William Broad rightly points out that yoga slows metabolism, and as such would not seem a good way to lose weight.
However, yoga actually does help people lose weight three ways, maybe four:
- A few well-selected poses done 20-30 minutes before eating will stretch the stretch-receptors in the lining of the stomach, generating inhibitory signals that are sent to the appetitive centers of the brain. [before-after Picture of Hal]
- Nervous overeaters are calmed by yoga.
- Yoga improves interoception and engagement with your muscles and organs. It makes you more aware of your body, and better able to recognize when you are satisfied. The more you feel the stomach and the abdominal musculature, the less you are inclined to stretch them from the inside.
- This still must be considered somewhat speculative: The recently discovered neurotransmitter orexin (as in its opposite ‘anorexia’) alerts mammals to satisfy their appetites. Yoga, in general, being a parasympathetic activity, decreases orexia.