Myths and facts about obesity

Myth: “Obesity is just about calories”

‍It can sound simple: eat less, move more, and everything will sort itself out. But obesity is far more complex than that. The body is regulated by the brain, hormones and genetics, and these factors influence how hunger, satiety and energy expenditure are controlled.

When calorie intake is reduced, the body often responds by lowering energy expenditure in various ways and increasing hunger. This happens because the body strives to maintain its previous weight level and biologically compensates to counteract weight loss. As the body becomes smaller, it also requires less energy, meaning energy intake may need to be reduced even further.

The body conserves energy by reducing spontaneous movement, known as NEAT (Non-Exercise Activity Thermogenesis) – movements such as gesturing, walking around or fidgeting. Reduced energy intake often leads to fatigue, which in turn can unconsciously reduce physical activity.

The body can also lower energy expenditure by reducing heat production. Hunger often increases significantly and unconsciously, contributing to gradually larger portions and stronger cravings for more energy-dense foods.

“Obesity is not a real chronic disease”

‍Obesity is now internationally recognised as a chronic and complex disease. This means the condition is not only about body weight, but about health. Its complexity lies in the fact that it is influenced by a combination of genetics, hormones, lifestyle and environment. The disease cannot be explained solely by lifestyle choices.

Defining obesity as a disease is therefore not about “medicalising” weight, but about understanding that the condition affects multiple organ systems and can lead to significant medical consequences. Living with severe overweight or obesity increases the risk of a range of comorbidities, including type 2 diabetes, cardiovascular disease, sleep apnoea, non-alcoholic fatty liver disease (NAFLD), osteoarthritis, hormonal disturbances, reduced fertility and certain cancers. The condition can also affect psychological wellbeing and quality of life.

Viewing severe overweight and obesity as chronic diseases requires the right type of support: structured follow-up, individualised treatment and long-term, evidence-based interventions. It also means shifting the focus away from blame and oversimplified advice towards a medical perspective, where patients receive the same respect and care as those with other chronic conditions.

Just as we would not tell a person with asthma to “breathe better” or someone with high blood pressure to “think positively”, obesity should be treated with professional care and the same seriousness as other chronic diseases.

“A large weight loss is required to see health benefits”

‍It is easy to believe that only major weight changes matter, but research shows otherwise. Even modest changes – as little as a 5–10 per cent reduction in body weight – can lead to clear health benefits, such as improved blood glucose control, better triglyceride levels and lower blood pressure.

Further weight loss can provide additional benefits, including further improvements in blood sugar, blood pressure and blood lipids, reduced fat accumulation in the liver and a lower risk of type 2 diabetes. Many people also experience better sleep, increased energy and reduced strain on the joints.

What matters most is not reaching a “perfect” weight, but giving the body better conditions to function well – and that can begin long before the scales show large changes.

“If you are physically active, you won’t develop obesity”

‍It is easy to imagine that physical activity alone can prevent or treat obesity, but human biology is not that simple.

Physical activity is one of the most important interventions for overall health. It strengthens the cardiovascular system, preserves or increases muscle mass and has a clearly positive effect on mental wellbeing. When it comes to body weight, however, exercise plays a smaller role than many people assume.

Research shows that exercise alone rarely leads to substantial weight loss. This is partly due to the body’s ability to biologically compensate: increased exercise may lead to reduced resting energy expenditure, increased appetite or reduced spontaneous daily movement as compensation for higher effort. These mechanisms limit total energy expenditure and mean the impact on body weight is often smaller than expected.

This does not mean that exercise has no role in obesity treatment. On the contrary, it helps explain why many people do not lose weight despite regular physical activity, and why exercise should be viewed as part of a broader treatment strategy.

Exercise does, however, have a protective effect against weight gain. Physically active individuals generally find it easier to maintain a stable weight over time.

It is important to remember that exercise has major health benefits regardless of weight. Regular movement reduces the risk of cardiovascular disease, type 2 diabetes, mental ill health and functional impairment – even in people living with obesity. Exercise should therefore be seen as a central and long-term investment in health, regardless of weight.

