We've been pretty strictly primal at home now for over a year. Kids are 3 and 6. They are both extremely skinny for their age and as I was watching my 3 year old in the pool today I realized that my once chunky toddler has skeletal looking arms - it was kind of disturbing just how little there was to them. 3 year old is about 29 lbs, 6 year old is 38 lbs.
They eat rice/potatoes at least once a day. Lots of fruit and veggies. Meat at least 2 meals/day. I do low sugar/high fat primal baking that the kids eatonce in awhile. B'fast is usually coconut flour/almond butter pancakes made with lots of eggs (they OD'd on eggs and won't eat them plain more than once or twice a month now). The 3 year old drinks about 1 cup of whole milk/day. Snacks are cheese, pepperoni sticks, sometimes hard boiled eggs, nuts, fruit, raw veggies, popsicles (coconut milk with either dark chocolate or berries), or primal muffins or cookies. Veggies are usually pan fried in lard. When we have ribs/pork hocks the 3 year old has been known to eat big hunks of fat.
I don't think adding more fat to their diet is needed - they get PLENTY. They are quite active. I'm guessing more carbs is what they need? More rice? More potatoes? Neither will eat sweet potatoes. Any other suggestions?