It's a low-grade, plausibly deniable, passive-aggressive insult. I can assure you, twenty years ago, maybe even ten years ago, if you told a "woman" who'd gotten fat since you last saw it, "you're looking healthy", without any other comment that it was looking good or pretty or whatever, then it would be understood that you were commenting negatively on the weight gain without the surface appearance of being mean. The idea is that you're saying "you're  certainly not wasting away" but more subtle. This article does exactly that. An old picture of Amanda is captioned as "pretty" and many words are devoted to neutral observations like what it's wearing, but nothing positive or negative is said about its current appearance except "healthy". And come on, we all know the person at the Daily Mail doing these write-ups of humiliating photos of washed-up celebrities is a "mean girl" shitlady.