The best response to the patient's statement would be: "Fats help you stay warm and keep your brain working."
This response highlights the importance of healthy fats in the diet and provides a more balanced perspective. It’s essential to educate the patient that while some fats can be harmful, healthy fats are crucial for overall health, including brain function and maintaining body temperature. Additionally, it's a good opportunity to discuss the importance of balance in the diet rather than completely cutting out a macronutrient.