Jogging might not be the best form of work out, particularly if you wish to shed extra body weight.

Greg Brookes, a London-based personal trainer, said, "Lots of people start running to lose weight and it doesn't always work - and this is why."

Brookes said, "Fat is one of our body's favourite sources of energy. The more you run, the more your body prepares itself for your next run. You will actually start to hold on to more fat."

Brookes, whose client list includes celebs, highflyers and homemakers, suggested why you won't get thinner is that the body is an amazing machine and will adapt to anything.

"The more time you spend running, the better you become at running and the more efficient you get, the less energy you use and the fewer calories you burn," says Brookes.

According to him, jogging exercise is also terrible for joints.

"When you run, two-and-a-half times your bodyweight is transmitted through your joints."

"If that force is repeated over and over, eventually your weakest joint will give out. Usually the ankles or the knees are the first to go," he added.

In contradiction of popular faith that any work out will accelerate your metabolism, running can, said Brookes, do the opposite. (With Inputs from Agencies)