This is one of the biggest causes of water retention: eating too much salt. "Whenever we indulge too much in sodium rich foods, it causes your body to hold extra fluid in cells that leads to water weight," Cheryl said. "Assess your diet and stop eating overly salty foods that are usually found in a box, bag, or can. Think: chips, pretzels, canned soups, or TV dinners." If you wake up puffy and bloated, try and avoid these overly salty foods for the next couple days.