When we think of feeding our dogs and cats, we imagine wholesome meats, fresh vegetables, and nutrient-rich foods. But hidden deep in many pet food labels is something far less appetizing: recycled restaurant grease. Yes, the same oil used to fry French fries and chicken nuggets in fast-food joints can end up in your pet’s bowl.
What Exactly Is Recycled Grease?
The industry calls it yellow grease or used cooking oil. Restaurants and food processors collect their fryer oil after it’s been used over and over at high heat. Instead of discarding it, the oil is picked up, filtered, and sold to rendering plants. From there, it’s reprocessed into “feed-grade fat” — which can legally be used in livestock feed and pet food [1][2].
On paper, it’s a win-win: restaurants offload waste, renderers make a profit, and pet food companies get a cheap fat source. But is it really a win for your pet?
The Problems With Recycled Grease
1. Oxidation and Rancidity
Cooking oil breaks down under repeated heating, forming harmful oxidation byproducts and even trans fats. These degraded oils don’t provide the same nutrition as fresh fats. Instead, they may promote inflammation and stress in the body over time [3][5].
2. Contaminants
Think about what goes into a restaurant fryer: breading, burnt bits of food, sometimes even cleaning chemicals. Studies show that yellow grease can carry heavy metals, residues, and microbial contamination if it’s not handled properly [6]. Yet once it’s blended into “animal fat,” it hides behind vague ingredient labels.
3. Zero Transparency
That “animal fat” or “meat fat” listed on a kibble bag? There’s a good chance it’s not from a freshly rendered meat source at all, but a mixture of used cooking oils. Pet parents have no way of knowing, because regulations don’t require brands to specify the origin [1][2].
Why It’s Used Anyway
There’s one clear reason: cost. Recycled grease is far cheaper than sourcing fresh, species-specific fats like chicken fat or salmon oil. For companies selling kibble, it’s an easy way to boost palatability (dogs do love the taste of grease) while keeping margins high [4].
But “cheap and tasty” doesn’t mean safe or nutritious — and most owners have no idea they’re paying for waste oil instead of real food.
Is It Legal? Absolutely.
The Association of American Feed Control Officials (AAFCO) defines and allows the use of “Yellow Grease, Feed Grade” in animal feeds, including pet food [1][2]. As long as the oil meets loose standards for moisture and impurities, it passes.
Legal approval only guarantees that recycled grease meets the lowest possible standard — not that it offers any real nutritional value or safety for pets [6].
What Pet Parents Can Do
- Read Labels Critically: Be cautious of generic terms like “animal fat,” “poultry fat,” or “meat and bone meal fat.” Transparent brands will tell you exactly where their fats come from.
- Demand Better: If you’re paying premium prices, you should expect premium ingredients — not waste oil. Ask brands directly about their fat sourcing. ASK FOR DOCUMENTATION. We've seen companies SAY good things about their products, but then when asked for proof, they can't produce it
- Choose Fresh, Named Fats: Look for foods that specify “chicken fat,” “beef tallow,” or “salmon oil” rather than vague “animal fat” or “fat blend.”
- Consider Fresh or Raw Options: Many smaller, fresh-feeding brands reject feed-grade fats altogether, sourcing their oils the same way human food companies do.
Final Word
Recycled restaurant grease is another secret within the pet food industry. It’s legal, it’s profitable, and it’s hiding in plain sight.
As pet parents, the more we question — and the more we demand transparency — the harder it becomes for the industry to keep sweeping ingredients like this under the rug.
References
- AAFCO Official Publication 2024, Chapter 6: Definitions – “Yellow Grease, Feed Grade.” AAFCO.org (PDF)
- “AAFCO Definition of Yellow Grease (Feed Grade).” Solutions Pet Products (PDF), 2025. Link
- Layn Nutrition. “Oxidation: A Permanent Phenomenon in Pet Food.” Petfood Industry White Paper (2021). PDF
- Kemin Industries. “Oxidation in Pet Food & Palatability.” Kemin Petfood Solutions (accessed 2025). Kemin.com
- Pacheco et al. “Oxidative status of rendered protein meals and its influence on protein quality.” Animal Feed Science and Technology, 221 (2016): 321–330. PubMed Central
- Kent, Chelsea. “What’s Hiding Within That Ingredient Label? A Possible Under-Evaluated Nutritional Contributor to DCM in Pets.” Solutions Pet Products Blog (2024). Link
