What Causes Obesity? More Science Points to the Brain

What Causes Obesity? More Science Points to the Brain

Obesity is a complex condition that affects millions of people worldwide. While it is commonly believed that obesity is solely caused by overeating and lack of physical activity, recent scientific research suggests that the brain plays a significant role in the development of obesity. In this blog post, we will explore the various factors that contribute to obesity and how the brain is involved.

1. Genetics and Epigenetics

Research has shown that genetics play a role in determining a person's susceptibility to obesity. Certain genes can affect appetite, metabolism, and fat storage, making some individuals more prone to gaining weight. Additionally, epigenetic factors, such as environmental influences on gene expression, can also contribute to obesity.

2. Hormonal Imbalances

Hormones play a crucial role in regulating appetite and metabolism.¹ Imbalances in hormones like leptin, ghrelin, insulin, and cortisol can disrupt the body's natural weight regulation system. For example, leptin, known as the "satiety hormone," signals the brain when the body has had enough food. However, in obese individuals, the brain becomes resistant to leptin, leading to overeating.

3. Brain Reward System

The brain's reward system, which is responsible for regulating pleasure and motivation, can also contribute to obesity. Studies have shown that certain foods, particularly those high in sugar and fat, can activate the brain's reward system in a way that is similar to drugs of abuse. This can lead to overconsumption and the development of food addiction.

4. Stress and Emotional Factors

Chronic stress and emotional factors can significantly impact eating behaviors and contribute to obesity. When faced with stress, the brain releases cortisol, a hormone that can increase appetite and promote the accumulation of fat, especially around the abdominal area. Emotional factors, such as depression and anxiety, can also lead to emotional eating and weight gain.

5. Food Environment and Marketing

The food environment and marketing strategies also play a role in the development of obesity. The availability of high-calorie, processed foods, coupled with aggressive marketing techniques, can influence food choices and contribute to overeating. Additionally, the increased portion sizes of meals and snacks in restaurants and fast-food chains² have also been linked to obesity.


While overeating and lack of physical activity are important factors in the development of obesity, it is clear that the brain plays a significant role in this complex condition. Understanding the various factors that contribute to obesity, including genetics, hormonal imbalances, the brain's reward system, stress, and the food environment, can help inform strategies for prevention and treatment. By addressing the underlying causes of obesity, we can work towards a healthier future for individuals affected by this condition.


1. Obesity and hormones - Better Health Channel

2. Large restaurant portions a global problem, study finds | ScienceDaily

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