“Overweight and obesity are just about lack of willpower”

‍The idea that obesity is caused by poor willpower is a deeply rooted myth – and one that is not supported by modern medical knowledge. Research shows that obesity is a chronic, biologically regulated disease in which the brain, hormonal systems and genetic factors all play a role. It is therefore not about simply “deciding” to change, but about complex physiological processes that strongly influence body weight.

Genetic factors can affect how the body’s systems for appetite, energy expenditure and fat storage function. In some individuals, these regulatory mechanisms are altered, causing the body to “defend” a higher weight. In addition to genetics, many other factors influence the risk of weight gain, including stress, sleep deprivation, certain medications, hormonal changes and the surrounding environment. Conditions during pregnancy and early childhood can also affect long-term obesity risk, for example through hormonal influences or early dietary and lifestyle patterns.

This does not mean that lifestyle is unimportant, but it explains why willpower alone cannot overcome biological mechanisms. Viewing obesity as an individual “choice” is therefore both misleading and harmful. Such a perspective increases guilt and stigma, which can make both treatment and wellbeing more difficult. Like other chronic diseases, obesity needs to be met with understanding, evidence-based care and long-term support.

“Medical treatment is cheating”

‍This myth is often based on a misunderstanding of what obesity medications actually do. In reality, these treatments are not about “replacing lifestyle change”, but about creating conditions that make more conscious food choices possible, leading to reduced energy intake and weight loss. New medications affect signalling between the gut and the brain, allowing hunger and satiety to function more like they do in people without obesity.

It is not a shortcut. It is not cheating. It is science. Large clinical trials have shown that these medications can lead to sustained weight loss of 15–20 per cent of body weight, while also improving several health markers such as blood pressure, blood glucose and cholesterol levels. Many people also describe a new sense of freedom in everyday life, with less focus on food, better sleep and increased energy.

Medical treatment works best as part of a comprehensive programme that includes support for lifestyle habits, physical activity and mental health. It is about guiding patients to the right support and treatment, and giving the body the help it needs to function properly.

Obesity – increased risk of other diseases

Overweight and obesity are major global public health challenges. According to the World Health Organization, increasing numbers of people live with overweight or obesity, which raises the risk of conditions such as type 2 diabetes, high blood pressure and cardiovascular disease. Understanding causes, measurement and treatment is therefore essential.

Definition and measurement

Obesity is defined using Body Mass Index (BMI). A BMI of 30 or higher is classified as obesity, and 25–29.9 as overweight. However, BMI does not provide the full picture, as it does not distinguish between muscle and fat mass, nor does it account for where fat is distributed in the body – which is important for health risk assessment. Other measures, such as waist circumference and body composition, can therefore be useful to obtain a more comprehensive understanding of health.

Medical treatment for obesity

Medical treatment can be a highly effective complement to lifestyle changes for people living with obesity. Modern weight-loss medications help regulate hunger and satiety by enhancing the body’s natural hormonal signals that control appetite. They help you feel full sooner, reduce cravings and promote more stable blood glucose levels, making it easier to reduce energy intake in a sustainable way.

These medications should always be combined with support for lifestyle changes and be monitored by healthcare professionals for best results. In Europe, several approved medications are available and may be prescribed when appropriate, particularly for individuals with a BMI of 30 or higher, or BMI ≥ 27 (overweight) in the presence of at least one weight-related comorbidity (such as high blood pressure, elevated blood lipids, obstructive sleep apnoea, cardiovascular disease, prediabetes or type 2 diabetes).

Support and conversation

Support from doctors, dietitians, psychologists or group programmes can facilitate change for people with overweight or obesity. Sharing experiences and receiving help with motivation are important for long-term, sustainable change.

Preventive lifestyle

Preventing overweight and obesity involves a balanced diet, physical activity and awareness of factors such as genetics and life circumstances. Early support and gradual changes play an important role in long-term health.