Introduction. The overweight and obesity epidemic represents a rapidly growing threat to the health of populations in an increasing number of countries. Nearly one-third of the world's population has excess adipose tissue. Nowadays, obesity occurrence is so common that it is replacing more traditional problems, such as an undernutrition and infectious diseases, as the most significant causes of ill health. If the current trend continues, almost half of the world's adult population will be overweight or obese by 2030. Objective. The aim of this study is to show the connection between recent trends in body mass index, and the globally changing cancer profile. State of knowledge. A range of clinical and epidemiological studies have shown the relationship between excess body fat and the most frequently occurring malignancies. Obesity is associated with many cancers, such as: breast, colorectal, liver, lung, kidney, oesophageal, pancreatic, endometrium, ovarian, prostate, thyroid, and gallbladder cancer. Conclusions. In the light of this information, the study supports the claimed statement that obesity is one of the major health problems of the 21st century. Considering the increase in the number of obese people worldwide, it is necessary to develop a strategy allowing to prevent it. Fighting against unhealthy lifestyle in order to reduce overweight and obesity in society may have an essential impact on decreasing the number of incidences of cancer.