Is Fructose Keto?
Fructose is not keto-friendly because it is a high-glycemic sweetener that may kick you out of ketosis even with small amounts.
Fructose has a high glycemic index of 25 which may cause your blood sugar level to spike.
It is also linked to an increased risk of chronic diseases such as obesity, cardiovascular disease, and diabetes.
As an alternative, you may use non-glycemic and non-caloric sweeteners such as stevia, monk fruit, and erythritol.
Too Much Carbs!
Fructose should be avoided on keto because it is very high in net carbs (10g of net carbs per 10g serving).
It is important to limit your net carb consumption to 20g - 30g per day to stay in ketosis. You can calculate your ideal daily net carb allowance by using this keto macros calculator.
As an alternative, you may look for other sweeteners that are low in net carbs.