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Obesity is a medical diagnosis that involves an unhealthy excess of body fat. It increases the risk of diseases such as type 2 diabetes, cardiovascular disease, sleep apnea and some forms of cancer. The causes are often complex and include genetics, hormones, lifestyle and environment. Treatment is individual and may include lifestyle changes, medication and in some cases surgery. A medical evaluation is the first step towards the right support and treatment.
Obesity is a chronic and complex disease that affects the body's metabolism, hormone balance and organ function. It is not just about weight, but about a medically treatable diagnosis that increases the risk of a number of serious sequelae over time.
What is obesity?
Obesity is defined as a pathological accumulation of body fat that increases the risk of ill health and impaired quality of life. It is a condition that affects both the body and the psyche - and which often requires long-term, structured treatment. The World Health Organization (WHO) classifies obesity as a chronic disease, and in Sweden it is described in national care programs as a condition with complex causes and serious consequences.
The difference between overweight and obesity
The most commonly used method for diagnosing obesity is Body Mass Index (BMI) – a measure of body weight in relation to height:
- Overweight: BMI 25–29.9
- Obesity: BMI ≥ 30
- Severe obesity (class III): BMI ≥ 40
But BMI is not the whole truth. In clinical practice, the following are also taken into account:
- Waist circumference (abdominal obesity is particularly risky)
- Body composition (e.g. via bioimpedance or DEXA)
- Metabolic risk factors (blood fats, blood sugar, liver values)
A person can therefore have a "normal" BMI but still suffer from metabolic obesity, where fat distribution or other health values indicate disease.
Symptoms and sequelae of obesity
Many symptoms linked to obesity are not directly related to weight per se, but to the metabolic and hormonal effects.
Obesity and symptoms
- Increased fatigue and lack of energy
- Sleep apnea and snoring
- Joint and back pain
- Mood swings and low self-esteem
- Increased sweating and shortness of breath
Common complications of obesity
- Type 2 diabetes
- High blood pressure
- Cardiovascular diseases
- Fatty liver (NAFLD)
- PCOS and infertility
- Certain cancers (e.g. uterine cancer, colorectal cancer)
- Depression and anxiety
High weight increases the risk of other diseases
Obesity increases the risk of a large number of diseases, especially if the weight is significantly increased or if the body fat is unevenly distributed. The higher the BMI and abdominal circumference, the greater the risk of developing secondary diseases that affect both the body and the brain.
Belly fat is more dangerous than subcutaneous fat
Body fat can be stored in different ways. Subcutaneous fat is located just under the skin – for example on the thighs and hips – and is often less dangerous. However, belly fat, which is stored inside the abdomen around the internal organs (visceral fat), is more metabolically active and linked to several serious diseases.
An increased waist circumference is often a sign of increased abdominal fat, and it is this type of fat that is most strongly linked to cardiovascular disease, type 2 diabetes and fatty liver.
Obesity affects the body's internal balance
When the body's fat stores increase, the regulation of blood pressure, blood sugar and blood lipids is often disrupted. Obesity therefore leads to an increased risk of several chronic diseases:
- High blood pressure (hypertension)
- Type 2 diabetes
- High blood fats (dyslipidemia)
- Atherosclerosis
- Heart attack and stroke
- Fatty liver disease (NAFLD)
- Gallstones
- Asthma and impaired lung function
- Sleep apnea and snoring problems
- Wear-related injuries in the hip, back and knees
- Complications during pregnancy
- Infertility (involuntary childlessness)
- Dementia
Obesity and cancer
Research shows that obesity also increases the risk of several different cancers. Examples include:
- Cancer of the uterus, ovaries and breasts
- Prostate cancer
- Cancer of the esophagus and colon
- Kidney cancer
- Cancer of the gallbladder, liver and pancreas
The exact cause is not fully understood, but there are links between fat tissue's hormone production, inflammation and cell growth that are believed to play a role.
Causes of obesity - more than calories in and out
Obesity is rarely a consequence of lifestyle alone. It is a multifactorial disease that can be due to:
- Genetic factors - heredity plays a major role in how the body stores fat
- Hormonal disorders - e.g. leptin resistance, insulin resistance, hypothyroidism
- Psychological causes – trauma, stress, emotional eating
- Medications – certain antidepressants, cortisone, insulin, etc.
- Environmental and social factors – access to food, physical activity, social conditions
How is obesity diagnosed?
Investigation of obesity includes more than just weight measurement. A careful history, physical examination and laboratory analysis are important. A health check for weight problems may include the following:
Blood tests:
- Blood sugar (glucose, HbA1c)
- Blood fats (cholesterol, triglycerides)
- Thyroid values (TSH, T4)
- Liver values (ALT, AST)
- Insulin and C-peptide
- Inflammatory markers (hs-CRP)
Body measurements:
- Weight, height, BMI
- Waist circumference
- Body composition (if necessary)
Treatment of obesity
Treatment should be individualized and aimed at both weight loss and reduced disease risk. In Sweden, healthcare is often based on stepped treatment:
1. Lifestyle change:
- Dietary advice (calorie balance, nutrient density)
- Physical activity adapted to ability
- Sleep, stress management and behavioral change
2. Behavioral support:
- Cognitive behavioral therapy (CBT)
- Digital support program or group therapy
3. Drug treatment:
- GLP-1 analogs (e.g. semaglutide)
- Other approved drugs for obesity
4. Surgical treatment:
- Gastric bypass, sleeve gastrectomy, etc.
- For patients with BMI > 35 + comorbidity, or BMI > 40
When should you seek help?
You should seek professional help if:
- You have a BMI ≥ 30
- You have weight-related complications
- You are unable to lose weight despite lifestyle changes
- You experience physical or mental problems related to your weight
Important! Obesity is a medically defined disease, not a moral failure. Through investigation and individual treatment, both quality of life and future health risks can be significantly improved. If you suspect that you are obese or if your weight is affecting your health – take the first step today. Help is available.
