What workouts or diets can help a person lose stomach and thigh/leg fat?

Interval training: The best form of exercise you can do is a combination of cardio and strength training, called interval training. Using cardio and light weights you gain muscle and decrease fat. I use the nike training club app on my phone. There are likely interval classes at your local gym. You can specifically target your abs and legs as well. You'll see results in weeks, it's really a great workout.