Health Risks from Obesity: Common Short and Long Term Complications

What can obesity actually do to your health?

The answer is more complicated than a number on the scales. Obesity can affect several parts of the body at the same time. Some effects may be noticeable in everyday life, such as breathlessness, tiredness, poor sleep, reduced mobility or joint discomfort. Other problems, including high blood pressure, abnormal blood fats and changes in blood glucose, may develop without obvious symptoms.

Over time, obesity is associated with a higher risk of conditions such as type 2 diabetes, cardiovascular disease, obstructive sleep apnoea, osteoarthritis and metabolic dysfunction associated steatotic liver disease (MASLD).

That does not mean that everyone living with obesity will develop these conditions. Health risk also depends on factors such as age, genetics, where body fat is stored, physical activity, smoking, medicines and existing health conditions.

This page explains the main health risks linked with obesity, how clinicians assess them and why weight management is only one part of looking after your health.

Key things to know

• Obesity can affect cardiovascular, metabolic, respiratory, musculoskeletal and mental health.
• Some effects can affect day to day life, while others may develop gradually without obvious symptoms.
• High blood pressure, abnormal blood fats, prediabetes and type 2 diabetes are important metabolic and cardiovascular concerns.
• Obesity is strongly associated with obstructive sleep apnoea and can also affect mobility and joint health.
• Central adiposity, or carrying more fat around the waist, is linked with higher cardiometabolic risk.
• BMI is useful for assessing weight in adults, but it does not describe a person's full health picture.
• Existing health conditions should be assessed and treated even while someone is working on weight management.

What Can Obesity Cause?

There is no single list of diseases that obesity directly causes in every person.

Instead, obesity can change processes in the body that influence blood pressure, blood glucose, blood fats, breathing, joint loading and how fat is stored. These changes can increase the likelihood of several health conditions.

NICE identifies weight related conditions including:

• high blood pressure
• abnormal blood fats
• obstructive sleep apnoea
• cardiovascular disease
• prediabetes
• type 2 diabetes
• respiratory and musculoskeletal problems
• metabolic liver disease.

The level of risk varies from person to person. Someone can live with obesity without developing every condition on this list, while another person may have several health problems at the same time.

What Are the Short Term Effects of Obesity?

Not every effect of obesity starts as a formal medical diagnosis.

Some people first notice changes in how they feel or move. These can include:

• breathlessness during activity
• reduced stamina
• difficulty moving comfortably
• joint or back discomfort
• snoring
• poor quality sleep
• persistent tiredness.

These symptoms can have many causes, so they should not automatically be blamed on weight. For example, ongoing breathlessness could be linked to a heart or lung condition, while tiredness may be related to poor sleep, anaemia, medication or another health problem.

If a symptom is persistent or getting worse, it is worth having it assessed rather than assuming it is simply because of obesity.

How Can Obesity Affect Mobility and Joints?

Carrying more body weight can make movement more physically demanding. Walking, climbing stairs, standing for long periods or getting up from a chair may become harder for some people.

Obesity is also associated with osteoarthritis, particularly in weight bearing joints such as the knees and hips. Greater mechanical loading is one reason for this link, although other biological factors may also play a role.

Joint pain can then make movement more difficult, which may reduce physical activity. This can become frustrating when someone is trying to manage their weight.

That is why support should take pain and mobility into account rather than simply advising someone to exercise more. A GP, physiotherapist or other healthcare professional can help identify activities that are suitable for the person's current ability.

How Does Obesity Affect Sleep?

Sleep is an important part of health, but it is easy to overlook when discussing obesity.

Obesity is strongly associated with obstructive sleep apnoea. This happens when the airway becomes narrowed or blocked during sleep, causing breathing to stop and start repeatedly.

Possible signs include:

• loud or persistent snoring
• waking repeatedly during the night
• morning headaches
• unrefreshing sleep
• excessive daytime tiredness
• difficulty concentrating.

Not everyone who snores has sleep apnoea. However, persistent symptoms are worth discussing with a GP because untreated sleep apnoea can affect blood pressure, concentration and cardiovascular health.

Sleep apnoea should also be treated in its own right. It does not need to be left untreated while someone works on their weight.

Can Obesity Raise Blood Pressure?

Yes. High blood pressure, or hypertension, is one of the established health conditions associated with obesity.

The important thing about hypertension is that it often causes no obvious symptoms. Someone can feel completely well while their blood pressure remains higher than recommended.

Over time, persistent high blood pressure can increase the risk of cardiovascular problems, including heart disease and stroke.

This is why blood pressure checks are an important part of a wider health assessment. If hypertension is identified, it should be managed rather than waiting for weight loss first.

