@samuel497 There are no rules to eating ketogenically, except to keep carbohydrate intake as low as you can. (On these forums, we recommend an upper limit of 20 grams a day.) The purpose is to reduce the chronically elevated insulin levels that accompany a high intake of carbohydrate.
A well-formulated ketogenic diet tends to be healthier, and not just because of ketogenesis. The healthiest food is whole, fresh, minimally-processed ingredients, but people have successfully gone keto by eating at McDonald’s. (Dr. Westman has a patient who reversed his diabetes and lost a significant amount of weight by eating there; he simply avoided the buns and the French fries.)
As far as fats are concerned, we do advise avoiding the seed oils (safflower, cotton, peanut, canola, etc.), since they are extremely high in ω-6 fatty acids, which cause systemic inflammation when eaten in quantity. The healthiest fats are butter/ghee, lard, tallow, bacon grease and the fruit oils (avocado, coconut, and olive).
Avoiding processed foods and sticking to meat, dairy, and fresh vegetables can feel more expensive at first, but two things make the cost manageable: first, as the hormones regulating appetite start to work properly again, people generally find themselves eating less and eating less frequently. Second, the health benefits can save a significant amount of money, because people need fewer doctor’s visits, so they don’t lose income from taking time off, and they aren’t paying for expensive medicines.
A simple rule of thumb is to stay away from the aisles in the middle of the supermarket, and stick to the items around the edges. These days, I primarily visit the aisles to find coffee and pork rinds (and non-food items).
Lastly, when people advise against “processed” foods we are talking primarily about snacks, breakfast cereals, instant “foods,” and the like—the sort of thing that Michael Pollan refers to as “edible food-like substances”—not about traditionally preserved meats and cheeses. Although as several commenters have posted, sugar is now finding its way into everything, so we have to be vigilant about the list of ingredients.
But check the carb count of any vegetable you want and keep your daily total under 20 grams. I even have a few tomatoes now and then, and enjoy onions and garlic a bit too.
I eat that in my strictest days as well, why not? I don’t know about the carb content in mine but it’s surely negligible. It’s proper, drier sausage from a farm I trust. It has carbs as it’s red from red pepper as every Hungarian sausage should but it’s still negligible.