wickerman - you sound like a really nice woman with a lovely sense of humour and this issue really does not matter one jot to men although I can see why you think it might.
You should not feel the need to make any pre-announcement or forewarning. Indeed, you should say nothing at all because no man will say anything detrimental and he will not think it either. If he did, he would not deserve you. Indeed, he is more likely to be saying a silent little prayer of thanks that a nice woman actually likes him enough to want to be with him. Meanwhile he will also be attempting to hide his own sagging moobs, hold his paunch in and be desperately hoping that he is able match up to your expectations.
My DW had the same feeling as you after DS2 and she has sage advice for all women after having chldren. Go and get a proper bra fitting and treat yourself to some nice underwear.
She was amazed to find she had been wearing the wrong sized bra almost all her life and the place she went (John Lewis bra fitting service) said something like 50- 70% of the women that they see are in the same position. Wearing nice underwear with a good bra of the proper size made her feel much more physically comfortable, made her clothes look and fit better and gave her a lot of confidence. It was quite nice for me too.
What is amazing about this thread is the vast gulf between the nice things men are saying and the self doubt that you (and oother women) are expressing. The problem is that there is really no channel at all by which normal men can communicate how they feel about normal women in RL. Even if they tell DW/DP they are only half believed as they will tend to think DH/DP is just telling them what they want to hear.
That leaves women unsure about what men really think about female bodies so they look at images in the media and use that as their reference point. Young women and teenage girls are obviously very susceptible.
I tend to agree with others on the issue of porn but I think it even more insideous how the media and fashion retail industry constantly bombard women with distorted body images in their advertising. The images portrayed there are plasticised and digitised and are not actually very atrractive to men at all but are undoubtedly aimed at women and held up as some sort of ideal they should strive for.
Good luck in your quest - enjoy yourself and stop worrying.
whomovedmychocolate - your two "hard boiled eggs in turkey neck" comment made me . I must admit I did cast a slighty worried sideways glance in the bathroom mirror this morning just to check, like [male vanity, moi?]