Can Obesity Affect Cholesterol and Other Blood Fats?

It can. Obesity is associated with dyslipidaemia, which means having abnormal levels of fats in the blood.

This can involve changes in LDL cholesterol, HDL cholesterol or triglycerides. The overall pattern matters because abnormal blood fats can contribute to cardiovascular risk, particularly when they occur alongside high blood pressure, type 2 diabetes or central adiposity.

A blood test can help identify these changes. There is no reliable way to tell whether your cholesterol is high simply from how you feel.

How Does Obesity Affect Heart Health?

Obesity can increase cardiovascular risk through several connected factors.

These may include:

• high blood pressure
• abnormal blood fats
• insulin resistance
• type 2 diabetes
• central adiposity
• reduced physical fitness.

NICE recognises cardiovascular disease as an important obesity related condition. Higher waist to height ratios are also associated with increased cardiovascular risk.

This does not mean obesity is the only factor involved. Smoking, age, family history, blood pressure, cholesterol and other health conditions also affect cardiovascular risk.

Can Obesity Increase Stroke Risk?

Obesity is associated with a higher risk of stroke, partly through conditions such as high blood pressure, type 2 diabetes and cardiovascular disease.

This is one reason it is useful to look beyond weight alone. Managing blood pressure, blood glucose and blood fats can be important alongside weight management.

If you have concerns about your cardiovascular risk, a GP can assess the factors that apply to you rather than relying on BMI alone.

Why Is Obesity Linked With Type 2 Diabetes?

Type 2 diabetes is one of the main long term conditions associated with obesity.

Excess body fat, particularly around the abdomen, can contribute to insulin resistance. This means the body does not respond to insulin as effectively as it normally would. Over time, blood glucose can rise and may eventually reach the level used to diagnose type 2 diabetes.

Central adiposity is important here. NICE notes that a higher waist to height ratio is associated with increased risk of type 2 diabetes, hypertension and cardiovascular disease.

However, having obesity does not mean that someone will definitely develop diabetes. Family history, ethnicity, age, activity and other factors also affect risk.

What Is Central Adiposity and Why Does It Matter?

Central adiposity means carrying more fat around the middle of the body.

BMI tells you how your weight compares with your height, but it does not show where fat is stored. This is why waist to height ratio can provide additional information in adults with a BMI below 35 kg/m².

NICE classifies waist to height ratios as:

• 0.4 to 0.49: healthy central adiposity
• 0.5 to 0.59: increased central adiposity
• 0.6 or above: high central adiposity.

Higher levels of central adiposity are associated with increased risk of type 2 diabetes, hypertension and cardiovascular disease. NICE advises adults to try to keep their waist circumference below half their height.

These measurements are useful for understanding risk, but they are not a diagnosis on their own.

Can Obesity Affect the Liver?

Yes. Excess weight is strongly associated with metabolic dysfunction associated steatotic liver disease, commonly known as MASLD. The condition involves fat building up in the liver and is often linked with overweight, obesity and other metabolic risk factors.

MASLD often causes no obvious symptoms, so someone may not know they have it. It may be discovered through blood tests, imaging or investigations carried out for another reason.

The risk can be higher when fatty liver occurs alongside conditions such as type 2 diabetes or abnormal blood fats.

This is another example of why feeling well does not always mean that there are no weight related health risks.

Can Obesity Affect Breathing?

It can. Some people living with obesity experience reduced exercise tolerance or breathlessness, while obesity is also strongly associated with sleep related breathing problems such as obstructive sleep apnoea.

In more severe cases, obesity can contribute to obesity hypoventilation syndrome, where breathing does not remove enough carbon dioxide from the body.

However, breathlessness should never automatically be attributed to weight. Heart disease, lung disease, anaemia and other conditions can cause similar symptoms and may need treatment.

Can Obesity Affect Mental Wellbeing?

The relationship between obesity and mental wellbeing is complex.

Living with obesity can affect daily activities, mobility, sleep and confidence. Some people may also experience weight stigma, discrimination or negative comments about their body. These experiences can affect emotional wellbeing and may make people less comfortable seeking healthcare.

Mental health can also affect weight and eating patterns, which is why NICE recommends considering factors such as depression, anxiety, self esteem and experiences of weight stigma when supporting people with obesity.

Mental health should be treated as part of overall health, not as an afterthought.

Does a Higher BMI Always Mean Worse Health?

No. BMI is useful for identifying overweight and obesity in adults, but it does not give a complete picture of someone's health.

For example, BMI does not show where body fat is stored and may be less accurate in people with high muscle mass. NICE therefore recommends considering factors such as central adiposity, existing health conditions, family history, ethnicity, medicines and other individual circumstances.

This is why two people with the same BMI can have different health risks.

