The symptoms of keto flu are headaches, body aches, cravings, brain fog and fatigue. Well, just think about what you’re trying to do. You’re converting your ENTIRE cellular machinery to fat burning. What you need to do to avoid and heal the keto flu is get more electrolytes and more B vitamins. These are the cofactors that help in developing the machinery to burn fat effectively without draining your body. For the B vitamins, try nutritional yeast. However, nutritional yeast does not have B5—so you may have to take a B5 supplement. I recommend my electrolyte powder. It has 1,000 mgs of potassium and will help you get to that 4,700 mgs you need to create this machinery to burn fat faster and get into ketosis!
For another science-based resource on ketogenic diets, I highly recommend visiting the site that Raphael Sirtoli and his team over at Break Nutrition have put together. They have good content about low carb and ketogenic diets, and they offer more information on how to kick-start a ketogenic diet, measure your ketones and there's a great post on the benefits of ketogenic diets for inflammation.