@neptuneblue,
Sometimes just a little push back can work wonders. Every body has a style and you know your husband better than any one here....but if my husband started to quiz me about my lunch, (half the time I probably wouldn't remember) I think i'd first say: Yogurt, no wait, that was breakfast....oh shoot, I'm blanking.... no, no, WAIT!! I did have yogurt at lunch..Chiobani Mango, yep, yep, thats right, I love Mango...what did you have Sweetie?
I'm not sure if this is something you would find works for you ....but my husband always opens the bills first (not a problem for me) but for several statements he would look at the statement and with an edge of disapproval would ask "did you spend $300 at Nordstroms"? I would look at the statement and think for a minute, I would remember, then say, yes...I bought those towels we needed. After one to many times being quizzed it started to really annoy me but its went on for over 6 or 7 statements with me responding 'Oh shoes, Oh the dress for the wedding or oh it must be the blender I bought. But then this one day I'm up to my elbows cleaning shrimp and he asks "Did you spend $500 at Macy's...... , I looked at the statement..looked shocked and then said "Did you spend $345 at Home Depot?", He rolled his eyes and said 'alright'. (only a tiny amount of steam rising from his head)
The thing is, he really doesn't care I spend money (especially since our individual income is practically identical) I suspect a teensy little bit of him 'a tiny little bit' thinks he might not be in charge, but we both know that ship sailed 40 years ago, we agreed we would be equal partners. Neither one of us would bring home a new car, or contract for expensive remodeling, sizable purchases are always discussed...........but I'm not going to call about buying a new purse or shoes and he doesn't call to see if I think it's ok for him to buy a new pair of shoes.
I know it's not a dealbreaker that he wants to know what you had for lunch, but see if you can't cajole him out of the habit. I'm not saying lie or deceive just find out what is worrying him so much about diet.