How does obesity trigger multiple systemic diseases? An analysis of risks from bone and joint problems to tumors.

Other Systemic Diseases:

(I) Osteoarticular Diseases
The mechanism by which obesity leads to osteoarthritis is not yet fully understood. It is possible that overweight increases the static and dynamic loads on the cartilage of weight-bearing joints, exacerbating wear and tear and causing changes in the internal structure of the joints, thus leading to disease. Osteoarthritis is most common in weight-bearing joints such as the knees and feet in obese patients, and its incidence and severity are positively correlated with weight and skin fat thickness. Increased mechanical pressure leading to biomechanical changes in joint structure is an important factor in osteoarthritis. However, while the hand joints are not weight-bearing joints, finger joint disease increases with weight gain; conversely, the hip joint is a weight-bearing joint, but hip joint disease is rare in obese patients. Therefore, being overweight is not the only factor causing osteoarthritis. Abnormal lipid and glucose metabolism may also contribute to osteoporosis or osteolysis.

Elderly individuals, especially obese patients, experiencing joint pain in specific areas without systemic symptoms should be considered for obesity-related osteoarthritis. Pain is relieved after joint rest; weight-bearing joints (hip, knee) are primarily affected; transient joint stiffness occurs upon waking; X-ray findings include narrowing of the joint space, osteophyte formation, increased subchondral density, and cysts, and no clear cause can be found, leading to a diagnosis of primary osteoarthritis.

The fundamental treatment for osteoarthritis in obese patients is weight loss, while surgical treatment is often ineffective.

(II) Gout The direct cause of gout is hyperuricemia. It can be caused by purine metabolism disorders due to hereditary or acquired factors, leading to elevated blood uric acid levels.

Clinical observations have found that obesity is one of the common comorbidities of gout. Recent population surveys have confirmed a positive correlation between blood uric acid levels and BMI. Some gout patients experience a reduction in the frequency of acute gout attacks after weight loss, and blood uric acid levels also decrease.

The mechanism by which joint obesity causes gout is not fully understood. Some believe that excessive long-term intake of high-protein, purine-rich foods leads to an increase in exogenous uric acid in the body exceeding the amount excreted by the kidneys, resulting in hyperuricemia. Uric acid then deposits as urate crystals, forming gout-related joint lesions, tophi, and gouty nephropathy, among other clinical manifestations of gout.

Weight loss remains the fundamental treatment for gout in obese patients. During acute gout attacks, medications such as colchicine, iodine, and allopurinol can be used, depending on the condition, to correct hyperuricemia.

(III) Gynecological Diseases
Obesity is associated with several gynecological diseases, including polycystic ovary syndrome (PCOS), infertility, and menstrual disorders. In adulthood, overweight and adolescent obesity are independent risk factors for reproductive system diseases.

Abdominal obesity is a particularly important risk factor for menstrual disorders and infertility; this localized obesity may increase masculinizing symptoms. Weight loss is particularly beneficial for obese women with PCOS, improving related hormone levels and menstrual irregularities.

(IV) Tumors
Obesity is closely related to an increased incidence of certain cancers. Obese men primarily experience an increased incidence of colon, rectal, and prostate cancer, while obese women have a higher incidence of endometrial, ovarian, cervical, and breast cancer. These cancers are all regulated by the endocrine system. Adipose tissue contains an enzyme called aromatase, which converts adrenal steroids in women into androgens and androgens in men into estrogen metabolites. Increased adipose tissue leads to elevated aromatase expression levels, and sex hormone metabolites control the effects of nutrition on these cancers.

(V) Acanthosis nigricans
Acanthosis nigricans is a rare skin disease characterized by hyperpigmentation, hyperkeratosis, and verrucous proliferation. Clinically, acanthosis nigricans is classified into five types: true, pseudo, drug-induced, malignant, and mixed. Pseudoacanthosis nigricans is mainly associated with obesity.

The pathogenesis of obesity-induced acanthosis nigricans is not yet clear, but it may be related to hyperinsulinemia and insulin resistance. Studies have shown that high concentrations of insulin can stimulate excessive growth of dermal spinous cells and fibroblasts, leading to the characteristic lesions of acanthosis nigricans.

(VI) Anesthesia and Surgical Risks Overweight patients face increased potential risks during anesthesia and surgery, including chest infections, incision infections, incision dehiscence, hernias, postoperative back pain, and thrombosis. These risk factors often hinder elective surgery in obese patients.

Some surgeries are also difficult to perform successfully in obese patients, such as knee replacement surgery in patients with arthritis. Open-chest and laparotomy surgeries are also high-risk, requiring assisted ventilation and enhanced postoperative support. For routine surgeries, the upper limit of BMI is generally set at 30 kg/m². If the BMI exceeds this value, the perioperative risks increase, necessitating a longer hospital stay.