Systems for controlling obesity utilize a number of space occupiers positioned in the stomach to reduce the effective volume of the stomach. Such arrangements provides sufficient stomach volume consumption to induce weight loss, but enable use of space occupiers that are proportioned to minimize the threat of obstruction even if they should migrate into the intestine. In general, numerous small volume space occupiers are placed in the stomach such that the total volume equals or exceeds the single volume of prior art single unit space occupiers. However, each individual space occupier is proportioned so that it will pass without obstruction if it moves into the intestine.