Could this work and how long will it take??

You probably would but you might also gain it back quickly as soon as you stopped. One hour a day of exercise is enough. Mix up the running, biking and walking and take off one day a week from exercise so your body can recover. Add in a salad and only eat about 4-6 oz of meat a day. I'd also do some weight lifting, like maybe some pushups and sit-ups so you keep your muscle tone.