The true answer is, yes many boys will say no on weight.
however, I have plenty of married friends who were overweight. Or who took medication, or who had a genetic issue, or whose parents were geirim, or who were very poor family, or who had a sibling with mental illness or OTD.
There are plenty of mumim in shidduchiim. Most people have at least one. If your worst mum is being overweight, you will probably get married. If you have emotional issues with relationships, you will have a much harder time getting married that you will with any or all of the mumim above.