1) Avoid toxic vegetable oils (i.e. canola, soybean, corn). Instead, use extra-virgin olive oil, coconut oil, butter, ghee, avocado oil (see rebeccarumsey.com/which-fats-are-safe-for-cooking to learn about smoke points).
2) Avoid factory-farmed animal products. Choose grass-fed, pasture-raised, wild or organic meat, poultry, fish and dairy products. When factory-farmed animal products are your only option for a particular meal, make it vegetarian.
3) Avoid genetically modified foods (GMOs). GMOs are connected to a slew of health issues, including allergies and even organ failure! The top offenders are corn (88% of corn in the US is genetically modified), soy (93% of soy in the US is genetically modified) and canola oil (90% of canola oil in the US is genetically modified).
4) Replace artificial and refined sugars with naturally processed stevia, xylitol (if tolerated) and small amounts of raw honey.