Do Obesity Risks Differ by Ethnic Background?

Yes. Cardiometabolic risk can occur at a lower BMI in some ethnic groups.

NICE recommends lower BMI thresholds for assessing health risks in people from South Asian, Chinese, other Asian, Middle Eastern, Black African and African Caribbean backgrounds.

This is important because using one BMI threshold for everyone may not give a complete picture of risk.

Can Obesity Affect Quality of Life?

Yes. Health risks are not only about future diagnoses.

Someone may notice that everyday activities take more effort, sleep is less refreshing, joints hurt or certain activities have become harder. These changes can affect work, social activities, exercise and general wellbeing.

That means weight management should not be viewed only through the number on the scales. Improving mobility, sleep, fitness and day to day comfort can also be meaningful health goals.

Can Losing Weight Reduce Health Risks?

It can. Losing weight can reduce the risk of several obesity related health problems, although the amount of benefit varies between people and conditions.

UK public health guidance states that health benefits can be achieved from losing at least 5% of current body weight.

The NHS also notes that losing 5% to 10% of body weight can improve health.

Importantly, this does not mean someone needs to reach a particular “perfect” weight before their health can improve. Changes in diet and physical activity can also support health even when weight loss is modest.

Should Health Conditions Wait Until Weight Has Come Down?

No.

A person does not need to lose weight before receiving treatment for high blood pressure, diabetes, sleep apnoea, abnormal blood fats or other health conditions.

NICE recommends managing weight related comorbidities when they are identified rather than waiting for weight reduction first.

In practice, this means several parts of care can happen at the same time. Someone may work on weight management while also taking prescribed blood pressure medication, having diabetes monitored or receiving treatment for sleep apnoea.

What Health Checks May Be Relevant?

The checks someone needs depend on their symptoms, BMI, medical history and existing conditions.

A healthcare professional may consider:

• BMI and waist measurement where appropriate
• blood pressure
• blood glucose or HbA1c
• cholesterol and other blood fats
• liver related tests
• sleep symptoms
• joint and mobility problems
• mental wellbeing.

Not everyone needs every test. A GP or other healthcare professional can decide which checks are appropriate based on the person's individual risk.

When Should Someone Seek Medical Advice?

Consider speaking to a GP if you are living with obesity and have concerns about:

• persistent or unexplained breathlessness
• loud snoring or excessive daytime sleepiness
• high blood pressure
• abnormal blood glucose
• persistent tiredness
• ongoing joint or mobility problems
• symptoms that are affecting everyday life.

It is also worth asking for support if your weight is increasing and you are finding it difficult to manage on your own.

Getting help does not mean you need to have reached a certain weight or developed a serious complication. A healthcare professional can help you understand your current health risks and discuss suitable next steps.

Can Prescription Weight Management Treatment Help?

Prescription weight management medicines may be suitable for some adults who meet specific clinical criteria.

Current NICE guidance includes medicines such as tirzepatide, semaglutide, liraglutide and orlistat in particular circumstances. Eligibility, treatment length and prescribing requirements differ between medicines and patient groups.

These medicines are generally considered as part of a wider weight management plan rather than as a standalone solution. Existing conditions such as high blood pressure, diabetes or sleep apnoea still need appropriate care.

Why Is Long Term Management Important?

Weight can change over time, and regaining some weight after weight loss is common. That does not mean that previous efforts were wasted or that someone has failed.

Long term weight management may involve a combination of nutrition, physical activity, behavioural support, medical monitoring and medication where appropriate.

The aim is not simply to reach a number and stop. It is to support health in a way that can fit into everyday life.

Health Risks of Obesity: Key Takeaway

Obesity can affect more than body weight. It is associated with health risks involving the heart, blood pressure, blood glucose, sleep, joints, liver and mental wellbeing.

Some effects may be noticeable, such as breathlessness, reduced mobility, tiredness or joint discomfort. Others, including high blood pressure, abnormal blood fats and changes in blood glucose, can develop without obvious symptoms.

The important point is that these risks are not guaranteed. Obesity is one part of a much wider picture that includes age, genetics, ethnicity, smoking, activity, medicines, existing health conditions and where body fat is stored.

If you are living with obesity, you do not need to wait for a serious complication before asking for support. A healthcare professional can assess your individual risk, check for related conditions and discuss weight management alongside any treatment you may need.

Medical Disclaimer

This article provides general information about obesity and associated health risks in adults. It is not a diagnosis or a substitute for medical advice. Symptoms such as breathlessness, fatigue, pain or sleep problems can have many possible causes and should not automatically be attributed to body weight. Speak to a qualified healthcare professional if you have concerns about your weight, symptoms or overall health.