What are weight-related diseases and an increased risk of poor health?
Weight-related diseases are medical conditions that develop, worsen or become more common in connection with overweight and obesity. In particular, an increased amount of visceral fat, meaning fat stored around the internal organs, is linked to an increased risk of several diseases.
Obesity is now recognised as a chronic and complex disease that affects many of the body's organs and functions. Its development is influenced by an interaction between biological, genetic, psychological, social and environmental factors.
The health consequences that can arise include metabolic diseases, cardiovascular disease, hormonal disorders, sleep disorders and load-related problems affecting the joints and musculoskeletal system. The risk of related conditions generally increases with the degree of overweight, but the distribution of fat in the body is also very important.
The biological effects of overweight and obesity
Obesity affects the body's biology in several ways and is linked to changes in metabolism, hormonal regulation and inflammatory processes. Adipose tissue functions not only as an energy store but also as an active organ that releases hormones and signalling substances that affect many of the body's functions.
As the amount of body fat increases, particularly around the internal organs, the low-grade inflammation often seen in obesity also increases. This can contribute to reduced insulin sensitivity and an increased risk of diseases such as type 2 diabetes, cardiovascular disease and fatty liver disease.
Obesity also affects the biological systems that regulate hunger, fullness and energy balance. During weight loss, the body's compensatory mechanisms are activated, which can lead to increased hunger, changes in the levels of hormones that regulate appetite and a reduction in energy expenditure. These adaptations are an important explanation for why many people find it difficult to maintain weight loss over time.
How weight loss reduces the risk of serious related diseases
A weight loss of just 5 to 10 per cent of body weight can provide significant health benefits. Research shows that even moderate weight loss can improve blood sugar control, blood pressure and blood lipids, as well as reduce the risk of several weight-related diseases.
As fat mass decreases, the body's energy metabolism improves and the low-grade inflammation often associated with obesity can decrease. This can contribute to improved insulin sensitivity and reduced strain on the cardiovascular system. Greater weight loss is generally associated with even greater health benefits, but even relatively small changes in body weight can be important for long-term health.
Myth vs fact about weight loss and health
Myth: You need to reach a body mass index (BMI) below 25 to gain health benefits from weight loss.
Fact: The health benefits of weight loss often begin long before BMI reaches the healthy range. A weight loss of just 5 to 10 per cent of body weight can improve blood sugar, blood pressure, blood lipids and other risk factors for disease. Even if you still have overweight or obesity after losing weight, your metabolic health may have improved significantly.
Myth: Overweight mainly affects appearance and physical mobility.
Fact: Obesity affects the whole body and is linked to an increased risk of type 2 diabetes, cardiovascular disease, fatty liver disease, sleep apnoea and osteoarthritis, among other conditions. The greatest health consequences often involve the body's internal organs, metabolism and hormonal systems. Weight loss can improve metabolic health, physical function and quality of life, as well as reduce symptoms such as pain, tiredness and shortness of breath.
Metabolic syndrome: Type 2 diabetes, high blood pressure and blood lipid disorders
Obesity is strongly linked to the development of metabolic syndrome, a collective term for several risk factors that often occur together, including insulin resistance, high blood pressure, elevated blood lipids and an increased amount of abdominal fat. These factors increase the risk of both type 2 diabetes and cardiovascular disease.
Insulin resistance means that the body's cells respond less effectively to insulin, making it more difficult to regulate blood sugar levels. To compensate, the body produces more insulin, but over time this ability can decrease, increasing the risk of prediabetes and type 2 diabetes. At the same time, obesity is associated with changes in blood pressure and blood lipids that can further affect metabolic health.
Research shows that weight loss can improve insulin sensitivity, lower blood pressure and have beneficial effects on blood lipids. A moderate weight loss of just 5 to 10 per cent of body weight can lead to significant improvements in several of the risk factors included in metabolic syndrome.
Cardiovascular disease and stroke
Obesity is linked to an increased risk of cardiovascular disease and stroke through several interacting mechanisms. Changes in blood lipids, blood pressure, blood sugar and inflammatory processes can together contribute to the development of atherosclerosis, which increases the risk of heart attack and stroke.
An increased amount of body fat, particularly around the abdomen, is often associated with elevated levels of triglycerides, lower levels of HDL cholesterol and other changes that can affect blood vessel health. At the same time, high blood pressure is more common in obesity, which places additional strain on the heart and blood vessels over time.
Research shows that weight loss can improve several of the risk factors that contribute to cardiovascular disease. For people living with obesity, lifestyle changes and, when medically indicated, medication can contribute to improved metabolic health and a reduced risk of future cardiovascular events.
Fatty liver disease (MASLD/MASH) and the effects of overweight on the liver
Overweight and obesity are strongly linked to fatty liver disease, now known as MASLD (metabolic dysfunction-associated steatotic liver disease). The condition involves fat accumulating in the liver, which can affect liver function and metabolism. In some people, a more advanced form involving inflammation and liver damage develops, known as MASH (metabolic dysfunction-associated steatohepatitis).
Fatty liver disease often causes no clear symptoms in its early stages, but if the disease progresses, it can lead to scarring of the liver (fibrosis) and, in some cases, cirrhosis.
