Abstract: A human use dietary product composition to reduce fat body mass without substantially reducing lean body mass, in obese or overweight patients includes a protein component and an amino acid additional component, the additional component containing a determined amount of lysine and/or tryptophan such that on the whole lysine and tryptophan in the composition have a weight ratio set between 2.5 and 4. To cope with typical protein-based diets drawbacks, the composition further includes an amino acid additional component with an amino acid selected from the group including lysine and/or tryptophan, in an amount such that on the whole the lysine and tryptophan in the composition have a weight ratio set between 2.5 and 4. The composition further contains a component that may be a polysaccharide or an enzyme, or a combination thereof. The enzyme may be ?-Galactosidase, Lactase, an enzyme having a flatulence reducing action, or a combination thereof.