Obesity is common in the United States, with more than 1 in 5 people in the United States being obese. [1] The figure below represents that some areas of the U.S., such as the Midwest and the South, have even higher rates of obesity.

United States has one of the highest rates of obesity, but it is a problem in other areas of the world as well. The map below portrays the rates of obesity across the world in 2016.

Yet, what do we know scientifically about obesity and Metabolic Syndrome? Each area in the world has a different diet, so how does the food commonly eaten in the United States contribute to the high prevalence of obesity?

What’s Happening in the Body During Obesity

The hypothalamus, a region in the brain, is responsible for our appetite and eating behaviors. There are AgRP neurons and POMC neurons inside the hypothalamus. The AgRP neuron signals tells us we’re not full, while POMC neuronal signals tells us we’re full. The yellow AgRP neurons will activate the blue MC4R neurons, the “eat” neurons so we keep eating, while the POMC neurons will inhibit the MC4R. In other words, the POMC will make sure the “eat” neuron, the MC4R neurons, will stop telling us to eat.

However, in obesity and metabolic syndrome, this process goes out of balance. The AgRP neurons will continue activating the eat neurons, and the POMC neurons won’t tell us we’re full, so we end up eating more than we should because we don’t feel full.

Impact of a High Fat Diet on our Bodily Processes

Obesity also causes low-grade inflammation throughout the body that can disrupt important processes, including neurons such as AgRP and POMC. Some of this inflammation can arise from a high fat diet, even within a few days after a high fat diet. This diet can cause acute inflammation in the hypothalamus. [5] Chronic consumption of a high fat diet will perpetuate the inability to feel full when you’re supposed to.

A high fat diet is when 30-60% of calories consumed are from unsaturated and saturated fats. [6]

Saturated fats trigger inflammatory pathways, and decrease insulin and leptin sensitivity, something that helps us break down food into nutrients. Meanwhile, unsaturated fats help increase insulin and leptin sensitivity which helps us break down our food into their nutrients. [8] Saturated fats are harmful in large amounts; unsaturated fats are helpful!

A Reflection on Common U.S. Foods

Considering that foods that are high in saturated fats such as fried food, red meat, chips, vegetable oil, and dairy products are in the everyday diet for a lot of Americans, it’s no wonder the obesity rate is so high in the U.S. compared to other countries. Especially considering our large portion sizes that encourage over-eating.

Food is not the enemy, neither is saturated fats in low amounts, but it’s important to have balance in our diets to ensure a healthy life. A hamburger and fries won’t completely harm your body, but it’s beneficial to limit the consumption of these “bad” foods and balance it with healthy foods.

 

References 

[1,2] CDC. (2024, September 12) Adult Obesity Prevalence Maps.  https://www.cdc.gov/obesity/data-and-statistics/adult-obesity-prevalence-maps.html

[3] Ritchie, H., Roser, M. (2017, August) Obesity. Our World in Data. https://ourworldindata.org/obesity

[4,5] Jais, A., Brüning, J. C., (2017). Hypothalamic inflammation in obesity
and metabolic disease. The Journal of Clinical Investigation, Vol. 127(1): 24-32. doi:10.1172/JCI88878.

[6] Willebrords, J, et. al. (2015). Strategies, models and biomarkers in experimental non-alcoholic fatty liver disease research. Progress in Lipids Research, Vol. 59: 106-125. https://doi.org/10.1016/j.plipres.2015.05.002

[7] YMCA. (2022, June 1). Four Myths About Eating Fats. https://lafayettefamilyymca.org/myths-about-eating-fats-2/

[8] Jais, A., Brüning, J. C., (2017). Hypothalamic inflammation in obesity
and metabolic disease. The Journal of Clinical Investigation, Vol. 127(1): 24-32. doi:10.1172/JCI88878.