Gastric bypass is a major operation, even if it is of the minimally invasive kind. It is important to adhere strictly to your doctor's guidelines when it comes to the food and drinks that must be avoided once the procedure is completed, especially during the period immediately after your operation. 

Avoiding caffeine after gastric bypass surgery is a common medical guideline. Here are some reasons why.

Caffeine is a Stimulant and Diuretic

Two effects of caffeine that are not tolerated well by post-gastric bypass operation patients are that it temporarily increases the heart rate, and  that it acts as a diuretic. The main source of nutrition of patients who have just undergone the gastric bypass procedure is liquids, and because of the diuretic effect of caffeine, the liquids will be flushed out immediately, leaving you feeling dehydrated and weak. Thus, it is recommended that the intake of caffeine be limited to a maximum of 300 mg.   (Schauer, P. R, 2007)

Caffeine Makes You Feel Hungry

One of the goals of the gastric bypass operation is to ultimately reduce your food intake, even after you have lost a significant amount of weight. By taking large amounts of caffeine right after your operation, you become susceptible to feeling hungry more often because of caffeine's diuretic and thermogenic effects. (Dr. Andrade, tc.umn.edu )

Caffeine Irritates the Stomach Pouch

Another reason why liquids that contain caffeine are not recommended after the gastric bypass operation is that it can cause irritation of the stomach pouch, which is extremely sensitive right after the said operation.

Preventing Caffeine Withdrawal Symptoms

Because of the absence of caffeine in your body after a gastric bypass operation, you may experience caffeine withdrawal headaches, especially if prior to your operation, you were highly dependent on caffeine for energy. To avoid such an occurrence, gradually decrease your caffeine intake months before your gastric bypass operation, so as not to shock your system.