Everybody in the pool...unless you’re trying to lose weight

After a tough workout there’s nothing better than sliding into a chilly pool to cool off. That cool-down might have a down side, however--increasing your appetite.

A study found that water immersion following a bout of exercise may make exercisers likely to eat more compared with those who didn’t get into the water. Australian researchers tested 10 physically active men who went through three experiments. In each they ran on the treadmill for 40 minutes, but in one they were immersed chest-high in cold water (59 degrees Fahrenheit), in another in tepid water (91 degrees Fahrenheit), and in the third they sat and rested, all for 20 minutes. Following the rest period was a buffet breakfast where participants were allowed to eat as much as they wanted.

Researchers also collected the study subjects’ blood samples to test for blood glucose, lactate, and hormones such as leptin and ghrelin. Leptin tends to decrease appetite, while ghrelin increases it.

Test subjects ate more after both water immersions than they did after sitting in a chair. Average calorie intake per person after the cold water immersion was about 489, and about 517 after the tepid water immersion. After resting in a chair, average calorie intake was about 409. Researchers found lower levels of leptin and higher levels of ghrelin after both water immersion experiments. Following water immersion more carbs and protein were eaten as well.

In the study, the authors wrote, “Further research, ideally including larger sample sizes, is needed to determine if this is an important consideration for athletes trying to manage their weight, particularly those competing in sports that involve the adherence to a strict weight class or where excess body mass may inhibit performance. On the other hand, the greater energy intake following water immersion may be beneficial for the purpose of replenishing depleted fuel stores following an intense bout of exercise.”

The study was published online in the journal Medicine & Science in Sports & Exercise.

--Jeannine Stein / Los Angeles Times