Canidae is another great brand. We use the chicken formula, but their website says they have a Beef/Fish formula, and it's ingredients appear below. You can check their website for merchants who sell this brand. We get it locally from a veterinarian. Our dogs love it.
As for protein causing dogs to store fat, I'm not positive about that one. It's been forever since I studied that sort of thing, but I thought protein was the one thing bodies could not convert to fat. At any rate, most Canidae products are designed for dogs of any age.
CANIDAE All Natural Ingredients
Beef, ocean fish meal, oatmeal, beef meal, brown rice, white rice, rice bran, peas, cracked pearled barley, millet, canola oil, tomato pomace, natural flavor, flaxseed meal, choline chloride, sun cured alfalfa meal, inulin (from chicory root), lecithin, sage extract, cranberries, beta carotene, rosemary extract, sunflower oil, yucca schidigera extract, dried enterococcus faecium, dried lactobacillus acidophilus fermentation product, dried aspergillus oryzae fermentation extract, dried bacillus subtilis fermentation extract, saccharomyces cerevisiae fermentation solubles, vitamin E supplement, iron proteinate, zinc proteinate, copper proteinate, ferrous sulfate, zinc sulfate, copper sulfate, potassium iodide, thiamine mononitrate, manganese proteinate, manganous oxide, ascorbic acid, vitamin A supplement, biotin, calcium pantothenate, manganese sulfate, sodium selenite, pyridoxine hydrochloride (vitamin B6), vitamin B12 supplement, riboflavin, vitamin D supplement, folic acid, cobalt proteinate, organic selenium, papaya, pineapple.