You so badly want to help. Plus, you have very real knowledge that can assist those you care about. But, you know that advice is so rarely followed. What to do? Suggest measurement.
Consider the Fitbit craze. Everyone, from the most obese down to those possessing visible ribcages, knows that walking is healthy. Yet, almost nobody walked enough in a given day. Action, not information, was the issue.1 Then these same allegedly unmotivated, uncompetitive, and lazy folks were give a simple step counter. No advice. No instructions. And BOOM! neighborhoods were suddenly overrun with walkers striving to reach the arbitrary figure of 10,000 steps. Better still, these walkers were now truly open to receive advice since health tips no longer carried the burden of something to put off and feel guilty about, but were instead genuine methods to be added to the self-started and already underway lifestyle transformation.