The SlimFast Snack Bar contains just 99 calories and is a chocolate flavoured nougat bar with crisped cereal, dark chocolate pieces coated in milk chocolate to create its tasty flavour. The bar is perfect for on the go or can be enjoyed as a snack at home. Slim Fast Double Choc Snack Bars are a quick, chocolate flavoured nougat bar with crisped cereal and dark chocolate pieces coated in milk chocolate that can be enjoyed as part of the Slim Fast 3. 2.1 Plan. With just 99 calories per portion, they make the perfect snack on the go or to be enjoyed at home.