Summary: In developed countries, including Poland, the prevalence of overweight and obesity is increasing and is currently one of the most common health-related problems associated with lifestyle. Since 1975, the number of people with obesity has tripled. According to the standards adopted by the World Health Organization (WHO), overweight can be diagnosed when the BMI is equal to or greater than 25, while obesity when the BMI is 30 and above. In 2016, over 1.9 billion adults in the world were overweight and over 650 million suffered from obesity. Most of the human population lives in countries where overweight and obesity causes more deaths than underweight. Overweight is associated with the higher risk of cardiovascular, metabolic, cancer, motor system disorders and respiratory diseases. The highest risk of death occurs in patients with BMI > 35. Moreover obesity may induce dyspnoea and reduced exercise tolerance, and may have a negative effect on the breathing mechanics in people with chronic respiratory disease - asthma and chronic obstructive pulmonary disease. Obesity can cause breathing disorders during sleep: obstructive sleep apnea (OSA), hypoventilation syndrome of obese people (OHS), which can lead to obesity-related respiratory failure (ORRF). Severe OSA and OHS is associated with higher morbidity and mortality. Proper diagnosis and treatment is very important. In order to avoid breathing disorders related to obesity and other complications, and thus all consequences for the health care system, normalization of body weight through dietetic, pharmacological and sometimes bariatric treatment is recommended. The challenge of the 21st century is prevention and education in the field of nutrition and healthy lifestyle in order to stop the pandemic of obesity.