The best diet for a sedentary person is to increase the fibre and decrease the fats and simple carbs.Make your metabolism rate higher. Since you can walk, do it as much as you can as it will burn the calories and fats.I made my metabolism rate higher by going low carb low fat high fibre high protein and doing brisk walking 5 times a week. And I lost 31 lbs. and decrease my cholesterol, triglycerides and blood pressure.If you exercise lesser, you simply will lose slower. But it is good to lose slowly. Take care.My experience is in my blog
http://lowcarblowfathighfibrehighprotein.blogspot.com