Obesity Causes Confusion Between the Brake and Gas Pedals

The yoyo diet explained in one graphic.

The yoyo diet explained in one graphic.

It’s a fact pretty well known by just about anybody who’s ever gone on a diet. Once you get the weight off, it’s difficult to keep the weight off. Depending on who you talk to, as much as 80 percent of temporarily successful dieters eventually gain the weight back a couple of years later, embarking on the so-called “yo-yo” dieting pattern. Just look at Oprah and Kirstie Alley for prime examples.

Of course, there are plenty of people who dispute this fact, and there are a lot of different estimates out there. And there’s just as many theories as to why this phenomenon is even a thing. Here’s one, however, I recently came across that might have some substance to it.

When you get fat, chemical and physical changes occur in your brain to reset your “normal” weight, causing your body to always push toward that upper fatty threshold.

The evidence comes from a recent study out of Indiana University. The researchers say they have found evidence of neural changes in synaptic chemistry that cause obese people to continually feel the need to overeat and maintain their weight.

Here’s how the finding works.

The pangs you feel in your gut indicating that your hungry don’t originate there – it’s your brain that tells you that you’re hungry, not your stomach. Hunger is controlled – at least in part – by a region of your brain called the hypothalamus, which also regulates other vital systems including pain, mood, stress response, and memory. One way in which food consumption is regulated in this region is through cannabinoid receptors.

Cannabinoid receptors normally sit on nerve terminals and work to inhibit neural activity, and thereby regulate hunger and consumption. In a typical brain, when these receptors are activated, it excites the attached synapse and neuron.

But when mice in the study became obese, these receptors became saturated, requiring more and more inputs to activate them. Not only did this cause the neurons to pump out an excessive number of cannabinoids for the receptors to respond to, it also caused their activation to switch from an excitatory role to an inhibitive one. And usually, when the brain’s chemistry gets so out of whack that what used to excite neurons now inhibits them, bad things follow. Plus, because the neurons start pumping out more activation molecules, they also begin churning out more molecules that signal hunger.

As one of the authors Ken Mackie said, “This study identifies a mechanism for the body’s ongoing tendency to return to a heavier weight.”

The findings produce a potential target for therapeutic drugs. Perhaps desaturating these cannabinoid receptors would allow the body to return the production of hunger signals to normal levels.

Of course, maybe playing around with these neurons and receptors will have a completely different effect. Unfortunately, the brain just isn’t that simple.

“These systems are a balance of a very fine webs of regulatory networks,” said Mackie.

The paper, “Obesity-driven synaptic remodeling affects endocannabinoid control of orexinergic neurons,” was co-authored by Kenneth Mackie, professor in the department of psychological and brain sciences at Indiana University, along with a shitload of other researches, as science usually is. They include lead author Luigia Cristino, Consiglio Nazionale delle Ricerche, Pozzuoli, Italy; Giuseppe Busetto, University of Verona, and National Institute of Neuroscience in Verona, Italy; Roberta Imperatore, Consiglio Nazionale delle Ricerche; Ida Ferrandino, University Federeico II, Naples, Italy; Letizia Palamba, Consiglio Nazionale delle Ricerche, and University of Urbino “Carlo Bo,” Urbino, Italy; Cristoforo Silvestri, Consiglio Nazionale delle Ricerche; Stefania Petrosino, Consiglio Nazionale delle Ricerche; Pierangelo Orlando, Consiglio Nazionale delle Ricerche, Naples, Italy; Marina Bentivoglio, University of Verona; and Vincenzo Di Marzo, Consiglio Nazionale delle Ricerche, Pozzuoli, Italy.


About bigkingken

A science writer dedicated to proving that the Big Ten - or the Committee on Institutional Cooperation, if you will - is more than athletics.
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