Walking will help your heart and is a good way to improve base fitness, but generally speaking not a way to lose weight. Fundamentally, walking burns very few calories. To lose 50 pounds walking, you need to walk hours per day which isn't very practical.

That said, it can still work because ritualizing fitness also brings more awareness to other aspects of your life. When you are regularly working out (walking or otherwise), it can make you conscious of mealtime choices. You also are fundamentally not eating when you are out walking.

If you want to lose weight, you either need much more intense exercise or to figure out how to stop eating. Walking or other activity is still important, but it's not a "Weight loss" solution.