Drinking a 16-ounce glass of cold water before every meal may decrease calories eaten
As long as I can remember, I have recommended a full glass of water before each meal. Since your body is made up of up to 60% water by volume, it only makes sense that our bodies would operate more efficiently if you are well hydrated, but does it help you feel full and eat less food. To me, filling up on water instead of food to decrease your appetite just makes sense. The science supporting drinking the water weight loss theory was sparse until about 2008 when a new study showed that drinking a single 12-16 ounce bottle of water before each meal may decrease calorie intake. In more recent studies from 2012, the research has proven that water, along with fruits and vegetables, can assist with weight loss maintenance. At this stage, more research was a need to confirm that water will decreases calories consumed.
A more recent study from 2015 finally confirmed the results of the 2008 research on water before meals. This study published in Obesity showed that drinking water before meals can help weight loss. For nearly 3 months, just over 40 obese subjects drank approximately two cups of water and just over 40 were told to imagined feeling full before eating their daily meals. Participants who drank water before each meal lost nearly six pounds more on the average compared to the control group.
The bottom line: Water makes you feel full. It is suspected that water may have led subjects to feel full and resulted in fewer calories consumed. For more on water: 21 Fool Proof Ways to Increase Your Water Intake, Research Proven Weight Loss: Drink Water, and One Bottle of Water Can Induce Weight Loss.