Inclusion Criteria:  weight > 75 Kg absence of previous diet therapy attempts no fluctuation of at least 3 kg in the previous 3 months Beck Depression Inventory score < 20 pt Binge Eating Scale score < 27 pt  Exclusion Criteria:  allergy to shellfish pregnancy or breast feeding presence of cardiopathies, nephropathies, liver diseases, bronchopneumopathies, haemopathies, dermopathies, chronic-degenerative diseases of the Central Nervous System presence of active peptic ulcer, ulcerative colitis, Crohn's disease, celiac disease, inflammatory bowel disease symptomatic cholelithiasis previous or current neoplasms epilepsy obesity secondary to endocrinopathies or genetic syndromes significant motor disability or mental retardation major depressive disorder, bulimia, panic disorder, obsessive-compulsive disorder, post-traumatic stress disorder, bipolar disorder (I or II), schizophrenia previous history or current diagnosis of drug abuse or alcoholism changing in smoking habits or quitting smoking in the last 6 months current use or in the last 3 months of psychoactive drugs or current use or in the last 12 months of drugs affecting body weight or appetite