Most people know that the initiative of former First Lady Michelle Obama was Let’s Move. One of her goals was to help a new generation of kids grow up knowing the benefits of exercise and a healthy diet and how to apply it to their lives. Instilling such habits when young and being consistent into adulthood can be very beneficial and a vital part of people’s fitness (being fit is not the same as being “skinny” though). However, many people don’t start exercising and eating healthy foods until later in life, specifically as a means to lose weight. This can be an oversimplified understanding of the way obesity works because while these adjustments can definitely help with weight loss, they do not necessarily work for everyone. (Nor should people be expected to lose weight simply because they do not fall into the “Normal” BMI range, but issues with this categorization are a separate topic.) Regardless, a possible explanation for difficulties with losing weight can be found in the brain.
The Science
Within the brain region of the hypothalamus exists a neuronal circuit called the melanocortin system with two subsets of neurons: AgRP and POMC. At homeostatic functioning, insulin and leptin inhibit AgRP neurons within this system to decrease energy intake and instead activate POMC neurons to increase energy expenditure. However, an HFD (high fat diet) can significantly reduce hypothalamic sensitivity to insulin (even after only three days) and may contribute to the development of insulin and leptin resistance. This resistance may be restored by unsaturated fatty acids like omega-3.
However, saturated fatty acids can trigger inflammatory signaling which, when prolonged, can lead to cell death in the hypothalamus, specifically in POMC neurons. HFDs and overnutrition can also cause oxidative stress in neuronal cells and consequently metabolic syndrome. An interesting fact is that hypothalamic inflammation, and thus possibly metabolic dysregulation, occurs before significant weight gain, meaning that once weight gain does occur, it might already be very difficult to lose it again and restore the original homeostasis in the brain.
Other Issues
This science explains why it may be more difficult for some people to lose weight. But if overnutrition or high fat diets can induce metabolic dysregulation and issues surrounding obesity, why do we consume “unhealthy” foods anyway?
Well, there are a number of possible reasons… Sometimes we indulge in unhealthy food simply because it tastes good and we crave it. Sometimes we are in a rush and only have twenty minutes to eat, so we buy fast food. But oftentimes, there is more to it than that, especially in different segments of the population.
Food availability and financial insecurity are two factors that can influence what types of food a person ends up consuming. Many people in the United States live in poverty or financial insecurity, and when unhealthy processed food is cheaper than healthy fresh food, people are more likely to purchase the box of mac-‘n-cheese or canned beef stew instead of fruits and vegetables or chicken breast. A further issue we encounter in connection to this, is that impoverished areas are often considered to be “food deserts”, meaning that there is less access to fresh foods because it is less available compared to urban or suburban settings. Therefore, even if people wanted to make healthy choices in terms of their diets, it may simply not be possible or feasible for them. This is where policies, incentives, or government-run programs may be beneficial. Let’s Move was a first step (the program also attempted to improve accessibility and affordability of healthy foods), but there is more to be done.
Bacon wrapped steak, bacon wrapped burger, bacon wrapped pork chop so why not a bacon wrapped brain? Literally anything can be wrapped in bacon. Even though bacon is delicious, along with all of the other fatty foods we eat, we definitely shouldn’t eat it with every meal. High fat diets have been linked to brain damage, type 2 diabetes, insulin resistance and more. This is why doctors across the country and even the world, are telling us to stop eating fatty foods frequently. Yes, there are good fats and bad fats, but constantly consuming good or bad harms your body. In fact, it may actually be your brain that is taking the brunt of the high fat diet.
hypothalamus. This binds to a toll-like receptor (TLR) which is a protein that plays a key role in the immune system. When we think of the immune system, we typically think of a cold and how the body reacts by producing more mucous, a sore throat, and how it pretty much attacks itself. This sort of happens in the brain, but on a much smaller level. In the brain, IKK is produced. IKK is a response to inflammation which triggers NF-kB. This then makes its way to the nucleus to induce transcription. Here, it triggers more cytokines called TNF-alpha which bind to more receptors. This creates a negative feedback loop that is hard to stop because all you want to do is eat because the receptor is constantly saying “KEEP EATING!”. IKKβ is the big red light blaring this, which increases food intake, body weight gain, and also interrupts insulin and leptin signaling. So, different than making mucous, it makes you want to eat more and inflames your neurons. Inflammation in a neuron is actually the wearing down of myelin and the wearing down inside the neuron itself. This wearing down effects the endoplasmic reticulum, and causes oxidative stress. It may seem like this is never ending, but there are solutions.
symptoms that lead to an increase in the risk of developing Type 2 Diabetes, Cardiovascular Disease, and stroke. The figure is a good graphic of what components are involved with metabolic syndrome. Having even one component of metabolic syndrome can increase your risk of development of a serious condition. About 1/3 of adults in the United States have metabolic syndrome. One of these components is critical in the hypothalamic inflammation that is seen in obesity, insulin signaling. https://www.mayoclinic.org/diseases-conditions/metabolic-syndrome/symptoms-causes/syc-20351916
lazy and eating food that is bad for them. While factors such as eating habits, exercise, and screen time all contribute to a person’s weight, so do medications, chronic illnesses, socioeconomic status, and access to healthy foods. Genetic predisposition has also recently been shown to play a major role in a person’s weight. What many people don’t know is that chemical changes in the brain are partially, if not largely, responsible for obesity and can be induced by outside factors.
