Skinny people, I don't understand you?

Anonymous
Don't worry this is no hate, because I am a skinny person too. A while back I saw this couple (they were very fit.) tell this lady who was obese to her face that she needed to work out and lose weight. So she nodded her head and said okay, so I offered my help to this lady for a new diet plan and fitness routine. So fast forward and its been about 5 months and the lady has all together lost 67 lbs. And the couple return to laugh at her and tease her on her weight loss and put her down. Now I resolved this situation, but I do not understand how some fit people can tell someone to lose weight and then mock them for doing it?
Skinny people, I don't understand you?
11 Opinion