hidden) overtime, skipping or rushing lunches, not taking a day off when sick, etc.

It took time to realize because he works fully remotely, and he doesn't report that much on his progress.

The reason I realized late is because first it was mainly based on references he said. But, with coworkers and Scrum Master, we talked to him and confirmed with the situation

What I tried:

• Telling him that we work as a team and that we can all support each other.

• That we can talk openly when we need to adjust timing / deadline / resources.

• Telling him that taking breaks and proper sleep and lunch is helps us to work better.

• Suggesting he could take a day off when he was sick and that we culd follow-up / continue on his tasks.

• Warned my Scrum Master twice.
  Thus, my SM sync with my coworker.

But even after all that it seems the situation has not changed.

This coworker will easily say he thinks he is not capable etc., but if I try to ask more details he settles back.

I wonder if there is any (other) approach that could be more effective.