Does Clomid and Letrozole make you gain weight?

So I have pcos. I have known since I was 18. I got married to my husband almost 4 years ago, and I struggle to get pregnant and when I do it has ended up in 3 chemicals. While in the US my OB did several tests and ultrasounds on me and said she couldn’t find anything wrong and everything was normal. The last test was last year and all she gave me to help me conceive is metformin. Now at this point I’m in my husbands home country and just saw an OB here who showed and told me I have several cysts on both of my ovaries from the pcos and he recommended either Clomid or letrozole but that he wanted me to lose weight first because it will make me gain more weight while I am on it and he wants to lower my chances of having harsh complications if I were to get pregnant at my current weight, he also said that the weight loss will help make the cysts go away. But if not I will probably need surgery. Is it true that both of the medicines cause weight gain? I know I need to lose weight anyway but I am just curious because my sister was on Clomid but her weight didn’t go up a lot.