Each bottle of Ensure Pre-Surgery Clear Carbohydrate Drink from the #1 doctor-recommended brand Ensure is formulated with carbohydrates and antioxidants to help your body prepare for and recover from surgery. Ensure Pre-Surgery is specially designed to help reduce insulin resistance after surgery and improve patient outcomes. It is designed to be consumed up to 2 hours before surgery. Every drink has: 50 grams carbohydrates Antioxidants: zinc selenium 200 calories Refreshing strawberry flavor.