While aerobic exercises usually burn fat and help with losing weight, this effect is limited in swimming, even though being in cold water burns more food energy to maintain body temperature.
The reason that swimming does not significantly reduce weight is still poorly understood, but seems to be related to the better heat conduction of water. A number of reasons are suspected.
* First, water cools the body much faster than air, and most researchers believe that subsequently the body aims to maintain a layer of fat under the skin for insulation.
* Secondly, it is believed that appetite decreases as your body temperature increases, as for example during exercise. However, during swimming the body is cooled down almost instantly as the surrounding water is usually cooler than the body temperature, and some researchers believe that this may actually increase the appetite. This assumption is not yet proven by research.
* Finally, some researchers also believe that the metabolism of the body increases at higher body temperature, burning more food energy. Again, during swimming the body is cooled down by the surrounding water, reducing the metabolism, and subsequently the amount of food energy burnt. This assumption is also not yet proven by research.