Obesity and the Brain: A Vicious Cycle of Cravings, Inflammation, and Cognitive Decline

How excess body fat rewires the brain and drives unhealthy eating—and solutions.

Flotsam/Shutterstock

Obesity is a burden on the body—it also reshapes the brain. While its physical toll is well-known, mounting research shows that excess body fat changes the brain, affecting how we think, feel, and understand.

The connection is made worse because calorie-rich, highly tasty foods can hijack our brain’s reward system, making them almost impossible to resist.

A Vicious Cycle

The relationship between obesity and the brain goes beyond physical changes and is fueled by a continuous, self-reinforcing loop, in which obesity stems from certain behaviors while also reinforcing and perpetuating them.

Our brains are wired to find pleasure in calorie-dense foods, a deeply ingrained evolutionary trait that once served us well in times of scarcity. However, in today’s abundant food environment, this wiring becomes a problem.

Foods high in sugar, fat, and salt trigger a strong release of dopamine in the brain, create a powerful sense of pleasure, and reinforce the desire to keep eating them. Ultra-processed foods are designed to overstimulate this reward pathway, effectively hijacking our natural satiety signals and making it harder to know when we’ve had enough.

Research also suggests that obese people are more likely to make riskier choices in situations involving calculable risks, particularly when the potential downside is low. This might explain certain food choices, even when the health consequences are known.

Adding fuel to this cycle is the relentless marketing of unhealthy foods. The average person is exposed to about 2,000 ads for food every day, Dr. Eric Akin, a neurosurgeon who reversed his prediabetes, told The Epoch Times. Most of those ads are for very calorie-dense, nutrient-poor, sugar-laden foods.

“They have got you at both a subconscious level and a metabolic level if you’ve been eating poorly for a while,“ Akin said. ”The leverage is in their favor.”

Obesity significantly affects executive functions, with self-control being particularly undermined. Reduced ability to resist immediate gratification hinders healthy food choices despite an awareness of long-term consequences. This is partly because of dysfunction in the prefrontal cortex, a key brain region for inhibitory control and decision-making.

Over time, overeating can dull the brain’s response to pleasure from food, making it harder to feel satisfied. A 2025 animal study published in Nature demonstrated that high-fat diets lower a brain chemical linked to food reward called neurotensin, potentially driving further eating.

Reward deficiency syndrome can create a cycle of eating more to feel satisfied. To achieve the same level of pleasure, people might seek out even more intense and often unhealthier food experiences, further reinforcing eating patterns and contributing to continued weight gain.

The chronic low-grade inflammation associated with excess body fat can also reach the prefrontal cortex, impairing its function. Chronic inflammation may make it more difficult to exert willpower over food choices and resist cravings. This creates a cycle in which cognitive impairment leads to poor food choices that further exacerbate weight gain and the associated cognitive consequences.

Hormonal imbalances in obesity further contribute to this cycle. Leptin, a hormone released by fat cells, signals the brain when the body has had enough to eat. But in people with excess body fat, the brain can become resistant to leptin, meaning that it fails to register those satiety signals. This leads to a constant feeling of hunger, disrupted reward processing, and greater susceptibility to overeating.

Insulin resistance, another common consequence of excess fat, creates blood sugar fluctuations that may trigger hunger, particularly for high-carbohydrate and sugary foods.

Akin said the brain’s hunger-satiety system is complex and sensitive to our diet. Frequent insulin spikes and blood sugar crashes, often from poor eating, can overstimulate the hunger center, leading to frequent feelings of hunger even when the body has enough calories.

Body Fat Alters the Brain

Excess body fat can reshape the brain in different ways.

A growing body of research indicates that excess body weight may affect brain structure. Studies show that overweight and obese people tend to have a smaller total brain volume, which may make the brain appear older than it actually is.

A 2019 study published in Neurology found that having more body fat, especially belly fat, is linked to having less gray matter in the brain, which controls movement, memory, and emotions. The study also found evidence linking obesity to smaller volumes in specific brain areas involved in behavioral control and reward processing, areas thought to be related to appetite regulation. However, which comes first remains unknown.

A March study published in JAMA found that a smaller waist-to-hip ratio in middle age is linked to healthier brain structure and function in older age, specifically working memory and executive function. The connection seems to be partly explained by the health of the brain’s white matter. Obesity may reduce white matter integrity, impairing communication between brain regions. The findings suggest that what you eat and how much belly fat you have in your 40s, 50s, and 60s can affect your memory center and overall thinking skills when you’re in your 70s.

Research also shows that reduced blood flow in the brain is correlated with higher body weight, which has been linked to an increased risk of cognitive decline and dementia.

The cognitive consequences of obesity are often intertwined with emotional and mental well-being. Those who are overweight or obese may experience higher rates of anxiety, depression, and low self-esteem. Existing in such emotional states can further impair cognitive functions such as attention, memory, and executive control, creating a complex dynamic between physical health, mental health, and cognitive abilities.

“Emerging evidence points to dysregulated brain energy production as a contributing mechanism for many psychiatric and other brain-based conditions,” Dr. Bret Scher, a board-certified cardiologist and expert in metabolic health, told The Epoch Times via email.

Scher said he believes that there is a strong connection between metabolic dysfunction and mental health disorders, noting that scientific support for this connection is growing.

He cautioned against blaming individuals for their health challenges.

“It isn’t someone’s fault,“ he said. ”But it is empowering to know that by improving our metabolic health, we may be able to improve our mental health.”

Mental health, he noted, involves a complex interplay of genetics, gene expression, and environmental influences.

These brain-related effects not only affect adults, but can also start early and affect adolescents—with lasting consequences.

