There is a huge amount of scientific literature (see summaries by Gary taubes, for example) that show that calorie counting is not the whole picture when it comes to health or obesity. It's also definitely not a golden rule.

Not to say it's not a useful diet method. Just that there are a lot of factors that go into "calories out"-- what calories are being used for energy and what are stored as fat. How fast are you burning calories? Hormones are a big part of that. You can see this very clearly in hyper/hypo thyroid patients.

Also, famine makes you passive, tired and well, less bright. There is a reason why famine prone areas dont produce tech hubs and nobel prize winners.