Once when I had to look better fast - I almost did not eat anything but vitamins and ran, walked, biked a lot for two weeks or so. Lost 6+lbs in 15 days, but I felt very exhausted and pretty unwell...
Losing weight FAST usually does not last long - your body will react after stopping to starve: namely it will stock everything it can, so the body weight will increase higher that it had been before. Yo-Yo effect.
Nowadays I walk to work and back - 20-25 minutes daily + some running once a week on my treadmill. This worked I lost approx 10lbs within a year and I feel Good,
Cheers,
Chill