When fat is metabolised to release energy, the carbon and hydrogen atoms combine with oxygen to form CO2 and water. Fat is a mixture of hydrocarbons. Each gram of fat broken down in this way releases just over a gram of water. Surprisingly though, camels can’t make use of this H2O. The oxygen needed to break down the fat means they need to breathe more and overall they actually lose water via their lungs. A camel’s hump enables it to store food, but water is located in all the body’s tissues. Camels can withstand incredibly high levels of dehydration; they can lose 25 per cent of their body weight via sweating – half of that would be enough to cause heart failure in most animals.