I do not think it is possible. You can loose weight by not consuming anything (not receiving proper nutrition) and it can be damaging to the body. Also without the proper nutrients is would be hard to maintain fitness because you would lack energy.
Fitness trial is artificial for jogging or running having installed obstacle in between. A person should cover this length in due duration to stay fit.
This fitness trails is also known as trim trail. It helps to stay fit because all the obstacle and equipment installed in the path helps to complete all the outdoor exercise for a person to stay fit.
People of all ages are advised to do some physical outdoor exercises to stay fit. Specially women are advised to complete training on fitness trial to stay fit in their old ages. Sometimes kids are found doing the same.