Succinctly: Losing weight is not intrinsically healthy; Gaining weight is not intrinsically unhealthy.
I realize that desire to lose weight is one of the key motivators for people to address their health. However, I think it is important to talk to people about their desire to lose weight and suggest reframing those thoughts into a healthier outlook. Often, losing weight isn’t actually the real goal it has just been conflated with the real goal. The real goal is often to become thinner/smaller, healthier, or both and I think it is helpful to acknowledge this. For people I talk with I suggest that the goal should be getting healthier/fitter/stronger and letting the body figure out it’s optimal weight and size. I also suggest, to those who seem to be motivated by improving their physical appearance, that healthy people are perceived as more attractive than unhealthy people. I think many of us have had experiences of being around people who were vibrant and fun and have bigger than average bodies and those who have smaller than average bodies who are listless and dull.
I’m not making a claim that gaining weight is always a sign of improving health or that losing weight is always a sign of declining health. I’m merely suggestion that that could be the case. People get excited about losing weight and assume they are getting healthier. But if they are starving themselves they are, indisputably, not getting healthier. Also a person who increases their exercise and improves their diet may gain weight as they increase bone and muscle mass, even if they are burning fat. If these people focus on the number on their scale they may feel down about “not making progress.” It may be helpful for some people to tell them to take their measurements (waist, hips, bust) as that may be a more accurate measure of how their body size is changing, which is what many want in the first place. As people’s bodies optimize in response to improved health they may well find they lose weight and size but this should be seen a sign of improving health rather than better health being seen as an effect of losing weight.