Zippy I'm so sorry to hear that but glad it's sorted.
Remember that remarks of this kind, whether it came out wrong or what have you, have nothing at all to do with you and everything to do with the speaker's issues, loss of youth, fear of aging, mortality, and so forth. A few pounds or even sizes over the course of life, 2 children, etc., are not really the issue -- it is not as if you are seriously overweight or obese in any way. You may be a few pounds over your own preferred mark, but your partner needs to accept that after 2 children and the passage of time, he needs to flex as not every person will retain their same or similar shape &/or weight after the miracle of birth (twice).
If your partner is supportive of your efforts to improve your health, that is wonderful. If he is concerned that you are (gasp) aging just as he is and we all are...and that mortality is a fact of life...well, these are realities that he must confront and nothing he does or asks of you will change that. No one can put their insecurities or fears or unhappiness in the lap of another, even a partner, and expect them to solve things. (It would be different if he were confronting you over a substance problem or a behavioral addiction like sex or gambling, but that is not the case.)
Just as a BTW, you may want to take note if this is a one-off or if these sort of comments become more prevalent in future. It is always very disturbing to me when one partner puts the emphasis on weight or appearance or core "attractiveness" of some sort. Particularly if there is any inequality in the relationship whilst these comments are being made. For example, one partner makes more money, &/or there are children that will typically be left impoverished with mum if dad leaves, OR one partner tends to regularly argue or pick fights, or cheats, or regularly threatens to leave or not to commit, or or otherwise seeks to constantly destabilise the relationship.
Here is my little vignette from real life...and as a result I really have no respect or tolerance for these sort of barbed attacks and find them to be extremely shallow, for the most part.
My mum endured this for many years from my father, endless scrutiny of every pound and wrinkle, and she was quite lovely really. He ended up cheating on her relentlessly all whilst threatening to leave on a regular basis, and also trying to destroy her self-esteem about her looks. Because of the financial inequality and the fact that there were 2 kids, at that time she did not consider leaving and just endured. Which in many ways is quite noble and in many ways is a shame. Later, after 20+ yrs of marriage & divorce, he ended up marrying a woman of
very similar build and a similar appearance and colouring as well, dark-eyed and dark-haired, tanned or dark. (Absolute opposite of me, LOL).
It really had nothing to do with my mum or the other woman, not really. It's primarily just that one marriage occurred prior to his full-on mid-life crisis, and one marriage occured after. I should mention my dad
always had an obsession with aging and youth and the latest nutritional fad promising eternal youth, and that he
always had a morbid fear of death since his granddad & great-granddad had died young of heart disease (which is easily managable now). However it is more common for one's fears to come to the fore strongly around mid-life (if not earlier), whenever one begin to seriously confront the issues of aging and/or mortality.
Nothing really changed except my father. Dad has become a bit more appreciate of those in his life, & a teensy bit less obsessed with dying,
and perhaps a smidge less superficial regarding youth, fitness, and appearances, and so he has been a bit easier on wife #2.
This is a man in his mid-sixties, so to be honest there is often a self-imposed limit on growth in any one lifetime
...and so it's hard to say at what point many will overcome their superficiality or their mortality issues.
Since he is tall, lean, and always fancied himself quite handsome, though, dad hasn't ever had much compassion for those who are more naturally pear-shaped
and cannot always manage weight as easily as he at all points in their lives (i.e., most women after childbirth, whilst breastfeeding, etc. ).
Luckily, the rest of have compassion for him and love him despite himself
All the best and much love and light to you
7L