The present invention relates to methods for the prevention and treatment of chronic inflammatory diseases, cancer, and involuntary weight loss. In the practice of the present invention patients are enterally administered HMB alone or alternatively in combination with eicosapentaenoic (20:5 .omega.-3), FOS, carnitine and mixtures thereof. HMB may be added to food products comprising a source of amino-nitrogen enriched with large neutral amino acids such as leucine, isoleucine, valine, tyrosine, threonine and phenylalanine and substantially lacking in free amino acids.