Why Drinking Enough Could Protect Against Obesity

A research team led by Richard Johnson from the University of Colorado investigated the biological mechanisms by which animals prevent dehydration during hibernation. During this phase, in which they often do not drink for months, water is produced through the metabolism of fat and glycogen, stabilizing the animals' fluid balance.

Hormone Plays Central Role

Vasopressin, a hormone that regulates water balance, plays a central role in mammals. It was already known to be significantly involved in the initiation and maintenance of hibernation. "In our study, we summarized the connections between vasopressin and the accumulation of fat reserves before hibernation in various animals and compared it with human obesity," explained co-author Johanna Painer-Gigler from the Research Institute of Wildlife Ecology (FIWI) at the University of Veterinary Medicine Vienna to the APA.

In the fall, the production of vasopressin increases in hibernating animals. This stimulates a carbohydrate-based metabolism, which is associated with thirst, increased water intake, and the storage of glycogen and fat. As winter approaches, the vasopressin level begins to decrease, the animals switch to a fat-based metabolism, and enter hibernation.

Water Production During Hibernation Is Not Enough

During this phase, water is produced in the body through fat metabolism. At the same time, the release of vasopressin is suppressed, and the concentration of dissolved substances (osmolality) in the blood serum decreases, which in turn suppresses the feeling of thirst. "We suspect that the water production from fat cannot keep up with the organism's water needs," said Painer-Gigler.

Additionally, due to shallow breathing during hibernation, an acidification of the blood (respiratory acidosis) develops. Therefore, the animals must wake up, warm up, and switch to carbohydrate metabolism for a short time. In this process, glycogen, a carbohydrate stored in the cells, is broken down, rapidly forming water in the body. This also facilitates breathing and thus corrects the acidification of the blood. Once everything is back in balance, the metabolism switches back to fat metabolism and hibernation continues.

Significant for Understanding Obesity

"Our observation that obesity serves a natural purpose, namely to ensure survival, particularly through water storage in times of scarcity, could also be significant for understanding obesity in humans," emphasized Painer-Gigler. The scientists suspect that in humans, fat storage is triggered by faulty regulation.

Fructose could play a role in this, whether from food or formed in the body. The fruit sugar is likely to influence the signal transmission by the "hunger hormone" leptin, as well as the production of vasopressin, and subsequently promote thirst - "a process that is additionally stimulated by salt intake," according to co-author Szilvia Kalgeropoulu from FIWI.

Connection with the Effect of Weight Loss Injection

Most people with obesity also have an increased vasopressin level in the blood and show signs of dehydration. Therefore, they consider adequate fluid intake - not least due to the ever-increasing temperatures caused by climate change - to be crucial for good health. The effect of GLP-1 receptor agonists like semaglutide as a "weight loss injection" could also be partly due to their known ability to inhibit vasopressin production, the researchers suspect.

(APA/Red)

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