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The Health Risks of Obesity

Obesity is a health hazard. It is known to increase the risk of chronic diseases such as heart disease, stroke, diabetes, liver disease and cancer, among others. These obesity-related diseases can affect quality of life very significantly and increase the risk of premature death. However, the good news is that losing weight using a health-orientated weight-management programme does bring these risks down.

What diseases are related to obesity?

As you can see, obesity affects all body systems, from the central nervous system to the joints of your feet. The issue is not to treat any of these diseases as they arise, but rather to prevent them occurring in the first place. And the best way to help that happen is to lose weight and adopt a healthy lifestyle.
When weight gain is not marked and has not been of long duration, lifestyle improvements and a healthy diet can be used to achieve a gradual reduction of the risk factors. Even if marked obesity has been present for some time, such measures will still help, but a more prompt risk reduction is desirable, and rapid and significant weight loss using a medically controlled programme should be considered, with long-term follow-up to prevent weight regain (typically the harder part of weight management).
Speak to your health professional. A full evaluation of your situation and of any relevant blood tests or other investigations is necessary to assess risk and determine the best approach in your particular case.

If you want to know more of the specific diseases associated with obesity, read on. I’ll go through the body systems, one by one.

Nervous System:

  • Stroke is more common in obesity due to high blood pressure and atherosclerosis.
  • Pseudotumor cerebri (benign intracranial hypertension) is high pressure in the fluid that surrounds the brain, causing headaches and vision problems.
  • There is strong evidence that obesity contributes to the risk of Alzheimer’s disease.

Heart and blood vessels:

  • The extra load placed on the heart having to pump blood round a much larger volume of tissue leads to high blood pressure, which is then a major cause of other diseases, such as stroke.
  • Fat accumulation around the heart makes the heart less efficient.
  • The typical changes observed in the fats, sugar and other chemicals in the blood, together with the chronic inflammation provoked by obesity predispose to atherosclerosis (thickening and hardening of the arteries). This is responsible for heart attacks, stroke and kidney disease, as well as poor blood flow to the legs (cramps or even amputations).


  • Asthma is more common in obesity.
  • Snoring and obstructive sleep apnoea syndrome. Fat accumulation around the neck narrows the airway (including at the back of the mouth) provoking snoring and even short periods of stopping breathing while asleep.


  • Altered gut hormones in obesity tend to provoke further weight gain.
  • Alteration of the gut microbiome in obesity is associated with further weight gain. The bacteria can increase chronic inflammation and also extract an additional 10% of calories from food.
  • Gastro-oesophageal reflux (heartburn) due to acid rising from the stomach into the oesophagus is more common.
  • Haemorrhoids are more common due to the excess weight impeding venous return from the pelvis and lower abdomen.

Internal organs:

  • Fatty liver disease is a problem of fat accumulation in the liver cells. It is a very important risk factor for metabolic syndrome and type 2 diabetes. It can also lead to more serious liver disease (cirrhosis, liver cancer).
  • Gallstones are more common in obesity. Treatment may require surgery.
  • Fatty infiltration of the pancreas is thought to be an important factor in the onset of type 2 diabetes.
  • Chronic kidney disease may occur not only from atherosclerosis of its blood supply but also because of direct damage to the fine structures within the kidney.
  • Heart (see above).

Reproductive organs:

  • Obesity reduces fertility in both men and women.
  • Polycystic ovary syndrome (PCOS) both predisposes to obesity and can be caused by obesity. (I shall discuss PCOS in a separate article.)

Bones and joints:

  • The increased weight load on the hips and knees will provoke pain and stiffness.
  • Decreased bone mineral density (osteopenia and osteoporosis), with increased risk of fractures.
  • Gout is more common as the uric acid concentration in the blood is increased in obesity.


  • Rashes are common in the skinfolds due to persistent moistness and difficult hygiene.
  • Acanthosis nigricans is a darkening and thickening of the skin, particularly affecting the neck and skinfolds such as the axillae, but it can also be seen in the groin and even on the forehead.

Endocrine and metabolic:

  • Metabolic syndrome is a group of signs that indicate increased risk of disease:
    – High blood pressure
    – Increased waist circumference (♂ >40 inches [102 cms] ♀ >35 inches [89 cms])
    – Altered blood fats (dyslipidaemia)
    – Fasting blood sugar >5.6 mmol/L (100 mg/dl)
  • Diabetes.
  • Alteration of the gut hormones that can increase weight gain


  • Many cancers are known to be more frequent in obesity: colon, breast, endometrium, liver, pancreas and others.
  • Surgical complications. The incidence of complications after surgery, such as wound infection or respiratory problems, is higher in obese individuals.