I go to a personal trainer who has taught me the importance of exercise and nutrition went from 210 down to 150

To be honest, I'd only be going to a nutritionist if the weight gain was for a reason other than HIV and the meds. They don't know why we are gaining weight, or they would have told us. I'd find a comfortable fat burning regime like keto or intermittent fasting. Those work. Especially if HIV or the meds are causing some sort of insulin resistance. It takes a lot of experimentation, but you have to get to the bottom of what's "seems" to cause it. Then work from there.
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Exercise

Cut carbs..eat proteins...