I’m not the OP’s friend. However, I have been the target of many “helpful, concerned” remarks, and I have talked about these kinds of remarks with other people. The remarks, especially the mocking, needling remarks are not helpful at all. They are hurtful, counterproductive, and not the remarks that a true friend would make.
I will tell someone, once, that I don’t find the remarks helpful in any way. And then, if they continue, I will avoid that person.
I have been in the shoes of the OP’s friend. Whether you think my reactions are irrational or not, they are common reactions. You advocate sitting down and talking to the friend about the consequences. Anyone who has an IQ above room temperature has heard all about the consequences. Unless you are a mental health professional, and are asked for advice, you can either accept this person, faults and all, or you can accept the fact that you are likely to lose his friendship if you insult his intelligence by implying that he’s so dense that he doesn’t realize what his excess weight is doing to his health.
I’m a vehement antismoker. Going through a cloud of smoke will trigger an asthma attack and possibly a migraine in me. But I don’t say a word about or two people who smoke in the designated areas. If they’re over 18, I assume that they already know the health consequences. I only speak up if they light up in a nonsmoking area, and then I don’t say anything about their health, only my health. If they want to clog their lungs with tar, it’s NOT MY BUSINESS, as long as they leave MY lungs alone. If an alcoholic is drinking himself to death, it’s NOT MY BUSINESS. I won’t buy cigarettes for a smoker, or alcohol for an alcoholic. Similarly, if someone wishes to buy me an edible treat, I’m quite happy with fruit or cheese, I don’t insist that they buy me chocolate.
My best friend is helpful. We get together every week or two, and she has taken me to new restaurants, where it’s easier to make healthier food choices. It’s also easier to stay on my food plan if I’m eating with someone who’s NOT ordering the queso (cheese dip), which I dearly love, but which surely contains a zillion fat grams. And we always do something that’s physically active, that’s challenging for me but which stays within my abilities, too. She gave me ONE talk about how she’s concerned about my weight and health, but she hadn’t seen me for 30 years, when I weighed about 115, and when I was quite physically fit. Since then, she hasn’t talked about my weight, or about my diet. She just quietly helps me plan ways of better managing my diet and activity. And I provide support for her issues, too.