What, Why, and How

WHAT

Avoid:

Reduces/Avoid as much as possible:

Reduce (for metabolic conditions):

Eat:

Nutrient dense foods like meats, fish, eggs, dairy – Grass-fed, wild caught if possible and organic as much as possible
Green vegetables – Organic preferred
Butter, coconut oil, lard, olive oil
Real foods made at home to know what is in it and how it is made

Vegetable and seed oils are high in omega6 compare to omega3 – Omega6:omega3 should be no more than 4:1, most seed oils like canola, soy, sunflower, etc. are high in omega6 and that makes them inflammatory. They are also highly processed and many chemicals used to extract the oil. They used to be used as industrial oils before modified and introduced into human diet in the 1970s.
High Fructose Corn Syrup (HFCS) that also was made in the laboratory and introduced into our diet in the 1970s, is used in most soft drinks and packaged/processed foods. High fructose consumption, specially the free form in HFCS has been linked to many metabolic, autoimmune, inflammatory diseases such as diabetes, fatty liver disease, Irritable Bowel Disease like crohn’s disease and ulcerative colitis (IBD) and many cancers.
Also this:

Ignore most of mainstream health information you find from the usual sources like Harvard Health and WebMD.
Research and learn the science behind food, what body does with it and in response to it that can both cause or help treat metabolic, inflammatory, autoimmune diseases
Having done enough research, you come to form an overall understanding and philosophy to guide you through.
Clear your home from unhealthy foods and drinks and replace with the healthy alternatives.
Variety is not important, regular main sources of healthy nutrients is.
Eat when hungry, consider intermittent fasting a few times a week by eating later in the day to allow about 14 hours of not eating.
Start the day with low carb foods, coffee & cream, cheese, eggs, nuts, berries, etc. This will discourage insulin production as it is produced in response to sugar and carbohydrate consumption and will reduce craving and snacking during the day.
You should not need to eat more than twice a day if on a low carb diet.
Take long walk in the sun without sunscreen for vitamin D, exercise and eyes health.
Low light at night and before sleeping, adequate sleep of at least 7-8 hours.