I have tried both diet and exercise and while both are nice, I've had the best luck losing weight by going on the diabetic exchange diet. You figure out how many calories you need per day and then you can eat using the exchange lists to figure out how much you can eat of whatever food.
It has the benefit of NOT being some fad diet, real doctors worked it out and it is well-balanced with the different foods you need for good nutrition.
Good, sustainable weight loss is not a rapid process--losing weight too quickly is not healthy and the faster you lose it often means the faster you can get it back.
You don't eat a lot of meat with this diet but it's there--lots of veggies in it and you'll be amazed at how full you can get if you are choosing the right foods.
Exercise alone doesn't do much, a proper balanced diet is vital to lose weight.
Exercise is great but remember that muscle weighs more than fat so if you are losing inches, but not weight, you may be building muscle mass. BMI is a joke.
Take pictures from the same distance, and angle with something you can use as a size reference so you can visually compare your progress.
Some people due to genetics or other factors may diet and exercise thier hearts out and not see much change--that happens but that diet and exercise will still reap you some substantial health benefits even if you don't lose a lot of weight.