Hang in there, and be firm. Don't even buy grahm crackers and then you wont be tempted to serve them. Don't give him milk or juices of any kind, with meals, or in between. Some toddlers use both of these substances as meals. You can serve it after his meal. milk fills the belly, and fruit juice, which is all sugar, supresses the appetite. Sugar of all kinds, including processed carbs like crackers and such, will modify that craving for good food, change the kids taste buds, and reduce his natural hunger. Veggies and fruit taste MUCH better when you are hungry.
Ever heard of chia seed? it says its better than flax. 64% omega 3 oil (the good oil found in fish),more calcium than 2% milk, more antioxidants than blueberries, easily digestible protien, more fiber than bran, and gluten free.The oil in it helps absorb vit A,D,E, and k. It turns gelatinous in liquid, so you can add it to pancakes, smoothies, oatmeal, pb and J, puddings,cakes,etc. I get mine from nutsonline.com. There are a ton of distributors online and you can probably find it in the health food store.
Not enough vitamin A, magnesium, and zinc can all cause a lack of appetite. So if you can someohow increase these nutrients you might see a better eater. Also, if there is carb prefrences give more Chromium in diet and it will reduce the cravings. The best way to get these vits is in food because the foods already have the co-vitamins in them that help you absorb them.
foods:
Chromium=tomatoe,romaine,oysters,liver,raw nuts,green bean.
Magnesium=raw pumkin seed,chinook salmon,halibut,broccoli
zinc=peas,shrimp,lowfat yogurt,beef tenderloin
if you dont have fresh foods, try feeding frozen. (canned veggies are just yuk,yuk,yuk.) how about frozen peas. if you freeze quartered grapes, and serve them like that, those are yummy. I put a tablespoon or two of soy sauce in my steaming water when I make brocoli. It turns brocoli haters into brocoli eaters. (toddlers have more sensitive tastebuds and may need much less) Try using coconut oil to stir fry veggies, and add very small amount of soy at the end and stir it up. To get the best bang of nutrients for your buck when buying fresh, buy organic.
Lastly, you could try to give him Cod Liver Oil. Walmart has an orange flavored one. It is the highest source of vit A you can get and good supply of vit D. It's an excellent superfood. Vitamin A specifically helps the thymus gland (immune system) mucosal tissues(reduce the colds, ear problems, etc) bones, skin,eyes and growth.