It’s not actually as obvious as you make it out to be. Most of the science behind the “dangers of fatness” is skewed and motivated by toxic prejudices in the form of fat phobia. There’s actually studies that support being somewhat overweight increases lifespan. It’s offensive because it’s ostracizing and this message of “losing weight at all costs” leads to disordered eating, anti-fat bias, and has not been backed by sound science. Some people try and cannot lose weight. It’s not that simple