slow gain and weight loss

hello, my son does not gain wait very easy and he continues to loose weight, i have tried many specialist and many additvies and to no avail. I am concerned for his development and all of the doctors say he is failure to thrive but to wait and see. Some other info is he is allergic to peanuts and eggs and he also does not like milk,and cream sauces or red meats.he never seems to have an appetite and also eats only small amounts of foods.
He also has a muscle disorder called mutli mini core, the dr.s say it does not come into play and when they have weight issues they are usually being overweight. So I am stumped as what to do?

[Renee Radenberg]

Both his weight and height are just below the 5th percentile for his age. It is important that whatever food your son eats, the food need to be of high nutritional value so he gets as much protein and calories as he needs. For example having a protein source each meal --- meat / fish or cheese or yogurt; with a carbohydrate --- bread, pasta, rice, cereal; and a fat ---- pat of butter or mayonnaise if you made a sandwich. Protein comes from animal and plant. From animal sources it comes from all meats, chicken, fish, beef, pork, etc.; and dairy products such as milk, yogurt, cheeses, pudding, and ice cream. From the plant world there are complete proteins such as soy products:  tofu, soy milk, soy yogurt, soy pudding, and soy ice cream. Incomplete proteins you need to combine foods such as beans and rice, pasta with vegetables, and beans with pasta. Here are some additional tips for extra calories/protein: If he likes pasta, then add meat or cream sauces to the pasta instead of plain tomato sauce or plain pasta. Add dry milk to oatmeal, mashed potatoes, gravies, creamed vegetables, and creamed soups (add additional meats to soups) for additional protein and calories. Use all fat dairy products for now until he starts gaining weight, and then start using low fat in later years. You stated he does not like milk. Have you tried flavoring the milk with chocolate or strawberry? Suggest giving him Pediasure, milkshakes (milk and ice cream blended), or yogurt smoothies (yogurt and ice cream blended) in place of milk/fluids at meals and snacks. You can add fruit to the shakes/smoothies for additional vitamins and minerals. If he does not like red meat, then give him chicken and other non-red meats. Hoped this helped you.