you can get information fromhttp://www.maintain-health.blogspot.com
1) Eat less2) Exercise moreIdeally a balance, but you can do it with all one or the other. Success for me was cutting out fast food and sugars (candies and soda) and exercising at least 30 minutes at least 3 times a week. Dropped 12 pounds in two months.
DETERMINATION !!!!
Record and evaluate the nutritional value of EVERYTHING you eat...including tasting while cooking, and picking here and there...BE AWARE....we hated the recording aspect of improving our diet but it really makes a difference. We tried calorieking.com diet and exercise manager...there is a one week free trial...check it out...it helped us loose 40 lbs between us in two months! Play around with it and it will calculate cals, carbs, protein, and fiber for you...it will do a million other things if you really investigate.
If you have the $$$ go for professional slimming centre.
Firstly, of course DIET and EXERCISE. Everyone is going to tell you that. Also, stay motivated and focused which can be hard. Some people keep food journals to keep on top of how much they are eating and what they are eating. I would say to start with 3 days for 30 minutes a day then increase slowly to 4, 5 etc...what you can handle. DON T over do it. 20 lbs is sort of a lot, so be prepared to be in it for the long haul even after your goal weight is achieved. This is a commitment.