Thanks to an integrative health NP this is the current plan on which I am very very slowly losing body fat yet mostly retaining muscle with my particular genetics and enzyme insufficiencies:
methylated multivitamins, no “enriched” foods, no gluten, a high potency Vitamin D in liquid form for persistent D deficiency, very minimal dairy, extra lean proteins and copious amounts of leafy greens and low GI vegetables plus at least one serving of cruciferous/sulfurothane vegetables daily, and whole foods and (gluten free) grains in a low fat, low salt, low net carbohydrate intermittent fasting + keto diet. I am using Mayo’s healthy Keto plan but customizing it to my needs because it doesn’t allow for all of my food sensitivities.
It looks like this:
Breakfast - one unflavored, unsweetened vegan protein shake made with flax meal and a fiber supplement powder for breakfast followed by unlimited herbal tea, and no more than 1 cup of weak green tea (unable to have much caffeine).

Lunch - one very large dark leafy organic greens and herbs and low GI veg salad with 1/4 c raw, unsalted nuts or seeds, 2-4 oz. Of extra lean or omega rich protein (chicken breast, cooked low/no salt lentils or beans, salmon, or another protein shake on the side) and low sodium homemade dressing of lemon juice and tahini (then omit nuts/seeds) or olive oil and fresh lemon juice, with 1-2 tsp salt free seasoning of choice.

Dinner - 4 oz. Extra lean or omega rich protein with 1-2 C of green vegetables and up to 1/4 C of cooked brown rice, quinoa, or starchy vegetable with olive oil ( if I was physically active to a certain degree).

1 serving of fresh or dried fruit. Only water-extracted non-laboratory created stevia, can’t have erythritol or other artificial sweeteners (they cause migraines, dizziness) and filling up on as much herbal tea and water as needed between meals to feel full.

This represents one half of my RMR in caloric intake, yet doing this plus being as active as the average person my age, I lose roughly 1 lb. a month of body fat, as opposed to the expected 2+ lbs. per week, so one eighth as much as I should be. There is no explanation for this.

As you can see, it is very restrictive and frankly, impractical if one ever wants to go out with friends or family or attend gatherings. It is very difficult to adhere to, and I get quite frustrated and depressed when the scale fluctuates.

My parents also have a family friend with similar intolerances and weight issues. So far we are “medical mysteries”, and she, too, has resorted to crafting her own diet to meet her needs since the experts couldn’t help her.

Note that testing is not allowed by the insurance companies, thus is not done by our medical institutions even though it would mean better health and fewer prescriptions, visits, surgeries, co-morbidities, etc. that the insurance companies would have to cover in the long run.

The current medical stance is that genes have been found to play a role in body weight and especially in the tendency toward central obesity, but probably not enough of a role to look further into it.