A few years ago I decided I had gained a few too many pounds and decided to start exercising more and “dieting”. I lost about 15 pounds and then eventually plateau even though I would exercise a decent amount on a regular basis. I started to do some research and came to realize that losing weight is approximately 80% diet related and 20% exercise related. I decided to start tracking my calorie intake and to my surprise I was consuming way more calories than I thought I was consuming. Stuff that I thought was “healthy” was really not—a quart of Gatorade, granola bars, etc…
I was consuming ~3000-3500 calories a day without realizing it. I slowly started modifying my diet and then I started to lose more weight. No specific designer diet, just less food. I lost 30 pounds over ~2 years and now have a good feel on my calorie intake so I don’t track everything I eat.
I would suggest tracking your food intake for a few months to understand where you’re at, it might surprise you.
There’s a few sites, I used to use the Livestrong site and then switched over to MyFitnessPal after they upgraded the Livestrong site.
Good luck.