Some kinds of fat can make OA pain worse and some can make it better. If you eat a lot of red meat and fried food, you’re loading up on Omega-6 fatty acids. They promote inflammation, which promotes pain. If you eat walnuts and cold-water fish such as salmon or tuna instead, you'll get Omega-3s, which fight inflammation.
In the typical American diet, the ratio of Omega-6s to Omega-3s is at least 16 to 1. To reduce inflammation it should be 3 to 1.