Sorry to say but the only way you can lose 50 pounds of fat is by eating the right stuff in the right amounts at the right times. Only doing cardio exercise and eating unhealthy will keep your heart and lungs healthier which actually will make losing fat harder. Sounds nuts but the lower the heart rate the harder it will be and a healthy heart beats less. Try to eat better, I know its hard its my weakness too. Good luck and strong mind.