What is the most effective and safest recommended weightloss program?

Lifestyle. Bottom line to loose weight is you need to burn more calories than you take in . Eat smarter/smaller portions or burn more calories by exersizing. Both at the same time is ideal. Make small consistent changes and the long term weight loss and health benefits will follow. If a program is needed for motivation and education then weight watchers has a good, sensible program.
Diet and Exercise. The goal is to burn more calories than you consume. Watch your diet; eliminate junk food and don't over-eat. Consider liquids as well; soda, alcohol, etc. Contains lots of calories. Exercise multiple times a week. If you find an activity you really enjoy you'll be more likely to engage in that activity. Avoid fad diets that could prevent you from getting adequate nutrition. Make healthy choices!