There is some indication that insulin resistance begins long before blood glucose rises enough to alert your doctor to a diagnosis of diabetes, so you are wise to be concerned. The only real test for insulin resistance at your stage is an oral glucose tolerance test, which is tedious and expensive, because it involves taking a dose of glucose and then periodically measuring your insulin response over a couple of hours. Unfortunately, this cannot be done at home, since the insulin assay involves radioactivity and an expensive machine. (There are people working on a home insulin test, but it is proving quite a challenge.)
The key to a ketogenic diet is to limit your carbohydrate intake to a level low enough to avoid stimulating an insulin response. Elevated blood glucose and insulin levels are dangerous, for a number of reasons. The exact level at which blood glucose stimulates insulin seems to vary from person to person, and the 20 g/day of carbohydrate limit you see recommended on these forums is arbitrary. But it will get you into ketosis, and once you become fat-adapted, you will be in a position to see if your body can handle more carbohydrate than that, as it most likely can.
The vegetables we recommend eating on a well-formulated ketogenic diet are leafy greens, and cruciferous vegetables such as broccoli and cauliflower. Cucumber, tomato, and others that are mostly water are semi-okay, you just need to watch their carb content. Fruits are also iffy, except the savory ones, such as avocado, and the “vegetables” that are really fruits. Berries tend to be high in fiber, so that offsets their carb count (“net carbs” = total carbs - fiber; “total carbs” = digestible carbs + fiber). We also recommend staying away from sugar as much as possible, because it has deleterious effects on the liver as well as raising insulin.
If you go keto, you can expect a period of adaptation that may last as long as two months. Your exercise performance will drop, until your muscles adapt to using fat instead of glucose for energy. You may also experience flu-like symptoms (called “Atkins flu” or “keto flu”), but these are the result of a sodium deficiency and are completely avoidable if you take care to increase your salt intake (the kidneys excrete sodium more rapidly in the absence of dietary carbohydrate). Once you have become fat-adapted, your performance will return to and possibly exceed its pre-keto level.
You may also have trouble with what we call “hidden carbs,” and one solution is to avoid processed foods and concentrate on whole food: meat, fresh veg, that sort of thing. You will also need to replace the missing calories from not eating carbohydrate with calories from fat, since fat stimulates very little insulin response, and is therefore a safe source of energy. Eat mostly saturated and monounsaturated fats (butter, ghee, lard, tallow, bacon grease, and fruit oils—avocado, coconut, and olive), and eat fatty cuts of meat, cheese, heavy cream (assuming dairy is okay in your diet).
There’s a lot more in the way of healthy eating, but cutting carbohydrate is the key to all the rest.
Do let us know how you’re getting on. I’d love to know how things turn out for you. Welcome to the forums!
