Complications and Health Risks of Obesity

Heather Campbell
 min read

The complications and health risks of obesity are more intricate than you may think.

Complications and Health Risks of ObesityAccording to Frank Hu, professor of Nutritional Medicine and epidemiologist at the Harvard School of Public Health, obesity is not just one-size-fits-all.

As a general rule, obesity involves long-term inflammation in the fat cells caused within the body itself. Obesity causes complications like fatty liver, joint wear or osteoarthritis, asthma, heart disease, diabetes, autoimmune diseases, high blood pressure, psychological problems, and skin issues.

However, not everyone who is overweight has a greater risk of disease, which is called the obesity paradox.

Actually, this is not so paradoxical if we think about it for a moment. Fat is useful because it protects us and acts as a buffer, even if we become chronically ill.

People with a layer of fat therefore have more reserves than people with just skin and bones.

Continue reading to learn about the three types of obesity complications, including an extensive list of possible complications due to obesity and a high BMI.

Complications and health risks of obesity: Introduction

Does more weight lead to more disease?

About 20% of overweight people is metabolically healthy. This means that there is not that much going on in their blood.

By the way, you can also infer metabolic health from the following:

  • A physically fit person
  • Normal cholesterol levels
  • Normal sensitivity to insulin
  • Normal blood pressure
  • A normal blood sugar
  • A healthy belly size
  • Good waist-to-hip ratio

With an increasingly higher BMI, we can say that health risks are increasing for all populations.

For example, people with a BMI of 45 usually have a life span of 20 years younger than their fitter counterparts.

The risk of disease is much higher with an elevated BMI. At least, if the definition of disease is that it makes you either die sooner or have to sacrifice quality of life.

Three types of complications and diseases resulting from obesity

The complications and diseases that occur with too much overweight can be divided into three categories:

Production of inflammatory cells by fat cells

First, complications exist due to inflammatory substances produced by the fat in our bodies.

This is called the metabolic effect of fat cells, leading to high blood pressure, diabetes, bile duct disease, and cardiovascular disease.

Our adipose tissue is not just a pile of passive fat cells but a kind of storage cabinet for active fat cells.

In reality, a fat cell is an active cell that produces all kinds of hormones and inflammatory cells.

The thyroid makes the thyroid hormone, and the pancreas makes insulin. All organs that make hormones are called endocrine organs. Our adipose tissue produces hormones and is therefore also an endocrine organ.

Obesity involves long-term inflammation in the fat cells, which is different from acute inflammation that you get from an injury, for example.

Inflammatory cells (pro-inflammatory cytokines) are found in fat cells.

And when too much fat is stored, the fat cells become distressed. They become stressed, so to speak. Stress is usually an injury, and what will the body cells do? They send their immune cells after it.

Subsequently, therefore, the whole thing will inflame. So we are not talking about inflammation caused by bacteria or a wound from the outside, but rather an inflammation from the inside.

The result of a so-called excessive immune response in the cells. This inflammation is harmful to your health, causes irritation in the blood vessels, and contributes to arteriosclerosis.

Also, the fat cell can no longer properly absorb the excess calories because of stress and inflammation. You would think that this is not a big deal (because then the fat cell cannot grow even larger), but it is actually problematic.

Because this is where things really go wrong. New fat cells then simply form in places where they don’t belong, such as around the intestines, in and around the heart, in the muscles, and even in the kidneys and pancreas.

Good to know: In professional jargon, this is called ectopic fat.

Microbiome in the gut out of balance

Second, complications exist due to changes in the microbiome in the intestines (gut bacteria).

Our gut bacteria have a significant impact on our metabolism and defenses.

Research has shown that this affects the amount and location of fat deposited in our bodies, and our microbiome also affects insulin resistance.

Obesity involves a microbiome that is out of balance. But is this the cause or rather the consequence of being overweight?

Poop transplants in overweight people lead to an improvement in the microbiome’s diversity and an improvement in insulin sensitivity.

Consequences of fat gain in the body

Third, complications exist due to the increase in the amount and accumulation of fat.

Examples of such complications are sleep apnea and osteoarthritis.

Possible complications of obesity

Fatty liver

Fatty liver disease (non-alcoholic fatty liver disease) is currently the leading cause of liver disease worldwide.

It is now estimated that about 25 to 30% of adults in the (Western) world have it.

Non-alcoholic fatty liver progresses to liver inflammation (non-alcoholic hepatic steatosis) in about 33% of people.

And after such liver inflammation, you can get liver fibrosis or even liver cancer.

Fatty liver also occurs in people with more visceral or ectopic fat. So there are also people with a normal weight who nevertheless suffer from fatty liver (the so-called thin on the outside, fat on the inside people).

This is thought to occur in about 10 to 15% of people of normal weight.

Abdominal circumference would provide more information than BMI in this area. After bariatric surgery, non-alcoholic liver fat can completely reverse and improve in most people.

You can think of fatty liver as a complication of type 2 diabetes or hyperinsulinemia. Elevated glucose levels give hyperinsulinemia (and type 2 diabetes). This controls the conversion of glucose to fat in the liver.

Important fact: about 70% of people with type 2 diabetes have non-alcoholic fatty liver.


Overweight people are more likely to suffer from joint wear or osteoarthritis. In practice, this often has the most significant impact on the knee.

Osteoarthritis is more common in non-load-bearing joints such as the hands.

Such osteoarthritis is thought to be caused by a chronic inflammatory response in the fat cells.

Gout is 2 to 3 times more common in overweight people.


Both asthma and childhood obesity have increased in recent times.

Obesity increases the likelihood of developing asthma. How this comes about is not yet scientifically proven.

