How Starving Rats Explain Human Obesity Posted on 10 Jun 11:21
As a proud alumnus of Tufts University, I'm always excited to read their online publications. There are always interesting articles about faculty research and its applicability to modern human life. A new piece* looks at the work of Dr. Emmanuel Pothos who investigates the neuroscience of obesity in animals. The crux of the article is that Dr. Porthos' work demonstrates that the brains of obese animals have messed up reward circuitry in the brain. Curiously, the obese animals exhibit the same pattern of dysregulated dopamine (the primary reward hormone) as animals undergoing starvation. Initial research from this lab suggests that this problem with reward circuitry can become permanent without intervention (and the intervention they recommend is exercise, which seems to correct our own endogenous reward pathways).
I don't know the specifics of this research - and I haven't read any of Dr. Porthos' papers - but it's worth noting some of the questions raised by this work and how they relate to the way that we think about obesity. This isn't the first time that researchers have noted similarities between the two states, which would seem on the surface to be opposites. In fact, the alternative hypothesis of obesity suggests that these states are two sides of the same coin. Many patients with obesity, the alternative hypothesis suggests, have elevated levels of a hormone called insulin, which screws up its ability to act normally in the body. Insulin is the key that allows cells in the body to take up nutrients that are required for their normal activity. When insulin levels are chronically high, most of your cells become resistant to its action; at this point, your body can't use food for fuel and instead locks it up inside of fat tissue. So while your fat cells are getting bigger, the rest of your body is starving, at least according to the alternative hypothesis. The relative cellular starvation then increases your appetite, which only makes you put on more weight.
To see additional connections between starvation and obesity that change the brain in similar ways is curious. While it isn't evidence of an alternative hypothesis at play, it does raise a number of questions.
*I don't want to be too critical here, but I'd be remiss if I didn't note that I disagree with the very premise of the article - that the only way to lose weight is to eat less. The article ends with a platitude about eating less and exercising more - the exact conclusion you might reach if you ignored the last decade or so of obesity research. Most researchers will agree that the hormonal influences of food, particularly that of insulin, play a crucial role in weight changes and energy partitioning.