I don't know why people make something like this so complicated. Do not eat more calories than you burn off...and you won't become obese.
The hidden problem with your advice is hunger. Some low-calorie diets produce more hunger than others. The Adkins diet produces less hunger (for me) for the same calorie intake than the so-called low fat diet that my doctor previously had me on. I have been on Adkins (against the advice of my doctor) since January of this year. During that period I have steadily lost weight (over 20 pounds, so far), and my total cholesterol has dropped from 265 to 175. Further, I have more energy, and, in general, look and feel more healthy.
I do not consider my doctor a quack, just a lousy nutritionist. On her advice -- a low-fat diet -- I gained considerable weight, and my cholesterol zoomed to the point that she recommended I go on Lipotor if I could not bring it under control with my diet. That was a Catch-22, for certain. Thank God for Dr. Adkins who had the balls to stand up to the quacks in the medical establishment -- the ones who fed my doctor bad dietary information.
I don't even have to look at your profile to KNOW without a doubt that you are most likely under 25 years old. The do-not-eat-more-calories-than-you-can-burn idea is a lot more complicated that you realize. It's the "can burn" part that has such variables. And like this article alludes to, its the burning of those calories that under some conditions burn easily and fast and in other conditions just don't seem to be burning at all. When I was your age my metabolism was so fast that no matter how many calories I ate, I burned them off immediately. I weighed 102 pounds. I was moderately active, but did not exercise just for exercise sake. In those days (the 60's) girls were not encouraged to do sports and we didn't even know what Nike shoes were. By the time I was 35 years old I had to limit what I ate plus do high impact aerobics 4-5 times a week in order to stay under 110 pounds. By age 45 that became increasingly more and more difficult. Now at 55 years old, even though I play tennis 4 or more times a week, walk a mile or more every-other day and limit what I eat more than I ever needed to before.... I still seem to gain a little weight each year! At this point the old do-not-eat-more-calories-than-you-can-burn idea becomes almost a laughing matter. Bringing intake down to "what I can burn" would virtually be starvation. There are so many other variables involved at this point.
I know you mean well with your advice, but it is just not that simple a matter and to smuggly say so causes older generations so much confusion in trying to handle diet problems. It reminds me of the time after the birth of my first child when I had trouble the first day with breast feeding and the cocky young doctor left me in tears thinking it was all my fault and I was a total failure as a mother. He had told me that I would know instinctively how to do it, after all, all mothers do. But I didn't, and I hated myself!! It took a very kind, very mature senior nurse (actually I don't think she was an RN... but one of the fetch and carry, change the sheets workers), she came by and found me crying, she had feed a few babies herself and knew the routine and a few tips from her and I was off-and-running at it. It all seemed so logical to the highly trained doctor, but you see, he had not been there-done-that.