Stephen Kintz
Jan 17, 2012

Fighting obesity: Fat receptors bring hope of slimmer waists

Obesity is not an American problem. It is a worldwide problem. The World Health Organization (WHO) estimates that worldwide obesity rates have doubled since 1980 to around 1.5 billion people in 2008 [WHO]. Our waistlines are expanding, and our bellies are encroaching further and further beyond our beltline. With the immense and unchecked availability of fatty foods in developed nations, it can seem hopeless. I am dreaming about a chocolate custard donut, right now, as I write about obesity. People love fat.

Luckily for the obese and fat-addicted of the world, researchers are beginning to unravel how our bodies taste and respond to fats.

New research from Washington University in St. Louis and published in the Journal of Lipid Research has revealed receptors in the mouth capable of tasting fat. The new research, led by M. Yanina Pepino, demonstrated that participants were capable of detecting fat from a blind taste test, without the use of other senses. The research also investigated how much fat is required to activate the receptors on the tongue. What the research discovered was not surprising. Heavier participants generally required a higher threshold of fat to make detection possible [Washington University Press Release].

This research conforms to previous research that demonstrated fats detected on the tongue activate the endocannabinoid system that is responsible for fat intake and the rewarding feeling associated with fat intake [Cosmos Magazine], and animal studies that indicate that as mice got heavier, they produce less of the protein CD36, which has been implicated in our ability to taste fat. This new research, along with previous research, suggests that some individuals might require more fat to get the same satisfying feelings as other individuals, and that diet, as well as the genetic components tied to protein CD36, affects how readily a person can taste fat.

So will this research allow us to fight back against encroaching waistlines? Fortunately, researchers do appear hopeful that continued research will yield information and possible medicines to fight the current obesity epidemic. The most readily available solution is using the research to change our understandings of a healthy diet. Basically, the research suggests that a high fat diet will lead to the production of less CD36 protein which will cause the individual to need more fat to satisfy their cravings. This is a vicious cycle and, unfortunately, many of the popular fad diets are high in fats. The Atkins and Paleolithic diets both recommend fat levels similar to or higher than typical Western diets. This research (along with the common sense to avoid fad diets) might suggest avoiding these diets.

As for medicines, researchers are pursuing several lines of research that might produce medicines to fight obesity. It seems reasonable to assume that if researchers find a method for controlling the CD36 protein in obese individuals, obese individuals would be satiated with a lower threshold of fat. This would probably work much like insulin.

However, the CD36 protein is a widespread protein that is found in different levels in different tissue. While low CD36 protein levels leads to a higher fat threshold for taste detection, low CD36 proteins in the intestines leads to lower and slower uptake of fat into the body. The current research by M. Yanina Pepino does not investigate this almost paradoxical finding, but it appears clear that controlling our ability to detect and uptake fat will not be as easy as controlling insulin levels. It might require medicines that target specific regions of the body.

Most researchers are targeting the intestines because Rimonabant, an obesity drug recently pulled from the market for serious and nasty side effects, has already demonstrated an ability to target the endocannabinoid system and block fat absorption. Currently, most researchers are looking for compounds that would block the endocannabinoid receptors used to uptake fat within the intestine without affecting the same receptors located in other parts of the body, like the brain. It is unclear if this is possible, but many researchers are hopeful. This would allow an individual to consume a large amount of fat with little weight gain.

This drug would be a donut lover’s dream. However, it should be noted that just because an individual is not gaining weight does not make them healthy. Only time will tell whether giving people unbridled access to all the fatty foods they desire is a heavenly dream or, more likely, a recipe for a host of other physical problems not associated with weight gain.

Of course, with the understanding of our ability to taste fat, many might hope for a better fake fat. Fake fats are compounds that trick the body into believing it is eating fats without the side effects of weight gain. The current crop of fake fats have the problem of activating the endocannabinoid system, which means the body is expecting calories that will never come. When the calories do not come, the body goes into starvation mode. This leads many to overeat. A better fake fat would need to overcome this predicament.  

So while scientists are looking for a magic pill or compound that will allow us to glutton ourselves into oblivion, none are currently available. In fact, most of the research with fat receptors is currently done on animals. So we are a long way from having a magic pill that keeps us skinny, and I am a long way from having the ability to sit down with four dozen donuts without feeling guilty and sluggish the next morning.