Whether or not obesity should be considered a disease on its own, it is also an important risk factor for many chronic physical and mental illnesses. The generally accepted view is that being overweight causes similar health problems to obesity, but to a lesser degree.
- 1 Cardiological
- 2 Dermatological
- 3 Endocrine
- 4 Reproductive system
- 5 Gastrointestinal
- 6 Neurological
- 7 Oncological
- 8 Psychiatric
- 9 Respirological
- 10 Rheumatological and orthopedic
- 11 Urological and nephrological
- 12 References
Ischemic heart disease
Obesity is associated with cardiovascular diseases including angina and myocardial infarction. A 2002 report concluded that 21% of ischemic heart disease is due to obesity while a 2008 European consensus puts the number at 35%.
Congestive heart failure
High blood pressure
More than 85% of those with hypertension have a BMI greater than 25. The risk of hypertension is 5 times higher in the obese as compared to those of normal weight. A definitive link between obesity and hypertension has been found using animal and clinical studies, which have suggested that there are multiple potential mechanisms for obesity-induced hypertension. These mechanisms include the activation of the sympathetic nervous system as well as the activation of the renin–angiotensin-aldosterone system.
Abnormal cholesterol levels
Deep vein thrombosis and pulmonary embolism
One of the strongest links between obesity and disease is that with type 2 diabetes. These two conditions are so strongly linked that researchers in the 1970s started calling it “diabesity”. Excess weight is behind 64% of cases of diabetes in men and 77% of cases in women.
Polycystic ovarian syndrome (PCOS)
Obesity leads to infertility in both men and women. This is primarily due to excess estrogen interfering with normal ovulation in women and altering spermatogenesis in men. It is believed to cause 6% of primary infertility. A review in 2013 came to the result that obesity increases the risk of oligospermia and azoospermia in men, with an of odds ratio 1.3. Being morbidly obese increases the odds ratio to 2.0.
Complications of pregnancy
Obesity is related to many complications in pregnancy including: haemorrhage, infection, increased hospital stays for the mother, and increased NICU requirements for the infant. Obese women have more than twice the rate of C-sections compared to women of normal weight. Obese women also have increased risk of preterm births and low birth weight infants.
Those who are obese during pregnancy have a greater risk of have a child with a number of congenital malformations including: neural tube defects such as anencephaly and spina bifida, cardiovascular anomalies, including septal anomalies, cleft lip and palate, anorectal malformation, limb reduction anomalies, and hydrocephaly.
Intrauterine fetal death
Gastroesophageal reflux disease
Fatty liver disease
Ischemic stroke is increased in both men and women who are obese. For women with a BMI greater than 30, the risk of ischemic stroke increases by 1.7 fold, while men with a BMI greater than 30 had a risk of stroke 2.0 times greater.
Carpal tunnel syndrome
Idiopathic intracranial hypertension
Many cancers occur at increased frequency in those who are overweight or obese. A study from the United Kingdom found that approximately 5% of cancer is due to excess weight. These cancers include: 
- breast, ovarian
- esophageal, colorectal
- liver, pancreatic
- gallbladder, stomach
- endometrial, cervical
- prostate, kidney
- non-Hodgkin's lymphoma, multiple myeloma
Obesity has been associated with depression. The relationship is strongest in those who are more severely obese, those who are younger, and in women. Suicide rate however decreases with increased BMI.
Obstructive sleep apnea
Obesity hypoventilation syndrome
Obesity hypoventilation syndrome is defined as the combination of obesity, hypoxia during sleep, and hypercapnia during the day, resulting from hypoventilation. Based on its definition it occurs only in the obese.
Chronic lung disease
Obesity is associated with a number of chronic lung diseases, including asthma and COPD. It is believed that a systemic pro-inflammatory state induced by some causes of obesity may contribute to airway inflammation, leading to asthma.
Complications during general anaesthesia
Rheumatological and orthopedic
There is a strong association between obesity and musculoskeletal pain and disability
Increased rates of arthritis are seen in both weight-bearing and non-weight-bearing joints. Those with a BMI greater than 26.4 had rate of osteoarthritis of the knees 6 times greater than those with a BMI of less than 23.4, well rates of osteoarthritis in the hand was about 1.5 times greater.
Low back pain
Obese individuals are twice to four times more likely to have lower back pain than their normal weight peers.
Urological and nephrological
Urge, stress, and mixed incontinence all occur at higher rates in the obese. The rates are about double that found in the normal weight population. Urinary incontinence improves with weight lost.