Image of brain of an obese man. Shows overlay of a normal brain and a smaller obesogenic brain.

Western Diet Makes You Stupid

My hubby found this article, “Western food makes you stupid.” Wow, what a show stopping title! I had to find out what led the author to make such an assertion. This took me on a trip down science lane. Take the trip with me. I learned that the title, Western food makes you stupid,” is overstated. A title which reflects the facts would read, “Eating a Western Diet will reduce cognitive and motor skills and cause dementia in some of us if we make bad food choices for a lifetime.”

Eating a Western diet impacts your brain immediately in subtle ways with an increasing negative impact the longer you overindulge in foods loaded with fat and added sugar. For definitions, follow the link. https://carbohydrateconfessions.com/terms-youll-want-to-know/

This is the first in a series of related posts. Links to be added as posts are written.

Big Body Tiny Brain

When researching this post, an image of the brain of an obese man caught my attention. The image tops this post. Note that the obese brain, shown in gold, is smaller than the overlaid healthy brain (white) because brain cells have been lost (the brain has atrophied). The Getty Image was taken from from a magazine article by M. Schroeder U. S. News 5/12/17. This image dovetails nicely with the Western food makes you stupid article.

Ask yourself this question. Do you want a tiny, stupid brain? If so, keep on scarfing down the Western Diet. If not, read on.

The Bottom Line

A Western Diet is what many of us eat every day. Our diet has inadequate fruits, vegetables, whole grains, legumes, fish, and low-fat dairy products and excessive amounts of refined and processed foods, alcohol, salt, red meats, sugary beverages, snacks, eggs, and butter. The Western Diet is low in potassium, high in sodium, fats, and simple carbohydrates. Remember the Ralph Nader book, Unsafe at Any Speed, which changed our idea of car safety? I argue that eating a Western Diet is unsafe at any speed or in any amount. The Western Diet does make you stupid.

The Western dietary pattern is deemed unhealthy for humans based on a variety of epidemiological findings …. (Davidson, Jones, Roy, & Stevenson, 2019)

Earth Shaking Studies

An article in The Week Magazine 3/13/20 suggested that eating a Western Diet makes you stupid provided a tantalizing summary of an experiment done by a group of Australian researchers (Attuquayefio, Stevenson, Oaten, & Francis, 2017). The article, published three years ago, followed up on a series of animal research studies on rodents both obese and lean by applying the findings to humans. The 2017 study findings have been expanded and updated (Stevenson, 2020).

When compared to students who ate a healthy breakfast, young, lean adults who ate breakfasts which were high in saturated fats and added sugar for only four days were slower to learn a list of words. When they stopped eating the Western Diet, the verbal learning problem disappeared.

What Happens If We Continue Eating a Western Diet

The animal and human research results agree. Eating a Western Diet for a brief time isn’t harmful. It’s okay to binge on chocolate cake. Eating a Western Diet begins to make you stupid in small incremental steps beginning with parts of the brain which are more vulnerable. Over time, the cognitive disabilities cascade and widen.

Think of a leaky metal pail with a small pole at the bottom. At first, only a small amount of water is lost. With time, the hold gets bigger and bigger until the pail cannot hold water. At this point, the brain damage caused by eating a Western Diet can’t be reversed. It’s too late. We’re told that we have a progressive dementia such as Alzheimer’s disease.

The Vicious Cycle Begins

Sanderson and colleagues study a part of the brain known as the hippocampus. They believe that eating a Western Diet causes a vicious cycle starting in the hippocampus which makes it more difficult to stop eating the very diet which is making us sick. Below is my adaptation of the Davidson et al. (2019) Vicious Cycle Model.

Davidson et al. Model of the Vicious Cycle of Obesity and Cognitive Decline

We Devour Ourselves

  • We eat the Western Diet with too much fat and sugar
  • The hippocampus begins to change
  • We can’t suppress thoughts and memories of fat and sugar loaded foods.
  • We need more and more of these harmful foods. And the cycle continues until we are like the mythical ouroboros. We are devouring ourselves.

