"Plenty of people jump right in, thinking all they have to do is cut carbs and increase fat. All of a sudden, they hit a wall and get 'keto flu.' They feel tired, lethargic, and experience headaches," Wittrock says. "The primary reason they get these symptoms is lack of the three primary electrolytes: sodium, potassium, and magnesium. If you're deficient in any of these, you'll suffer mentally and physically. This is the single biggest reason people fail on the keto diet."
Insulin is a hormone that lets your body use or store sugar as fuel. Ketogenic diets make you burn through this fuel quickly, so you don’t need to store it. This means your body needs -- and makes -- less insulin. Those lower levels may help protect you against some kinds of cancer or even slow the growth of cancer cells. More research is needed on this, though.
Avocados are loaded with heart-healthy monounsaturated fats, as well as fiber, which keeps your digestion running smoothly. This fruit can also help replenish electrolytes in the body. For example, a cup of avocado delivers 975 milligrams of potassium, a mineral that regulates fluid balance in the body. That’s extra important when you're on a very low-carb diet—this type of eating causes your body to excrete water and electrolytes, which can lead to dehydration, dizziness, and fainting.