Again, not publicly calling anyone any names, but funny enough two months ago (would be about when his wife’s imposed strict diet just ended) our op was wondering if going on a strict diet would help his joints.
I’ll just point out (again) that losing 55 pounds in six months is a loss of two pounds per week, which is not rapid weight loss. It’s unlikely your weight loss has damaged you in any way, short of completely eliminating a food group. But a doctor could check that.
And there’s no way to answer your question because: a strict diet of WHAT? A strict diet of arsenic? That will kill you, yes. A strict diet of a variety of whole, unprocessed foods will likely improve your health, perhaps dramatically if you eat poor variety and/or a lot of processed foods now. I know strict vegans who are quite healthy. I know meat eaters who are too. I know people who have to be strictly gluten and dairy free because those foods aggravate their existing health conditions. I know people who have no food intolerances at all.
In order to figure out your personal, ideal, healthy diet, you are going to need to learn about nutrition, cooking, and how to read labels on food, and then trial and error on the details until you get the results you want. There’s no shortcut for this. If you have no idea where to start, the repeated advice to see a doctor is a good place to do so.
I know, but real people searching for information may read the thread too.