Cardio is not the way to lose weight. Proper diet will net you losses even if you avoid the gym though.
Pair a good diet with low weight/high rep weight lifting, you will cut up while losing lbs. I used to run competitively and can tell you that running even up to 70 miles per week does very little for me in terms of weight loss. Some runners will actually gain weight at a certain point, say they are running 70 miles per week and increase to 85 or 90, they begin to gain weight.