Interestingly, all responses so far seem to be from other males... It is a pretty well established fact that men lose fat a lot easier than women. I am a woman, 65 years old, and I have no problem getting weight off when I tighten up on my diet and eat the right things (lean meats, fruits, lots of veggies) and cut out stuff like bread and pasta. I have two bad hips (getting the first one resurfaced next month), so I am also limited in how much and what type of exercise I can do. I definitely have had to cut back quite a bit on physical activities because of the pain in my hips.
If I can do it, a man in his 40s should have no real problem getting rid of some weight, other than mustering up the necessary self discipline. I know it's no fun, especially with a lot of weight to lose, but it is definitely worth it in the long run!
Depression is a different issue. Many people overeat when they are depressed. I agree with hipnhop that it is important to watch out for it, and get treatment for it if necessary.
Best of luck to you, both with the surgery and the weight issues!