Perhaps I have a slightly different take on this than others might…
It sounds like your wife is not just a bit “controlling.” Based on your post, It sounds like she is way over the top. This may have resulted from her assuming over time that being this way toward you is okay with you.
Based on everything you’ve shared, it’s pretty clear that her trying to control you is not okay with you. Or, perhaps, it’s just finally gotten to the point where it’s no longer okay with you.
You have the right - in any relationship - to tell others where your personal boundaries are. In fact, I’ll say it more emphatically… you have a responsibility to yourself to tell others where those boundaries are if they’re not being respected. And it sounds like they are not.
Remind your wife, politely but firmly, that you are an adult and what you choose to put in your own mouth is not her business. Period. Same goes for your kids, friends, neighbors, etc.
Would you ever consider treating your wife the way you’ve described she is now treating you? I sincerely doubt it.
At some point, if your personal choices as to what you want to eat for the sake of your own good health are treated by your wife with the kind of disrespect they are now, then I’m afraid you may have no choice but to reevaluate whether this is a healthy marital relationship for you. I know that’s a serious statement and so I don’t make it lightly.
What you are doing to improve your health is admirable. I wish you the very best in regaining the control and respect you clearly deserve over your own body.