“…or you can suggest that the girls try to lose some weight which may solve the problem.”
This will most certainly NOT solve the problem. If a man is not attracted to (I won’t go so far as to say repulsed by) an overweight woman, he doesn’t have to go out with her, and she can find a man who does find her attractive. But to say that at this point she should lose weight is not fair. Men have different tastes in women; some actually find heavier women more attractive, just as some prefer blonde hair and some prefer red hair. Should a woman dye her hair to become more attractive to certain men, only to then become less attractive to others? So it is with weight.
Furthermore, a woman who is told that a man is only interested in her if she is thin will naturally lose some self-confidence. There are so many single women out there who are only getting older, and I’m sure many of them, even if they present a self-assured manner, have thoughts late at night such as “What’s wrong with me? Why aren’t I married already?” Suggesting that they have to lose weight or change in any other way only confirms this doubt that maybe something is “wrong” with them and they cannot find a shidduch just the way they are.