The number of individuals with obesity has grown significantly in recent decades. This is mainly due to increased consumption of highly processed, calorie-dense foods and a decline in physical activity due to modern, sedentary lifestyles. The World Health Organization has declared obesity to be an epidemic, affecting over one billion people around the world. A mass body index of 30 or more is considered to be obese, and a poor diet or insufficient exercise is often seen as the cause. This chronic condition has been known to increase the risk of illnesses such as diabetes, heart attacks, heart disease, Alzheimer’s disease, and cancer. The brain is a huge factor in the development of obesity as it regulates insulin levels. Poor eating habits can have negative impacts on brain health, which can be linked to impaired cognitive function, among other issues.

The brain plays a pivotal role in the development of obesity and type 2 diabetes. A study conducted by the University Hospital of Tübigen consisted of 29 male volunteers of average weight. They were split into two groups: for five days in a row, the first group had to add 1500 kcal from high-calorie, ultra-processed snacks into their regular diet, while the control group did not consume these extra calories. An examination completed directly after the experiment showed that for those in the experimental group, fat content in the liver increased. Also, lower insulin sensitivity in the brain persisted for over a week after returning to their regular diet. In healthy individuals, moderate insulin intake may result in an appetite-suppressing effect in the brain. However, in people with obesity—who may consume insulin in excess—insulin may no longer regulate eating behavior. This results in insulin resistance, which can be defined as when one’s body produces more insulin in order to keep up with chronically high insulin intake. This high insulin level can trick the body into wanting to consume more sugar. This means that even short-term consumption of highly processed, high-calorie foods can lead to reduced insulin sensitivity, creating a cycle that’s hard to break.

Obesity can have numerous negative impacts on brain health, along with other health risk factors. The article, Neuroanatomical correlates of cognitive aging: Evidence from structural magnetic resonance imaging, published in 1998 by the Neuropsychology Journal, established that as one ages, their brain volume decreases. However, in 2010, the Boston University School of Medicine found a link between obesity and brain volume. They conducted a study with 733 adults and found that body mass index (BMI) and total brain volume were inversely related. This drew the conclusion that people with more body fat had lower brain volume. Furthering the study, Neurobiology of Aging compared brain scans of 500 adults. They observed that white matter, a network of nerve fibers in the brain, was lower in obese people. Therefore, being obese appeared to increase brain age by ten years. As brain volume decreases, one is more likely to have problems with thinking and memory.

According to the State of Childhood Obesity, more than 22% of young people, ages 2 to 19, are obese. The researchers found that obese children had less control over their food consumption compared to healthy children, which led to overeating. Regardless of age, poor eating habits can result in changes to one’s brain. The Journal of Neuroscience published a study of how the striatum in the brain was less active, particularly in women who gained weight. The striatum plays a role in reward perception when eating. Depending on the type of food one eats, the pleasure received is a result of dopamine being released. The study concluded that people who are obese have a lower signalling capacity, meaning they need to eat more food in order to feel the same sense of reward.

Obesity is not only caused by a poor diet and insufficient exercise, but is also linked to brain function, and what results when it is exposed to a significant increase in insulin. Obesity can be a dangerous health condition, and it increases the risk of other chronic health conditions. For those struggling, it is never too late to make a change. A healthy diet can be extremely beneficial during the weight-loss process. However, it is important to remember that weight loss differs for everyone—the number of calories burned or gained daily depends on a person’s gender and age. Fruits, vegetables, whole grains, and lean meats are a great substitute for processed foods. Exercise is also important for maintaining a healthy lifestyle, and how much one should get is dependent on their age. Making small, consistent changes can promote improvements in both physical health and brain function, allowing for long-term wellbeing.