How can I convince my religious Christian stepfather to stop fat shaming and diet shaming me without coming off as a smart-a** punk?

I'm at 205-210 pounds depending on the day; 210-215 to account for water retention. I'm 5'7" tall. I exercise on almost a daily basis. I typically burn 200-400 calories each day.

Although subdue, my stepdad either plays nice, acts like he's teasing me, or flat-out lowkey judges how much I pay on products which I normally buy for the family. The irony is that they don't even want what I buy; but I want what they buy.

My family is Christian, religious; and my stepdad is a self-proclaimed "very righteous" person.

When I give myself a 3- or 4-, even 5-hour gap between meals he always conservatively exaggerates when I last ate, acting as if it was one or two hours ago.

I have to laugh it all off because he doesn't like being corrected; my mom and my dad do not want me correcting my stepdad, and they are very religious people too.

Something sketchy makes me want to leave my religion, but not until I bear children of my own. I still feel pressured to vote Republican because a lot of people my age who are chads and attractive girls are right-wing or Trump fans like it's trendy. Coming from Southern California.

Updates
1 y
My mom tells me I can eat whatever I want since it's my body and my decision, but never corrects my stepdad when he is being an idiot. Both are betraying me and this is the real reason why they don't want me back on social media.
Updates
1 y
Sometimes he'll use "inflation" or "daily allowance" as an excuse to get me to stop eating.
How can I convince my religious Christian stepfather to stop fat shaming and diet shaming me without coming off as a smart-a** punk?
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