I don't have much in the way of "doctor-approved" approaches, but I can speak to the frustration of forcing myself to eat. I'm currently 8 months pregnant and have been pretty turned off by food for most of the duration. Something that helped me a lot (since I wasn't aiming to starve the fetus) was smoothies - highly customizable and easy to eat. It's no fun feeling like you have to force-feed yourself an entire plate of food, and I found it easier to gulp down a smoothie when I really didn't feel like eating. The nice part is that you can add whatever you like, and you can create diverse recipes to incorporate different nutrients. Just some ideas...I tried to stuff as much spinach/greenery in as possible, frozen berries, coconut milk or regular milk/yogurt if you're inclined, coconut oil/butter/ghee, egg/egg yolk if you trust your eggs, protein powder or primal fuel, grassfed gelatin, avocado, cacao powder, nut butter...the list could go on and on. Usually smoothies are equated with ZOMGFRUIT! but it's really easy to change the nutritional makeup of them and make them quite calorie-dense. Anyway, just something that helped me w/ the disinclination to eat.