The Truth About Weight and Health

For decades, we’ve been told that weight equals health. That maintaining a BMI below 30 is necessary to avoid disease. That losing weight is the key to living longer and feeling better.

But what if everything we’ve been taught about weight and health is based on flawed science and outdated beliefs?

What if the obsession with weight wasn’t really about well-being, but about control, bias, and oversimplified medical models?

The reality is that weight is not a reliable measure of health—and when we dig into the history of how weight became the focus of modern medicine, the cracks in the system become glaringly obvious.

By understanding:

• The origins of using weight as a health marker,

• The flaws in the BMI system, and

• How medical weight bias harms fat people,

  you can begin to reject diet culture with confidence—knowing that your health is not dictated by a number on the scale.

1. Where Did the Idea of Weight as a Health Marker Come From?

Modern medicine treats weight as one of the biggest indicators of health—but this idea is relatively new and built on misguided historical beliefs rather than solid science.

Early Medical Views on Weight

Before the 20th century, larger bodies were often associated with strength, fertility, and health. Thinness was linked to malnutrition and illness, not health and fitness.

However, as industrialisation led to more sedentary lifestyles, doctors and social scientists began to view body size as a moral issue rather than a medical one. Being thin became associated with self-control, while fatness was increasingly seen as a sign of laziness and poor character—not necessarily poor health.

The Role of Insurance Companies

The first major push to link weight and health came not from doctors, but from life insurance companies. In the early 1900s, insurance companies began using height and weight charts to assess policyholders' life expectancy. These charts were never intended to measure individual health—but over time, doctors adopted them as medical guidelines, reinforcing the belief that weight directly affects longevity.

Ancel Keys and the Birth of BMI

In 1972, American physiologist Ancel Keys popularised the Body Mass Index (BMI) as a way to measure body fat across populations. However, BMI was:

• Never designed to assess individual health—it was meant for large-scale studies.

• Based on white, European male bodies, ignoring diversity in race, sex, and genetics.

• Not validated by modern medical standards, yet it was widely adopted as a diagnostic tool.

By the 1990s, governments and public health organisations began using BMI to classify “obesity” as a medical crisis, despite major flaws in its methodology.

2. The Flaws in the Science of BMI and Weight-Based Health

The argument that people should maintain a BMI below 30 to stay healthy is based on incomplete, misleading, and outdated science. Here’s why:

BMI Is Not a Measure of Health

BMI is a crude calculation that divides weight by height squared. It does not measure:✅ Muscle mass✅ Fat distribution✅ Metabolic health✅ Fitness levels

A high BMI does not automatically mean a person is unhealthy, just as a low BMI does not guarantee good health. Many elite athletes, bodybuilders, and physically fit individuals are classified as "overweight" or "obese" under BMI standards.

The "Obesity Paradox"

Research has repeatedly shown that being in the “overweight” or “obese” BMI categories is not always harmful. Studies on the “obesity paradox” show that in many cases, people with a higher BMI actually have lower mortality rates and better recovery outcomes than those in the “normal” weight range.

For example:

• Older adults with a BMI in the "overweight" category live longer than those in the "normal" range.

• Fat people have better survival rates after major surgeries, heart attacks, and strokes compared to thinner patients.

• Some studies suggest that higher body fat may offer protective benefits against certain diseases.

Correlation Does Not Equal Causation

Much of the research linking weight to disease is correlational, not causal. In other words, just because fat people have higher rates of certain illnesses does not mean fatness causes those illnesses.

Other factors—such as genetics, socioeconomic status, stress, discrimination, and access to healthcare—play a far bigger role in health outcomes than weight alone.

3. The Impact of Medical Weight Bias on Fat People

One of the most damaging consequences of diet culture and weight-based health policies is medical weight bias—the discrimination fat people face in healthcare settings.

What Is Medical Weight Bias?

Medical weight bias occurs when healthcare professionals:

• Assume a patient's health problems are due to their weight.

• Prescribe weight loss as a solution for all ailments.

• Dismiss symptoms in fat patients that would be taken seriously in thinner patients.

• Delay or deny medical treatment until weight loss is achieved.

  
  

How Weight Bias Harms Fat Patients

Weight bias in medicine has real, measurable consequences for fat patients, including:

🚨 Misdiagnosis and Delayed Treatment – Doctors often blame symptoms on weight rather than investigating other causes. Many fat patients have had serious conditions (cancer, autoimmune diseases, infections) dismissed as "weight-related" and left undiagnosed for years.

🚨 Avoidance of Medical Care – Many fat people avoid going to the doctor due to past experiences of shame and stigma, leading to poorer health outcomes not because of their weight, but because of discrimination.

🚨 Unethical Weight Loss Advice – Instead of offering practical, evidence-based treatment, doctors often prescribe weight loss—even when it's irrelevant or harmful to the patient’s actual condition.

🚨 Psychological Harm – Being told your body is a problem leads to disordered eating, depression, and anxiety, all of which negatively impact overall health.

Challenging Medical Weight Bias

If you’ve ever been dismissed by a doctor because of your weight, you are not alone. To challenge weight bias in healthcare:

✅ Advocate for yourself – Ask your doctor to treat your symptoms, not your weight.

✅ Seek weight-inclusive healthcare providers – Look for doctors who practice weight-neutral medicine.

✅ Educate yourself – Understand that weight loss is not a cure-all solution.

Final Thoughts: Why You Can Reject Diet Culture With Confidence

The belief that thin equals healthy and fat equals unhealthy is based on faulty science, outdated medical models, and systemic bias—not objective truth.

When you realise:

📌 Weight is a poor indicator of health.

📌 BMI is an outdated and inaccurate measurement.

📌 Weight bias in medicine harms, rather than helps, fat people.

...it becomes much easier to reject diet culture and embrace a weight-inclusive approach to health.

Your body is not the problem—diet culture is.

Instead of chasing an arbitrary weight goal, focus on holistic health habits—nourishment, movement, sleep, stress management, and mental well-being.

Health is not about being thin. It’s about taking care of your body, no matter its size.

Need More Help UnWiring Your Brain from Diet Culture?

Contact Alison at The Appetite Club to get down to a neural level required to free yourself enough to embrace intuitive eating.