In the United States, we are eating ourselves to death. Dr. B. Wang

“Digesting the Findings”

To get a handle on the implications of the Vicious Cycle Model, the first thing I had to do was toss my outdated notions of how the brain and digestive system do business.

Take the stomach as an example of the digestive system. I thought that the upper parts of our brains involved themselves with important stuff such as decision making and didn’t play much of a role in the mechanical workings of the stomach. When brain regions did communicate with the stomach, they did so indirectly through lower brain structures, particularly the nuclei of the hypothalamus.

Learn More About the Hypothalamus and the Reward System

We review the hypothalamus, the reward system, and carbohydrate addiction in our book. https://carbohydrateconfessions.com/

Watch the first part of this video from the Khan Academy to see the basic anatomy of the reward system. Watch the discussion of drug addiction and the reward system if you wish.

Watch a discussion on food addiction by Dr. Barnard.

Higher Brain Structures Are Involved

I was wrong to write off higher brain structures. The hippocampus gets direct chemical signals from the stomach. Read Kanoski et al. (2007) to see how the research on Western Diet and the hippocampus is done.

from http://www.kanoskilab.com/asset/img/pubs/53.jpg

Enter the Hippocampus and the Midbrain

In a figure from the Kanoski laboratory, notice that the appetite stimulating peptide ghrelin was secreted by the mouse’s stomach and communicates directly with neurons in the hippocampus. (Follow the blue dots). The hippocampus is a seahorse shaped structure in the midbrain. The location of the hippocampus in the human brain is shown in the next image.

Cells in the hippocampus are turned on by the peptide and can then direct the animal to take action or withhold action. (See gray arrows in D to the left point to activated neurons in the hippocampus.)

Other Players in the Appetite Control Line Up

There are other important players in the appetite control line up– the temporal and frontal lobes of the brain. The important brain areas involved in the reward system are shown in the image. The temporal lobe isn’t shown, but it lies over the hippocampus (Hip). The important pathways between the hypothalamus (NAc or nucleus acumbens) and the prefrontal (PFC) and orbitofrontal cortex (OFC) are shown in red. The CG in the figure is the cingulate gyrus, a huge bundle of nerve tracts which connects the two sides or hemispheres of the brain

Illustration of connections between frontal cortices and midbrain.

What’s Interoception?

Interoception is the sense of the internal state of the body. Interoception can be both conscious and non-conscious. Using the stomach as an example, you feel uncomfortable and “stuffed” after a heavy meal. That’s conscious interceptive information from the stomach. Your stomach secretes ghrelin. You aren’t conscious of that release, but your hippocampus is. Your temporal lobes play an important role in interpreting our bodies interoceptive messages. https://carbohydrateconfessions.com/terms-youll-want-to-know/

Interoception is part of the delicate balancing act which the systems controlling eating try to perform each day. Without interception, the control of eating gets out of whack.

Picture of nerves in human body connecting organs with the brain for the control of interoception.

Organs that provide interoceptive information to the brain, often without our awareness

The Tripartite Model of Appetite Control

Chen and colleagues developed a three-part model which goes a long way toward explaining how we become addicted to sugar and junk food. Chen’s model fits research findings as we now understand them. There could be a better model tomorrow (Chen et al., 2018).

We’ll focus on three parts of the model.

  • A. The Impulsive System (Gold/Brown)
  • B. The Reflective System (Blue)
  • C. The Interoceptive System (Yellow)
PFC = Prefrontal cortex and Orbital Frontal Cortex Connected to Hypothalamus and Reward Centers
Amygdala-Striatal = midbrain plus Hippocampus
Insular Cortex = Temporal Lobe and Hippocampus

The Three Systems in Balance

When the three parts of the appetite control system are in balance, interoceptive signals from our digestive system signal the brain that we need food or that we should stop eating. We only eat what we need.

