What's actually in Iams?
We analyzed Iams ProActive Health Indoor Weight & Hairball Care, one of their top-selling cat formulas. The first five ingredients are chicken, corn grits, chicken by-product meal, corn gluten meal, and dried beet pulp.
Chicken as the first ingredient is a real positive for a cat food at this price point — cats are obligate carnivores, so having a named animal protein lead the formula matters. But corn grits at number two is a cheap, refined carbohydrate filler with minimal nutritional value. Chicken by-product meal at three provides concentrated protein but from lower-quality parts (organs, necks, feet). Corn gluten meal at four is the second corn-derived ingredient in the top four — a plant protein booster that inflates the protein number on the label without delivering the amino acid profile cats need. That's two corn sources in the top four positions for an obligate carnivore. Dried beet pulp at five is actually a solid inclusion — it's a prebiotic fiber that supports healthy digestion despite its unglamorous name. Shop on Amazon →
The good stuff
The functional ingredients are where Iams earns its points. Fructooligosaccharides (FOS) are a prebiotic fiber that feeds beneficial gut bacteria — a genuinely useful ingredient that many competitors at this price skip entirely. L-Carnitine supports fat metabolism, which is particularly relevant for an indoor/weight management formula targeting less active cats. Taurine supplementation is present and essential — cats can't synthesize taurine on their own, and deficiency leads to heart disease and blindness.
Rosemary extract as a natural preservative means no artificial BHA or BHT. The vitamin and mineral panel is comprehensive. And the price is genuinely accessible — Iams typically costs significantly less per pound than Hill's Science Diet or Purina Pro Plan, both of which score in the same C range.
The not-so-good stuff
Two corn ingredients in the top four is the core problem. Corn grits and corn gluten meal together make up a significant portion of this formula, and neither provides the kind of nutrition an obligate carnivore needs. The protein percentage on the label looks adequate, but a meaningful chunk of it is coming from corn gluten meal rather than chicken.
Chicken by-product meal at number three is functional but signals cost-conscious sourcing. No fish oil means no omega-3 fatty acids for skin, coat, and joint health. No probiotics (though the FOS prebiotics are a partial substitute). No fruits, vegetables, or antioxidant-rich ingredients. Powdered cellulose — wood pulp filler — appears further down the list as a hairball management tool, but it's still filler.
How it compares
Iams at C/62 now leads the vet-recommended C-tier cluster. Hill's Science Diet (C/60) sits two points lower. Purina Pro Plan (C/56) six points lower. All three C-tier cat foods share the same basic pattern: chicken first, then a wall of grain and plant protein fillers.
The real comparison is upward. Blue Buffalo (B/76) and Taste of the Wild (B/76) both score a full grade higher with meaningfully better ingredients. Wellness (B/80) leads the pack. If you can stretch the budget even slightly, the jump from C to B territory delivers a noticeably more meat-forward formula.
Read the full breakdowns in our head-to-head comparisons: Iams vs Purina ONE, Iams vs Blue Buffalo, and Rachael Ray Nutrish vs Iams.
The bottom line
Iams ProActive Health earns a C grade (62/100) from KibbleIQ. The FOS prebiotics and L-Carnitine are genuinely useful functional additions that most budget competitors don't include. But the corn-heavy formula, by-product meal, and missing omega-3s keep it firmly in average territory. If your cat is healthy and thriving on it, there's no emergency — but a modest budget increase opens the door to significantly better options in the B tier. Shop on Amazon →