A friend loves at all times, and a brother is born for a time of adversity. Proverbs 17:17 NIV Bible
There's an old saying, There are friends and there are friends. I think this Bible passages is saying, that true friends, become like a brother in times of trouble. I think that's the sign of a good friend. By this, I wouldn't consider that anyone who is your friend is true friend when things get rough, you are no longer popular with others, or your views are identical to theirs!
I had the reverse situation. I knew lots of people, but they ignored me or barely tolerated me when I was heavy. I was hurt when the treated me disrespectfully or they would ignore my thoughts and ideas, as if someone heavy couldn't have credible ideas to contribute. It was even worse when someone thin, would think about what I had just said, and would turn around and say those same things as if they were their ideas, and the others would rave about what a good idea or comment it was!
When Christ blessed me with an 80+ pound weight loss, all of a sudden, these so-called friends, were all of a sudden very friendly with me. They paid attention to me and respected my thoughts and ideas. The thing is, I didn't really consider these people as true friends, because of how they had treated me prior to the weight loss. Fortunately, the Lord has shown me, I'm not supposed to judge others and to forgive them, like He forgives me of all my many shortcomings!