Exercise, particularly high-intensity exercise, tends to speed up the transition phase because it helps deplete glycogen stores quickly, forcing the body to rely more on fat. Additionally, starting the transition with fasting or intermittent fasting can rapidly increase ketone production.
The ill feeling that may occur in the first few days after initiating a ketogenic diet is commonly referred to as the keto flu. Fortunately, this feeling is temporary and can be completely or partially alleviated by following a few precautionary measures. First, consider your electrolytes. A deficiency in sodium, potassium, or calcium could make you feel sick. Second, consider your hydration level. It’s easy to get dehydrated at the beginning of the ketogenic diet. Third, consider your fiber intake. If you’re not getting enough fiber, you could become constipated. The takeaway: replenish your electrolytes, drink a lot of water, and make sure you’re getting enough fiber.
Taking ketone supplements without lowering carbohydrate intake will not likely make you fully keto-adapted. It is unknown whether taking these supplements long-term can lead to certain changes that typically occur with keto-adaptation (such as an enhanced capacity to allow ketones to enter tissues to be used for fuel by increasing the number of ketone transporter proteins), but in order to be fully keto-adapted, some degree of carbohydrate restriction needs to occur.
The keto flu is a constellation of symptoms that can occur when you’re adjusting to a ketogenic diet. Symptoms include a lack of mental clarity, nausea, headaches, and constipation. A well-formulated ketogenic diet that takes into account electrolytes, fiber, and hydration can help mitigate these symptoms.
When you’re keto-adapted, your body has transitioned from primarily using glucose as fuel to primarily using fat and ketones. Once accomplished, you will start to see a change in satiety, hunger, and even cognitive function/focus.