There is an excellent website called “www.balanceit.com” run by the American Association of Veterinary Nutritionists. Available to owners and veterinarians.
You type in a protein and the carbohydrate of your choice, such as Turkey and rice, then some info about your pet. The website will run formulas automatically and come up with a balanced recipe for homemade diets. This is so useful for owners who can not or do not want to feed commercially made diets.
The chapter for the veterinarian requires log in with a current license number. The same information can be used to calculate a custom diet for the many different medical problems that require a special diet. Ask your vet to try this site next time your overweight allergic dog needs a special diet and make it yourself at home.