There are studies everywhere on the subject of weight loss mostly because it is big business. Green tea, ice cold water, calcium, red wine and soooo many other things have been linked to higher metabolism. My go to is fiber, yes plain old regular fiber. If you eat a diet high in fiber you will be healthier, have better bowel movements and eat more natural foods. Also 99% of processed foods are lacking in it. I am not saying go pounding Metamucil just increase your dietary fiber intake.