The present invention provides a polysaccharide rich composition comprising beta-glucan, chitin and chitosan, extracted from the cell wall of Saccharomyces cerevisiae from the by-product biomass resulting from a brewing process, the process for obtaining it and the uses thereof. The composition exerts, among other biofunctionalities, a selective fat binding effect so it is useful in the prevention and/or treatment of a disorder such as overweight, obesity, hypercholesterolemia, hypertriglyceridemia, blood hypertension and cardiovascular disorders. It can be formulated as edible, pharmaceutical or a veterinary product.