[Prin]

I think the quantity might be so much that this doggy just can't get hungry enough to fit it all in... You might have to switch to a better, more rich food, so she eats less but gets the right amount of calories.

When you have things like brewer's rice and corn (at least in the One, it's corn gluten meal- more useful than corn or cornmeal), the food is boosted with less useful calories, so the doggy ends up having to eat a larger quantity.

Also, when the first ingredient is "Chicken", the weight includes the water, which ends up being removed during cooking anyway. The dried chicken probably ends up actually weighing less than the next grain ingredient. Foods with Chicken Meal or Salmon meal, etc as their first ingredient are usually better. More of the weight is actually meat!

Compare these three to Purina One:
Here is Purina One large breed Puppy's first few ingredients:

Chicken, corn gluten meal, brewers rice, poultry by-product meal (natural source of glucosamine), whole grain wheat, whole grain corn, beef tallow preserved with mixed-tocopherols (source of Vitamin E), pea fiber, fish meal, natural flavor, chicken cartilage (natural source of glucosamine), egg product, hydrolyzed sunflower oil [...]

Solid Gold Wolf Cub Ingredients (the whole list): Wolf Cub

Bison | Salmon Meal | Brown Rice | Millet | Cracked Pearled Barley | Rice Bran | Canola Oil | Flaxseed Oil | Garlic | Amaranth | Blueberries | Yucca Schidigera Extract | Taurine | Carotene | Choline Chloride | Vitamin E Supplement | Iron Proteinate | Zinc Proteinate | Copper Proteinate | Manganese Proteinate | Potassium Iodide | Thiamine Mononitrate | Ascorbic Acid | Vitamin A Supplement | Biotin | Calcium Panthothenate | Selenomethionine | Pyridoxine Hydrochloride | Vitamin B12 Supplement | Riboflavin | Vitamin D Supplement | Folic Acid |

Merrick Puppy Plate (the first few): Merrick Puppy plate site

Turkey, Chicken Meal, Chicken, Oatmeal, Whole Barley, Duck, Whole Brown Rice, Chicken Fat (preserved with mixed tocopherols – a source of Vitamin E and Ascorbic Acid, a source of Vitamin C), Potatoes, Carrots, Peas, Natural Dried Chicken Liver, Whole Apples, Dicalcium Phosphate, Calcium Carbonate, Potassium Chloride, Lysine, Guar Gum, Salt, Choline Chloride, Zinc Amino Acid Complex, Whole Blueberries, Yucca Schidigera Extract, Whole Clove Garlic, Dried Chicken, Chicory Root, Marigold Extract, Lactobacillus Plantarum [...]

Wellness Super5Mix Puppy (partial list): Wellness Super5Mix Puppy

Deboned Chicken, Salmon Meal, Menhaden Fish Meal, Oatmeal, Barley Flour, Ground Brown Rice, Canola Oil (preserved with Mixed Tocopherols), Tomatoes, Flaxseed, Peas, Carrots, Whole Sweet Potatoes, Bananas, Whole Apples, Whole Pears, Garlic [...]

I don't know what your budget is, but I think if you're willing to pay for 4.5 cups of Purina One, you won't mind paying the same but feeding maybe 3 cups a day instead? (and you'll end up with a super healthy doggy to boot!)