Summer Heat Wave or Not, We Need to Stay Hydrated after WLS!

Article By: Maria Tucker, MPH, RDN, LDN, CDCES

Maria Tucker is a Registered Dietitian and Certified Diabetes Educator with over 20 years of experience assisting patients with diabetes, obesity, and nutrition-related conditions. Maria is also the Founder of, a site dedicated to healthy recipes and kitchen shortcuts.

Water is the largest single component of the human body. It has long been established that the human body is about 50 to70% water. The Centers for Disease Control and Prevention (CDC) lists a few of the many benefits of drinking water, including maintaining normal body temperature, lubricating and cushioning joints, protecting the spinal cord and other sensitive tissues, and getting rid of bodily waste through sweat, urination, and bowel movements. However, the CDC also reported that in 2015-2018, US adults drank an average of only about 44 ounces of plain water. How much water should one drink? While there is no definite recommendation for how much plain water one should drink, recommendations for total water intake exist. In 2011, the Food and Nutrition Board, Institutes of Medicine, National Academies published the recommended Adequate Intake or AI for total water for different life stage groups, stating that males, aged 19 to 70 years or older should drink an average of 3.7 liters or 123 ounces per day. For females of the same age group, it was recommended that their average total water intake should be 2.7 liters or 90 ounces per day.

Several factors can affect your fluid intake needs, including age, gender, environmental factors, as well as medical conditions or illnesses. What about after bariatric surgery? Does the recommendation change? Is plain water the best beverage for maintaining good hydration? The American Society for Metabolic and Bariatric Surgery (ASMBS) published 2019 updated guidelines for post-operative care of the bariatric surgery patient in 2020, showing varying recommendations for fluid intake post-surgery, with the Academy of Nutrition recommending 48-64 ounces of fluids per day, UpToDate recommending consuming adequate fluids to prevent dehydration, and the Enhanced Recovery After Surgery Society recommending fluid intake of greater than 1.5 liters daily. Bariatric surgery centers can also have varying recommendations for fluid intake post-surgery; however, most of these centers recommend a minimum intake of 64 ounces of total fluids per day, at least during the first few months after surgery. As patients are able to tolerate more fluids, fluid intake recommendations can be increased and personalized to meet individual needs with the assistance of the Registered Dietitian.

Dehydration, has been defined as a condition caused by loss of excess amounts of fluids from the body. This can occur when you lose more water than you drink and can lead to negative consequences if left untreated. Immediately post-surgery, patients experience difficulty maintaining adequate fluid status due to nausea, vomiting, diarrhea as well as lack of thirst cues, leading to inadequate fluid intake. Warning signs of dehydration range from thirst, dry lips and mouth with mild dehydration to dizziness or lightheadedness, confusion, lethargy, and rapid or weak pulse with moderate to severe dehydration.

What beverages are recommended for bariatric surgery patients to drink after surgery? Most bariatric surgery programs recommend water as the main beverage to drink post-surgery. Electrolyte waters, containing sodium and potassium and even magnesium, may also be recommended to enhance fluid balance. Imagine yourself eating really salty food, such as salted nuts or beef jerky. Remember how you got thirsty afterwards? That’s your body trying to balance your fluid status by triggering thirst to make you drink more water. The Academy of Nutrition recommends using chicken or beef broth (which contains a good amount of sodium) post-surgery to help alleviate dizziness or lightheadedness. Sugar-free flavor-enhanced waters and decaffeinated coffee and tea are examples of appropriate beverages to drink after bariatric surgery. Carbonated beverages, both sugar-sweetened and sugar-free are not recommended after bariatric surgery since the carbonation can contribute to feeling full, nausea, bloating, and abdominal distention which can lead to a decreased desire to eat. Caffeinated beverages are typically not recommended due to its effects on sleep and according to some studies, its effects on increasing urination and water loss. Alcoholic beverages are also not recommended, at least for 12 months after surgery.

Whatever beverage you prefer to drink, it is important to monitor yourself for signs of dehydration and track how much fluid you are drinking daily. Set alarms to remind you to drink, if needed. Follow the guidelines of not drinking for 30 minutes before eating and waiting to drink 30 minutes after eating. Not drinking before eating will prevent feeling too full to eat, while not drinking until 30 minutes after eating prevents feeling hungry too soon after the last meal or snack and minimizes the risk of bloating, gas, and diarrhea.

If you are unsure about your hydration needs or what beverages to drink or avoid, remember to reach out to your Registered Dietitian!

BariMelts provides general recommendations, not to be construed as medical advice. Please consult your doctor.

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