Another blow to the mindless thermodynamic theory, and hope for a breakthrough:

Slimming bacteria work their magic in either of two ways, studies of gut microbiota show. They seem to raise metabolism, allowing people to burn off a 630-calorie chocolate chip muffin more easily.

They also extract fewer calories from the muffin in the first place. In contrast, fattening bacteria wrest every last calorie from food.

Transferring slimming bacteria into obese people might be one way to give them the benefits of weight-loss surgery without an operation. It might also be possible to devise a menu that encourages the proliferation of slimming bacteria and reduces the population of fattening bacteria.

I’ve always been thin, regardless of what I ate (though as I got older, I did put on a few pounds, which came back off when I went paleo), and have never felt particularly virtuous about it. I don’t have much patience for thin people who lecture fat ones about their caloric intake. People do have different metabolisms, and what you eat can affect it, but the “diet and exercise” nazis don’t want to believe it.