There are studies where insulin administered to a mouse's brain is effective against obesity. For a while, "insulin is not obesogenic types" were very fond of this as evidence for their case. It's hard to say how bad an argument I think that is nicely. Systemic insulin has the whole body fighting over whatever glucose there is in the blood. Locally elevated insulin--you get those localized fat pads people can get when they inject insulin in the same spot for years on end. In the brain--you get a small area taking up a little more glucose. Massive insulin will starve the whole body of glucose. Local elevation of glucose just has local cells taking in more nutrients. It's the difference between starving the brain of nutrients, and increasing nutrition locally. So-called obesity researchers who write popular blogs sometimes skip the distinction. This is stupid. See? Hard to say it nicely.