The present invention relates to methods of managing weight, and treating overweight or obesity and treating or preventing diabetes in a subject in need thereof. In one embodiment, the method comprises the steps of (a) orally administering to the subject from about 0.7 g to about 4 g of crosslinked carboxymethylcellulose; and (b) orally administering to the subject at least about 100 mL of water per gram of crosslinked carboxymethylcellulose. Steps (a) and (b) are conducted prior to or with at least one meal per day.