Fortisip Compact Protein - Strawberry (4 x 125ml). Fortisip Compact Protein is a high energy (2.4kcal/ml), high protein (18g protein/125ml bottle), ready to drink, milkshake style nutritional supplement, for the dietary management of disease related malnutrition.. Fortisip Compact Protein can be used to supplement the diet of patients unable to meet their nutritional requirements from other foods.