How many calories your body burns along with it's metabollic rate is more dependent on your lifestyle and gene make up. Take this article on how so many of the Biggest Loser contestants gained more weight back after they lost it. "Metabolic suppression is one of several powerful tools that the brain uses to keep the body within a certain weight range, called the set point...When dieters’ weight drops below it, they not only burn fewer calories but also produce more hunger-inducing hormones and find eating more rewarding." Basically, a person who used to weigh 300 and now weighs 200 will burn fewer calories and have a lower metabolism than the average 200 lb person.
Or the Atkins diet for example (which fell out of favor back in the 20th century). Removing all carbs can alter your body's hormones that signal insulin. Something called cellular inflammation is the result and the next time you decide to eat a pretzel, your body reacts badly and puts back that lost weight.
What's the Solution? No one's perfect and we have to think long term. Try cutting out one minimal thing. For me, it was processed fast food. I still find myself on the occasional trip with a fellow coach demanding to stop at Culver's for "butter burgers." I'm ashamed to step inside a joint that rakes in cash selling something called "butter burgers" but that's the small price of having his company.
It's best to just stick to the old saying, "everything in moderation." I try to eat well rounded meals and maybe just a little less than I used to when I was younger. And of course, exercise. Getting plenty of exercise and eating healthy after is the most natural way to keep up your metabolism.