The best weight loss motivation is to be healthy and happy in your own body. Celebrities find themselves under so much scrutiny and media attention that they sometimes go to extremes lengths to lose weight.
The worst thing about celebrities and weight loss is that the pressure to be so thin and beautiful causes celebrities to feel the need to downplay the amount of effort they put into losing weight. Britney Spears said that she just does some aerobics and weight training for three days a week to get back to her pre-pregnancy body. If it was that easy, we would all look like Britney Spears!
According to the Centre for Disease Control and Prevention, they recommend you do moderate exercise for 30 minutes a day, 5 days a week.
http://papario.com/2009/06/08/weight-control-tip-of-the-day/