A bariatric device (10) for weight loss, comprising a. an element of the lower stomach (26) that has a wall comprising a light, that has an inner surface, an outer contact surface comprising a truncated cone of inclined wall adapted to fit the walls (20) of the middle to lower stomach , and in which the lower stomach element is constructed with elastic material (50) that can be folded for placement and recovered to maintain its shape for operation, and sized to prevent the lower stomach element (26) from being placed in contact with or pass through the pylorus (18) characterized in that it additionally comprises b. a positioning element (25, 27, 51, 52) with proximal and distal ends, comprising two closed loops (51, 52) arranged in different planes, in which the distal ends of the loops (51, 52) are coupled with the lower stomach element (26), and the proximal ends are adapted to fit in the upper stomach, in which the positioning element is constructed with elastic material so that the proximal end can be brought into contact with the upper stomach to maintain the relative position of the lower stomach element (26) to make the lower stomach element (26) have at least intermittent contact with the middle to lower stomach, and c. a restriction element (35, 37, 46, 47, 77, 107) coupled with the lower stomach element (26).Un dispositivo bariátrico (10) para la pérdida de peso, que comprende a. un elemento del estómago inferior (26) que tiene una pared que comprende una luz, que tiene una superficie interior, una superficie de contacto exterior que comprende un cono truncado de pared inclinada adaptado para ajustarse a las paredes (20) del estómago medio a inferior, y en el que el elemento del estómago inferior está construido con material elástico (50) que puede plegarse para la colocación y recuperarse para mantener su forma para el funcionamiento, y dimensionado para impedir que el elemento del estómago inferior (26) se ponga en contacto con o pase a través del píloro