The first interoceptive system is in the insular cortex of the temporal lobe. The insular portion of the temporal lobe translates interoceptive signals into awareness, so we notice that we’re “hungry” or full.
The second system, the impulsive system (or reward system), involves many structures such as the hypothalamus, hippocampus, and other midbrain structures. These systems orient us to cues in the environment which are related to our need for food. These structures make us alert to high energy foods such as sugar or fat. Think of this system as a physiological amplifier. It puts us on high alert. We’re prepared to act. We may suddenly flash on the bag of chocolate in the pantry.
The third system is the reflective system. This system involves the frontal cortex. The prefrontal cortex helps us formulate a plan to find food or to stop responding to food cues and thereby stop eating. Our reflective system orders us to get that chocolate and tells us how much chocolate we should eat. Should we eat the whole bag?

Our Brains: Out of Alignment

Study Chen’s model, and you’ll notice the green dashed lines coming from the box at the bottom of the model. These lines show that eating a Western Diet affects all three systems and changes the relationships among them.

The Impulsive System Takes Control

When we eat a Western Diet, the balance between the three parts of the regulatory system is changed for the worse. The impulsive system goes into a maintained state of high alert. It takes more and more fat and sugar to turn the pressure to eat fat and sugar off. Any exposure to food turns the impulsive system on again. For example, we see a picture of a hamburger dripping with fat and cheese on a sign, and we turn into the drive through lane of the fast food franchise as if honing in on an unseen command signal.

The interoceptive system can no longer feed accurate information from the stomach and digestive system to the reflective system. It is now much more difficult to ignore the impulsive system’s demands to find and eat foods loaded with fats and sugars.

We Lose Our Ability to Choose

Our ability to turn off our impulse driven eating and make other choices is gradually eroded when we overeat the Western Diet. We must do what the impulsive system tells us to do. Our ability to see the long-term consequences of our poor food choices is so weak as to be useless. Although our conscious mind knows that eating high caloric food will make us fat and sick, we can’t act on this knowledge.

We’re addicted. We must have fat and sugar enhanced food. We are enslaved.

Think I’m Laying It On A Little Thick?

I’m not exaggerating the dangers of the Western Diet. The science is there. The danger to your brain is real. In the next posts, I’ll describe the many ways in which the Western Diet damages your brain and will double or triple your risk of dementia in your later years.

References

I’m not going to load you down with a bunch of references. Read these six key papers to give you a basic understanding of the key concepts discussed here.

References

Attuquayefio, T., Stevenson, R. J., Oaten, M. J., & Francis, H. M. (2017). A four-day Western-style dietary intervention causes reductions in hippocampal-dependent learning and memory and interoceptive sensitivity. PLoS One, 12(2), e0172645. doi:10.1371/journal.pone.0172645

Chen, R., Li, D. P., Turel, O., Sorensen, T. A., Bechara, A., Li, Y., & He, Q. (2018). Decision Making Deficits in Relation to Food Cues Influence Obesity: A Triadic Neural Model of Problematic Eating. Frontiers in psychiatry, 9, 264. doi:10.3389/fpsyt.2018.00264

Davidson, T. L., Jones, S., Roy, M., & Stevenson, R. J. (2019). The Cognitive Control of Eating and Body Weight: It’s More Than What You “Think”. Frontiers in psychology, 10, 62-62. doi:10.3389/fpsyg.2019.00062

Davidson, T. L., Kanoski, S. E., Walls, E. K., & Jarrard, L. E. (2005). Memory inhibition and energy regulation. Physiol Behav, 86(5), 731-746. doi:10.1016/j.physbeh.2005.09.004

Kanoski, S., Meisel, R., Mullins, A., Davidson, T. L. (2007). The effects of energy-rich diets on discrimination reversal learning and BDNF in the hippocampus and prefrontal cortex of the rat. Behav Brain Res, 182, 57-66. doi:10.1016/j.bbr.2007.05.004

Stevenson, R. J. (2020). Hippocampal-dependent appetitive control is impaired by experimental exposure to a Western-style diet. Royal Society of Open Science. Retrieved from  doi:https://royalsocietypublishing.org/doi/10.1098/rsos.191338

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