Here it is again. How much exercise is necessary to lose weight? Some want a firm answer or the question would not appear again and again. It is as if "I want to do what I need to do, but no more". You'll find a variety of answers and a study somewhere to support the information. Whenever I need answers, I go to sources such as American College of Sports Medicine. They recommend the most accepted guidelines that adults engage in physical activity a minimum of 30 minutes 5 days a week for healthy reasons. Weight loss is a different story. Their most recent recommendation based on quite a bit of evidence is 250-300 minutes of moderately vigorous exercise per week for a significant amount of weight loss. If weight loss is a concern, commit to 30. It's a place to start. 11% of Americans reach the 30 minute recommendation, 33% never do any exercise and 55% never get involved in vigours activity. A word of caution: the body needs time to adjust to vigorous exercise! Going from 0-60 minutes is not such a good idea.
Source: IDEA Fitness Journal July-August 2011