Weight loss is one of the most effective treatments for fatty liver disease. Even moderate weight loss can reduce the amount of fat in the liver, while greater weight loss can help improve inflammation and slow disease progression.
Osteoarthritis, joint pain and reduced mobility
Overweight and obesity are associated with an increased risk of osteoarthritis, particularly in weight-bearing joints such as the knees and hips. A higher body weight means increased strain on the joints during everyday movements, which over time can contribute to pain, reduced function and the development of osteoarthritis.
At the same time, obesity does not affect the joints only through increased mechanical strain. Adipose tissue also releases signalling substances that can contribute to inflammatory processes in the body and affect joint health. Osteoarthritis is therefore now regarded as a condition in which both biomechanical and biological factors play an important role.
Research shows that weight loss can reduce strain on the joints, relieve pain and improve physical function. In combination with regular physical activity and adapted exercise, this can contribute to increased mobility and improved quality of life.
Breathing pauses and sleep apnoea in overweight
Obstructive sleep apnoea is common in overweight and obesity. The condition means that the upper airways repeatedly collapse during sleep, leading to pauses in breathing, drops in oxygen levels and disrupted sleep quality. Sleep apnoea is associated with an increased risk of high blood pressure, cardiovascular disease and poorer metabolic health, among other conditions.
Sleep apnoea and lack of sleep can also affect the body's regulation of hunger, fullness and energy balance, which can make it more difficult to maintain healthy lifestyle habits. Weight loss can reduce the symptoms of sleep apnoea and, in some cases, lead to significant improvements in the condition.
How do overweight and obesity affect PCOS and fertility?
Overweight and obesity can worsen the hormonal and metabolic changes that often occur with polycystic ovary syndrome (PCOS). Many women with PCOS have insulin resistance, which can contribute to increased levels of androgens (male sex hormones) and affect ovulation.
When ovulation becomes irregular or does not occur, fertility can be affected and it can become more difficult to get pregnant. Overweight can also worsen insulin resistance and thereby contribute to worsening PCOS symptoms.
Research shows that weight loss can improve insulin sensitivity, contribute to more regular menstrual cycles and increase the likelihood of ovulation in women with PCOS. Even moderate weight loss can provide significant improvements in both metabolic health and reproductive function.
Medical treatment, diet and physical activity in combination
For many people living with overweight or obesity, biological mechanisms that affect hunger, fullness and energy balance can make it difficult to achieve and maintain weight loss through lifestyle changes alone. In these cases, medication can be a valuable complement to diet, physical activity and other healthy lifestyle habits.
Modern medicines for obesity, such as semaglutide (Wegovy), liraglutide (Saxenda) and tirzepatide (Mounjaro), affect the body's systems for appetite regulation and energy balance. Treatment can contribute to increased fullness, reduced appetite and lower energy intake over time. Many patients also experience fewer thoughts about food and reduced cravings between meals during treatment.
Medication does not replace healthy lifestyle habits, but for some people it can create better conditions for making and maintaining changes in diet and physical activity, sleep and recovery. When treatment is combined with long-term support and sustainable habits, it can contribute to weight loss, weight stability and improved metabolic health.
When should you seek help for weight-related problems that increase the risk of disease?
It can be valuable to seek medical advice if you have obesity (body mass index (BMI) ≥30) or overweight (BMI ≥27) in combination with weight-related health problems such as type 2 diabetes, high blood pressure, sleep apnoea or other metabolic risk factors. Obesity is a chronic disease that often requires more than temporary lifestyle changes to achieve and maintain lasting improvement.
It may also be appropriate to seek support if you feel that your weight is affecting your health, quality of life or physical function, or if previous attempts at weight loss have not produced the desired result. A medical assessment can help identify risk factors, detect any related diseases and develop a treatment plan adapted to your individual needs.
Frequently asked questions about weight-related diseases (FAQ)
Which diseases does obesity increase the risk of?
Obesity is linked to an increased risk of several diseases and health conditions. Some of the most common are type 2 diabetes, high blood pressure, cardiovascular disease, fatty liver disease (MASLD/MASH), obstructive sleep apnoea and osteoarthritis. Obesity is also associated with an increased risk of infertility and hormonal disorders in PCOS, as well as certain types of cancer.
The risk of related diseases is influenced not only by body weight itself, but also by factors such as the distribution of fat in the body, genetic factors, age and the presence of other risk factors.
How much weight do I need to lose to reduce health risks?
A weight loss of just 5 to 10 per cent of body weight can provide significant health benefits. Research shows that even moderate weight loss can improve blood sugar, blood pressure, blood lipids and other risk factors for disease. Greater weight loss is generally associated with even greater health benefits, but even relatively small changes in body weight can make a difference.
Why do my knees hurt more when I have overweight?
Overweight and obesity are associated with increased strain on weight-bearing joints such as the knees and hips. As body weight increases, the joints are exposed to greater forces during everyday activities such as walking, standing and climbing stairs, which can contribute to pain and reduced function.
At the same time, obesity does not affect the joints only through increased mechanical strain. Adipose tissue also releases signalling substances that can contribute to inflammatory processes in the body and affect joint health.
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