Best exercise routine to lose fat and gain muscle?

Aerobic + resistance. National guidelines recommend 150 min/wk of moderate or 75 min/wk of vigorous activity and resistance exercise twice/wk. If you want to lose weight you'll probably need to exercise more and eat less. Moderate means you can carry on a conversation while exercising and vigorous means you can't. For more info, check out http://www.Cdc.Gov/physicalactivity/everyone/guidelines/index.Html.