Mild to moderate primary obesity might not present with noticeable symptoms. However, individuals with severe obesity may experience heat intolerance, reduced physical activity capability, mild shortness of breath during activities, and snoring during sleep. The likelihood of developing coronary heart disease and hypertension is significantly higher in obese individuals compared to those who are not obese. Obesity leads to reduced lung capacity and decreased pulmonary compliance, which can cause various pulmonary functional abnormalities.

For instance, obese hypoventilation syndrome, clinically characterized by sleepiness, obesity, and alveolar hypoventilation, often accompanies obstructive sleep apnea. Severe cases of obesity may lead to pulmonary heart syndrome. Obese individuals often experience metabolic disorders of lipids and carbohydrates; lipid metabolism disorders can lead to hypertriglyceridemia and hypercholesterolemia, while carbohydrate metabolism disorders are marked by glucose intolerance and diabetes. Moreover, obese individuals are more prone to arthritis, gout, and osteoporosis.

Sexual dysfunction is common in obese individuals, with some obese men developing gynecomastia; obese girls tend to have an earlier onset of menstruation, while adult women with obesity often experience menstrual disorders, and in severe cases, amenorrhea. The incidence of polycystic ovary syndrome is also significantly higher in obese women compared to non-obese women.