Instead of pleasure, Small says overeating is likely triggered by unconscious processes, metabolic signals carrying the body's perception of the energetic value of a food based on prior experience. These signals can cause conditioning within the brain over time. The study adds fuel to a debate dividing obesity research into two camps.
Correct. No opposition to this. Hormones carry signals. Tissues, including the brain, then obey the signals accordingly. But the next part of her statement "carrying the body's perception of yada yada" is completely wrong. It's wrong because it presumes some ability to carry quantity/quality information of some sort. There's no such form of information in the signals hormones carry. The hormones are the signals themselves.
A good analogy of what she said is data packets, where each packet contains some information beyond its own means to be received. Hormones carry no such thing. Instead, the quantity/quality information is directly proportional to the absolute quantity of the hormone molecules, then of the receptor sensitivity, then of modulators. In common parlance, we're talking the level of a hormone, as in blood insulin level and so forth.
For the behavior conditioning part, there's no doubt that hormones are involved. However, for conditioning to occur, external stimuli must be present, hormones alone are insufficient. Conversely, conditioning also occurs without excess fat accumulation. We've been conditioned to eat a bunch of crap, we've also conditioned ourselves to eat genuine food.
"I believe that the dichotomy is not accurate. A lot of these metabolic signals actually (change) the brain's response to the food, and that determines how reinforcing it is. The two systems are integrated." Also, she says, most animals base their eating decision on unconscious drives that do not include pleasure.
Maybe. Food is the cause, metabolic signals is the effect. There's no way to reverse this causality. However, hunger is also the cause, while eating is the effect, and hunger is driven by metabolic signals. A reinforcement either way results from the nature of the stuff we consume as a consequence of hunger. If it's genuine food, satisfaction is ensured and this gets reinforced. If it's crap, disappointement is ensured and this gets reinforced instead. We see this all the time when we first go low-carb after years of eating crap. Finally, I'm satisfied with a reasonable meal, instead of being hungry all the time.
The amplitude of reinforcement, i.e. "how reinforcing it is", is a whole nother topic. Two monkeys in a cage. We cannot say that either monkey's behavior is reinforced more strongly than the other, since both monkey's behavior appear to get reinforced equally with equally significant consequences. The one who gets his dose every time pushes the button only when he's driven to, and the dose satisfies every time. The one who gets his dose only once in a while pushes the button continuously also only when he's driven to, but he's continuously driven to because satisfaction never comes. Going low-carb after years of eating crap, we're finally put into that cage where we get our dose every time, satisfaction finally comes, we can now push the button and rely on a satisfactory dose every time. All the while though we're fighting old habits of reaching for that cake.
Personally, I once ate a big mac and suddenly realized it tasted like saw dust.
-edit- It just occurs to me that satisfaction may be a stronger reinforcement effect compared to disappointement. Maybe.