Will doing spin classes twice a week help me lose weight?

Maybe: Aerobic exercise is exercising for an extended period of time (20 min or more, nonstop) at a moderate level (3-5 on a 0-10 scale). If you do that and lower the calories you take it, then yes, you burn fat! remember to stay hydrated. Hydrate+aerobic=good in general it is better to get 5 or more days a week of exercise lasting at least 22 min. You can do 2 spin classes & 3 days of other stuff!