Right, and perhaps one of the biggest things to understand is that, while thermodynamics does apply to human exercise and consumption and is really easy to unde

Right, and perhaps one of the biggest things to understand is that, while thermodynamics does apply to human exercise and consumption and is really easy to understand and reason about, the conclusions you get from that tend to be overly simplistic. The problem is a fallacy along the lines of "all humans are perfectly uniform, rational decision-makers." Instead different foods release different chemicals in your brain over different timelines, causing your cravings for food to be different. Just to take the simplest case, there is something like a 20 minute delay between food hitting your stomach and any sort of satiety signal hitting your brain. So if you have an abundance of easy-to-eat food, then you may end up consuming more calories than someone who doesn't. (You could call this the "second bowl of cereal effect": when you've eaten a bowl of cereal and still feel hungry afterwards, it's because you ate too fast because you didn't want the cereal to get soggy.) Easy weight loss plan: cook your own meals, tasting along the way; by the time you're sitting down with the food you won't be quite so hungry. And none of that picture has to do with calorie-counting. Calorie-counting is important if you can stick to it, but most people keeping informal calorie-counts will be victim to their cravings, and those cravings are dictated by parameters of the food other than the food's caloric content.