OP here: Thanks for the advice! I will try both the medical excuse, turning the conversation around and avoidance. (And ignore the 'desert' comment!) Thanks very much.

I love PP's idea about the medicine. I am VERY VERY thin, and recently DID go on medicine which has left me bloated and with a gut! I look 3months pregnant ( IMO)!! I however, did have abdominal surgery and couldn't walk for nearly 4 months afterwards. I had no 'gut' going into all this, but the medication and lack of activity and probably eating to pass the time helped me put it on. I would totally use that excuse!!! That would make someone feel awful and hopefully mind their own business!

I totally know how to handle this (my mother is just like your MIL), but it's kind of manipulative. Essentially, you re-direct the comment where it belongs: on her. Here's what I mean. Most of the time when people are like this they are actually projecting their own fears about themselves onto the people around them. So, if your MIL is picking on everyone else about their weight it's because she's actually worried about her own.

The way I handle this with my mom is to turn it back on her. Either I tell her she looks like she's gained weight too, which freaks her out and then we end up talking about pilates all night; or I compliment her on how slim she's looking and change the topic (e.g., is that a new purse? it's lovely. You have such great taste. Where do you buy your clothes?). Either way, your goal is to change the topic and get her talking about herself. Just keep doing this every time she brings it up. Unfortunately, there is no way to shut it down permanently, but you don't have to get stuck in it either.

Good luck OP!

Tell your MIL that you appreciate her concern, but that your weight is none of her business. Then enjoy your cruise.

OP, can you make a point of doing special activities with the family you like (not MIL), and hope that the fun cruise distractions and the diluting effect of others will limit your exposure to MIL? I think you may be in a no-win situation as far as finding that perfect phrase that will politely keep MIL from making rude comments. If you can avoid her as much as possible, that might be best.

I'm very sorry - I have a few relatives and in-laws who are like this, and my strategy is to limit interaction and / or try to schedule lots of activities as a distraction and to help, for lack of a better word, dilute.

OP I feel for you, we spent time with my in-laws during a 2ww and it was torture, they are both very judgmental about weight gain. I packed on about 15 lbs during our first IVF cycle and the prog made me so emotional, I felt so vulnerable at that time and my DH realized his parents and my hormones were NOT a good mix. I hope you get through it without smacking anyone

We have already committed to a cruise w/ DH's family during the 2ww. This will be our second time (first w/ FET) and last time I was very bloated and uncomfortable. We have decided not to tell DH's family about our journey to parenthood; they're just not understanding and, esp my MIL, are very judgmental. My MIL likes to comment on people's weight - I have heard her tell her daughters and she has made comments to me about weight gain, the importance of diet and exercise, etc. I want to play in the pool w/ my neices and nephews so I don't want an illness excuse. And I certainly don't want to feel guitly about indulging in desserts. I know she lacks boundaries but I'm too vulnerable right now; I want a gentle yet respectful "I'm fine and unconcerned." And it would be wonderful to have a pre-emptive comment, I don't know what that would be, but something about how I know I've gained some weight and am puffy but it's fine b/c .... TIA.