It is best not to drink the first glass of water in the morning. Most carbonated drinks such as soda and cola contain citric acid, which will accelerate the excretion of calcium in metabolism and reduce the calcium content in blood. Long-term drinking will lead to calcium deficiency. Other drinks have diuretic effect. Drinking them in the morning can not only effectively replenish the water that the body lacks, but also increase the body's demand for water, thus causing water shortage in the body.