Fruit is high in carbs and fructose. Fructose, even from natural fruit, puts a serious metabolic load on your liver if eaten in large amounts. Berries are the lowest in carbohydrate, so if you have to have something sweet, you could eat 1 or 2 strawberries on a ketogenic diet, but the fructose might halt ketosis. Below you can see a list of fruits you should watch out for.