Exercise is great for us, builds stronger bones, reduces our BP, excellent for heart health, all round bon oeuf tout circular as the french wouldn't say however, it will not help you lose weight, it may help you maintain your weight once you have lost it, but as far as losing pounds or even ounces you can forget it.
Why? There seems to be a variety of reasons and there are dozens of studies out there on the internet which you can access trying to explain this - it is well known that you have to run between 35-45 miles to lose a pound of fat (depending on which equation for calorie burning you use), studies that show the hunting tribes of Africa use up no more calories in their day long search for meat than sedentary americans in their day long search for cheap processed food, distressing but true.
But the real point of this post, if you are making yourself totally miserable at the gym with pounding on the treadmill, sweating away at the rowing machine, watching the calories burned on the digital display and thinking i've just run off that orange juice i had for breakfast now to run off the cereal then stop, you will do as much good to your body with a lovely walk through the park or in the woods with far less misery attached and none of grim aspects the gym has to offer, and keep being mindful about what you eat and keep being mindful about how often you eat - the longer you can leave it between meals the longer your body has a chance to use up the energy from your last meal. Maybe even try the 2 meals a day option to change up your way of life and no snacks in between.