Exercising in cold water may increase your appetite and slow weight loss, according to a new study. "Changes in your body temperature triggers the need to consume more calories" according to Dr Lesley White. This may explain why swimming doesn't seem to drop the pounds as much as jogging or cycling.

“It’s possible that individuals who exercise in cooler water may have an exaggerated energy intake following exercise, which may be a reason why they don’t lose as much weight,” said White, an assistant professor in the College of Health and Human Performance. “So it may not be the exercise itself that causes the problem because you can match the exercise energy expenditure; rather it’s the increased eating after the exercise is over.” Caloric intake after exercise in cold water was 44 percent higher than exercise in warm water and 41 percent higher than in the resting periods. “The practical implication of this study is that cold water temperature could frustrate weight loss by increasing caloric intake."