Well, you probably used a calorie budget based on a few simple statistics like your sex, height, and weight. With individual differences is metabolic rates, it'

Well, you probably used a calorie budget based on a few simple statistics like your sex, height, and weight. With individual differences is metabolic rates, it's very possible that your "slight calorie deficit" was actually breaking even for your individual calorie usage. Just as likely is that the nutrition info on labels is imprecise or even systematically inaccurate. For example, I believe there are penalties if your box says it contains 1 pound and it actually contains less, but there's no penalty for putting in more, since only in the former case is the consumer getting shortchanged, and this asymmetry probably creates an incentive for systematic underestimation of net weights, and therefore underestimation of calories per food package. Probably some combination of these factors explains why you need to "ear FAR less than you should need to" based on how the math works out. I still think counting calories can be useful, but only in relative terms, not absolute.