There’s no denying that Americans’ collective waistband is growing tighter. According to the CDC, around 36% of adults and 17% of children are now considered obese – the highest it’s ever been. And not only did this epidemic cost US taxpayers a paltry $147 billion in 2008, but it also contributes to a plethora of other diseases including heart disease, cancer, and diabetes (1). Despite what many daytime TV ads try to tell us, dietitians and doctors say that the best way to combat obesity is through healthy diet and exercise.
Which bring up the question: what’s going on in our brains that make it so hard to eat healthy?
The answer that neuroscientists point to is our endocannabinoid system. While there are several other functions of the endocannabinoid system the main role it plays in our body is regulating our appetite. Namely, when endocannabinoid receptors like CB1 are activated by neurotransmitters such as AEA to produce feelings of hunger. However this obviously isn’t the whole story. Here are some ways that the endocannabinoid system influence our eating habits on a larger scale:
Endocannabinoids increase our sensitivity to sweetness and high-calorie foods
It’s no secret that we as humans love foods that are sweet and high in calories, and there is science behind the reason why. Generally, foods that are sweet are also high in calories and our endocannabinoid system rewards us when we continually eat sweet food. CB1 receptors found on the tongue were also found to react more strongly to high-fat foods. One experiment even found that ingestion of high-fat foods caused dopamine outflow in the ventral striatum, an important mechanism for reward (2).
Looking at food increases endocannabinoid levels
For most of us, even the sight of food elicits an emotional response. This is no accident. Endocannabinoid receptors are even localized on the retina and are important in mediating palatable memory by activating the endocannabinoid system found in the brain. Thus, our food preferences are strengthen by these implicit food memories (3).
Food and substance addiction work the same way
Food and illegal substances (meth, cocaine, marijuana etc.) all use a similar pathway to promote addiction. More specifically, food and substance addiction both activate the brain reward dopaminergic and opioid systems. When it comes to food addiction, some studies have found that there is compromised dopaminergic signaling and downregulated dopamine receptors in obese patients. Another study found that subjects that were considered obese had increased dopamine release in respond to food cues (4).
Sources:
- https://www.cdc.gov/obesity/data/adult.html
- https://www.ncbi.nlm.nih.gov/pubmed/22561130
- Bouchard, J.-F., Casanova, C., Cécyre, B., & Redmond, W. J. (2016). Expression and Function of the Endocannabinoid System in the Retina and the Visual Brain. Neural Plasticity, 2016, 9247057. http://doi.org/10.1155/2016/9247057 ▲
- . DʼAddario C, Micioni Di Bonaventura MV, Pucci M, Romano A, Gaetani S, Ciccocioppo R, et al. (2014): Endocannabinoid signaling and food addiction. Neuroscience Biobehavior Reviews 47:203–224.
