There's this great book 'Why calories don't count' by Dr Giles Yeo. It discusses how the human body processes food and extracts energy from it - and how current calorie labels on food items don't account for this process. Highly recommended.
Thanks for the link. I agree with Seth that consciousness is much like a controlled hallucination - after all, we don't experience reality directly, but through the predictions of our brain. But then the question is, why do you need this hallucination? I suspect that consciousness evolved because it makes an organism more capable than one who doesn't. But what does consciousness offer over just taking in sensory input and making predictions without having qualia (much like a computer does)?