Risk for Growing Children

Childhood is a critical time for brain development, especially in areas responsible for executive function and memory. During this stage, the brain undergoes rapid growth and is highly sensitive to external influences. While the developing brain’s plasticity allows for learning, it also increases vulnerability to harmful influences, such as chronic inflammation and metabolic imbalances associated with obesity.

As Scher warned, this early metabolic dysfunction could impair brain function during crucial developmental stages, potentially leading to lifelong issues such as poorer general cognition, brain dysfunction, and an increased risk of cognitive decline with aging.

Executive functions are vital for academics, self-regulation, and decision-making. Deficits can hinder a child’s ability to learn, control impulses (including food choices), and plan for the future.

Some research suggests that early obesity and insulin resistance can trigger irreversible epigenetic changes, altering how genes are expressed and contributing to cognitive problems later in life. Childhood obesity is also linked to higher rates of anxiety, depression, and low self-esteem, which can further interfere with learning and social skills.

“I fear a lifetime of insulin resistance may predispose children not only to psychiatric symptoms, but also to early cognitive decline,” Scher said. “We don’t have much research on this in kids, but unfortunately, we seem to be running an ongoing real-world experiment right in front of our eyes.”

While all of the above is concerning, research suggests that the negative impacts of obesity on a child’s brain health may be reversed or improved with weight loss and lifestyle changes, especially because the brain is still developing. Early intervention and prevention are key to protecting children’s brains.

Break the Cycle

Understanding the detrimental effects of obesity on the brain highlights the importance of taking proactive steps to break the cycle in adults and children. The multifaceted connection between body fat and brain function might seem overwhelming, but the good news is that positive changes are possible. By understanding everything at play, we can strategically intervene.

Evidence suggests that losing weight and maintaining the loss can initiate a reset of the brain’s reward system. As the weight drops, particularly through gradual and sustainable methods, there is potential for less intense urges for unhealthy, hyperpalatable foods, likely because of an increased sensitivity to natural fullness signals and a decreased responsiveness to the dopamine surges these foods trigger.

Allowing the brain time to adapt to healthier patterns through gradual changes is crucial for long-term success and can help foster a shift in preference toward healthier, more nourishing foods.

However, Scher said, “One of the biggest misconceptions is that weight loss equals health.”

He said the focus should be on weight loss strategies that maximally improve metabolic health, are sustainable, and directly benefit mental well-being, noting the positive impact of low-carb and ketogenic interventions.

Actively working to strengthen self-control related to food choices can help break the cycle. Mindful eating, which involves paying close attention to hunger and fullness cues, can increase awareness and reduce impulsive eating. Avoiding foods that trigger continual eating and minimizing exposure to unhealthy options can also lessen temptation. Adopting healthier habits, including regular physical activity and a balanced diet, may also improve function in the prefrontal cortex, the brain region vital for self-control.

“Self-control is made much more difficult when we eat foods that trigger the reward centers of our brain and don’t provide the nutrients and satiety that we need,” Scher said.

Low-carb and ketogenic diets have been shown to reduce hunger and cravings, and thus make self-control much more possible, he noted.

Regular physical activity is a powerful tool in disrupting the loop between obesity and brain function. Beyond its direct benefits for weight management and metabolic health, exercise supports overall brain function, including mood regulation. By helping to reduce stress and anxiety, which can often trigger cravings for comfort foods, and by positively influencing hormonal functions such as insulin sensitivity, physical activity further contributes to fewer appetite spikes and better regulation.

Akin said intense exercise triggers a significant release of interleukin 10, an anti-inflammatory molecule highly beneficial for the brain that he calls the “fountain of youth.” He also touts resistance exercise as what’s most likely to keep you metabolically flexible, especially in your later years.

“Exercise is the best thing to do for your brain,” he said.

Feed the Brain Better

Adopting a balanced diet plays an important role in stabilizing blood sugar levels, which can significantly reduce the intense cravings often associated with processed and sugary foods. Unprocessed foods help you feel fuller for longer and reduce the urge to overeat. Consistent, balanced meals help steady hormones, curb cravings, and support a healthier relationship with food.

Scher sees dietary changes as the biggest factor in supporting physical, cognitive, and emotional well-being. He suggests focusing on whole foods and removing high-calorie and high-reward foods, which are usually ultra-processed ones.

“Perhaps the most impactful dietary change is entering a state of ketosis, since this provides the brain with a different fuel source in the form of ketones,“ he said. ”This can bypass the insulin resistance and allow the brain to once again efficiently transform energy.”

The Cognitive Effects of Obesity

If you’re concerned about how excess weight might be affecting your thinking, Akin listed specific signs to watch for: “If you’re having trouble doing simple math in your head. If you’re trying to precisely calculate a 15 or 20 percent tip and you’re struggling to do that and you have to whip out paper and pen to make it happen, that’s a sign you could be having a problem.”

Occasional memory slips, such as forgetting a name or where you put your phone, are normal and have many possible causes, he said. However, consistently struggling on a daily basis or having trouble with simple mental math in your 20s or 30s might suggest a more serious issue.

To further complicate the relationship between obesity and brain health, excess body fat is not the sole clear-cut indicator of cognitive issues. People with a healthy body mass index can experience repercussions, so staying on top of the subtle signs is key and can offer a nudge to get your bloodwork done, regardless of what the scale says.

“[Cognitive consequences] may not be associated with [being overweight and obese] per se, but more with the accompanying metabolic dysfunction,” Akin said.

If you’re wondering if you can regain cognitive capacity if you lose weight, Akin said he toes the line between caution and hope.

“As with everything, there’s always a point of no return,“ he said. ”But there is certainly a restorative capacity. A lot of people find that their cognitive function greatly improves once they finally start making the change in behavior and food selection.”