Losing weight is most commonly about lossing fat (reserve calories). Diet is controling caloric intake, but excercise will burn more calories. The most important and lasting factor is the change in mindset and the ability to wait to be healthier.

If you're body is like a drinking glass and water is energy in the form of calories. Reducing your caloric intake is like putting less water in the glass. If you're not active, its like sipping on the water to lose mass. If you work out and exercise then its like taking big gulps of water.

Please do not consider anything short term. This is a long term life changing mindset.

Good luck.