The sheer impact of weight can be a reason for this. Still, it can also be related to a disorder of the immune system, hormones, or the long-term use of inhalers containing steroids.

Heart diseases

The NHANES (National Health and Nutrition Examination Survey) database, which collected cause-of-death information from 2.3 million Americans, has shown an association between severe obesity and cardiovascular disease.

An increased BMI also leads to an increase in cardiovascular disease risk factors, such as high blood pressure, elevated cholesterol levels, and diabetes.

By the way, some studies show that even without those risk factors, there is still an increased risk of heart disease with an increased BMI.


Most patients with diabetes are overweight. Hence, obesity is often seen as the cause of diabetes. This is the case in about 80% of people with type 2 diabetes.

So this also means that about 20% of people with type 2 diabetes are not obese.

Usually, type 2 diabetes and obesity have a common denominator: insulin resistance.

When fat cells become overfilled by 1 giant fat droplet, they cannot function properly. An inflammatory response then develops, which can contribute to the development of insulin resistance.

Healthy fat cells with lots of tiny fat droplets, on the other hand, are not insulin resistant, and then you are much less likely to get diabetes.

Several scientific studies conclude that in a group of overweight or severely overweight people, the risk of diabetes increases significantly.

That does not mean that one causes the other.

High blood pressure

Children who are severely overweight are up to 3 times more likely to have a high blood pressure than children of average weight.

Even in adults, blood pressure improves after losing weight and some excess pounds.

Autoimmune diseases

There may be a strong link between obesity and various autoimmune diseases such as psoriasis, rheumatism, and multiple sclerosis.

However, this is not yet 100% certain, and should there be a link, it does not mean that it is a causal link.

Heart failure

Overweight and obesity are related to an increased risk of heart failure.

There are scientific studies that show that once people have experienced heart failure, they are better off being overweight.

This is where the obesity paradox comes in again.

It is likely that if you are already suffering from severe obesity as a child, it is quite a drain on your heart from a young age. As a result, you are more likely to have heart failure.

But once you have experienced heart failure, it is debilitating to your health. People taper off completely.

Then, if you are a little overweight, you have a little more reserves to pull you through in practice.

Skin defects

Skin problems such as stretch marks (places where the skin breaks) and cellulite are seen more often in obese people, due to the pressure on the skin from the growing fatty tissue.

Some areas of the skin develop a dark discoloration (this is called acanthosis nigricans).

You can see this at the neck and knuckles, for example.


People who are severely overweight are about 2 times more likely to suffer a stroke or cerebral hemorrhage.


Obesity accounts for about 20% of all cancers.

Obesity is also cited as a cause of about one-third of breast cancers, colon cancers, kidney cancers, endometrial cancers, and esophageal cancers.

If you are pretty overweight, this is definitely not a good starting point for getting cancer. In fact, being overweight actually makes you more likely to metastasize.

Being overweight also makes it much harder to properly dose chemotherapy and radiotherapy.

Infectious diseases

There is a disorder of the immune system in obese people.

This makes overweight people more susceptible to developing various inflammations such as inflammation after surgical wounds, skin inflammation, cystitis, and autoimmune disorders.

Related: To learn more about infectious diseases and how they’ve become overshadowed by chronic diseases, read our other article Going from Infectious Diseases to Chronic Diseases: An Evolutionary Perspective

Psychological problems

Overweight people face an incredible amount of prejudice and condemnation (for example, in the workplace and even at consultations with certain doctors).

Depression is, therefore, more common in obese people (fat-phobia and fat shaming can cause considerable mental problems).

Unfortunately, there is still a stigma on our plus-size fellow men and women.

And women are even more affected by this than men.

This is probably due to an excess of social pressure to conform to specific ideal images and to present yourself in the best possible way.

Fortunately, we are now seeing more curvy supermodels in the media.

Cholesterol and fats

Heavy obesity can be associated with elevated levels of bad LDL cholesterol, increased triglycerides, and decreased levels of good HDL cholesterol.

Sleep apnea

Sleep apnea is a condition often seen in overweight people (which means that losing weight improves sleep quality for overweight people).

Sleep quality is disrupted, and one often has long pauses between breaths at night due to the throat being squeezed shut by too much neck fat.

There is also less lung volume available due to more pressure from the abdomen on the diaphragm.

Sleep apnea, again, is associated with a whole list of other diseases such as high blood pressure, liver function disorders, insulin resistance, elevated cholesterol which might kill you, and diabetes.

So sleeping well really does matter for your long-term health! Complications and health risks of obesity also include sleeping.

Other consequences of an increased BMI

Furthermore, with an elevated BMI, there is also a risk of:

  • More complications in surgery and anesthesia
  • Pancreatitis
  • Reduced fertility in women
  • Kidney stones
  • Polycystic Ovarian Syndrome (PCOS)
  • Decreased sperm quality
  • Reflux diseases
  • Renal failure
  • Less success in fertility treatments
  • Gallstones

Complications and health risks of obesity: Conclusion

The number of complications and health risks of obesity are innumerable.

Although medicine has improved greatly, this is no excuse to allow oneself to become obese if you can avoid it.

Being obese also means being less likely to be physically active, with additional health risks resulting from such a sedentary lifestyle and too frequent use of a mobility scooter for heavy persons among other things!

Tip: Check our other article for practical tips to eat more healthily: What Are Healthy Eating Guidelines? Tips and Eating Rules from a Nutritionist

About Heather Campbell

As a nutritionist, my field of specialization is science-based nutritional advice but more importantly, it is my goal to share capturing and inspiring stories, examples and solutions which can help plus-size individuals overcome their specific difficulties. Read More