You might be over simplifying things a bit. Your statement might be true for "healthy bodies" but not everyone is healthy, or even has the same body chemistry.

You might be over simplifying things a bit. Your statement might be true for "healthy bodies" but not everyone is healthy, or even has the same body chemistry. I'm by no means an expert and the subject of obesity doesn't really interest me that much, but the other day I was reading something about obesity in relation to the over prescription on antibiotics, and how especially children who received antibiotics during their childhood might have obesity problems later in life due to how the antibiotics affect the gut bacteria. Again I'm no expert, but the calories in/out story seems just way to simple.