Obesity: a disease, not a lifestyle choice

Obesity treatment is undergoing a radical transformation, fueled by the recognition that both biological and psychosocial factors play a role.

This understanding is shaping new, more effective and compassionate strategies for treatment and care.

The medical basis for defining obesity as a disease

The WHO defines obesity as abnormal or excessive fat accumulation that increases health risks, typically measured using the Body Mass Index (BMI). A BMI of 30 or higher is considered obese. While BMI is easy to calculate, it fails to distinguish between muscle and fat. Other methods, such as waist circumference, skinfold thickness, and advanced scans, offer better accuracy but aren’t always accessible.

Genetics play a critical role in obesity, influencing factors such as metabolism and hormone regulation. Studies involving twins, families, and adoptees indicate that 40-70% of obesity variance is attributable to genetics. Additional evidence shows that genetic predisposition, metabolic processes, and hormonal imbalances significantly contribute to obesity, reinforcing its classification as a disease.

Medical experts and bodies, including the Centers for Disease Control and Prevention (CDC), the American Medical Association, the European Medical Association, the World Obesity Federation, and the WHO, support defining obesity as a disease.

Recognising obesity as a disease emphasises its complexity and the need for comprehensive treatment and prevention strategies at both individual and societal levels.

Why obesity is a disease

Obesity can disrupt normal bodily functions, lead to significant health complications, and is marked by distinct symptoms such as excessive body fat, metabolic alterations, and heightened health risks. These characteristics align with disease pathology rather than mere lifestyle consequences. 

Let's delve deeper into the reasons why obesity is a disease:

1. Genetics

Studies have shown that genetics play a significant role in obesity. Investigators recently combined and re-analysed data from 54 studies including about 240,000 people. They found that people who carried the obesity-promoting FTO gene variant had a 23% higher risk of obesity than those who didn’t. While no single genetic cause can be identified in most obese individuals, genome-wide association studies since 2006 have found over 50 genes associated with obesity.

2. Environmental influences

Our environment heavily influences our eating and activity patterns. Urban areas often lack spaces for physical activity, and fast food outlets are more accessible than fresh produce markets. This is backed up by solid data. When Transport for London removed ads for fast food from public transport in 2019, there were 94,867 estimated fewer occurrences of obesity, 2,857 cases of diabetes prevented or delayed, and 1,915 fewer cases of cardiovascular disease.

3. Psychological aspects

Mental health is another crucial factor. Conditions such as depression and anxiety or stress can lead to weight gain. Emotional eating is a common response to stress. The relationship between mental health and obesity also goes both ways - obesity can lead to poor mental health, and vice versa. Addressing obesity requires a holistic approach that includes psychological support. 

Negative stigma towards weight can trigger behaviours like overeating and exercise avoidance. This stigma even affects medical care, where patients often report feeling judged by their healthcare providers, making them less likely to achieve weight loss. This is another reason why defining it as a disease is helpful in patient care. 

4. Hormonal imbalances

Hormonal imbalances can also cause obesity. Conditions like hypothyroidism and polycystic ovary syndrome (PCOS) affect metabolism and can lead to weight gain. These are medical conditions that require treatment, not judgement. Ignoring the biological basis of obesity furthers stigma and delays necessary medical interventions.

5. The role of metabolism

Metabolism varies from person to person. Some people have a naturally slower metabolism, which means they burn calories more slowly. This metabolic rate is influenced by several factors, including age, sex, and genetic makeup - all factors out of your control. 

The numan take

Obesity is a multifaceted disease, not a simple lifestyle choice. Viewing it as a lack of personal responsibility ignores these complexities and perpetuates harmful stigma.

Recognising obesity as a disease is crucial for establishing a more supportive healthcare system and ultimately achieving a healthier society.