The climate in Houston is humid and subtropical. July and August are typically unbearable. This year, however, July was the hottest month ever since record keeping began a century ago. With soaring heat indices, water losses increase and staying hydrated becomes a challenge. The reason being that water homeostasis is not perfect and dehydration commonly occurs. By the time you are thirsty, you have lost around 1% of your body water and you are already dehydrated.

The American Journal of Clinical Nutrition has recently published a study titled “Minor degree of hypohydration adversely influences cognition: a mediator analysis”. 101 volunteers were subjected to a temperature of 30 degrees Celsius for 4 hours and randomly divided into two groups. The first group drank 300 ml of water during the study period and the second group did not consume any fluids. Episodic memory, focused attention, mood and the perceived difficulty of tasks were measured on 3 occasions. The authors found that drinking water improved cognitive function like memory and focused attention even with less than 1% body water loss. Thirst was associated with poorer memory and increased thirst was associated with a decline in subjective energy and increased anxiety and depression.

The value of this study is that hypohydration, or loosing less than 1% of body water, a common daily occurrence in Houston, affects cognitive functions. Hypohydration is particularly common among our bariatric patient population especially in the first few months after bariatric surgery. Hypohydration is a common cause of fatigue, poorer mood, anxiety and depression. At Houston Weight Loss Surgery Center, we strongly encourage our patients to sip on water continuously throughout the day especially in the immediate postoperative period. Do not wait until you feel thirsty to drink water especially in this hot and humid weather. If you recovering from gastric sleeve surgery avoid going outside for long periods of time. You may not be able to keep up with water losses and you may end up dehydrated very fast.