The changing lifestyle in the world. Body weight and what else?

Body weight and the prevalence of obesity are rising so rapidly in many countries that the World Health Organization has recognized that there is a "global epidemic of obesity." The prevalence of type 2 diabetes is rising in parallel. In view of its associated cardiovascular complications, we are facing a severe public health problem. Both obesity and type 2 diabetes have a combined genetic and environmental background, but the epidemic must be due to major changes in the environment. By definition, obesity is a result of a positive energy balance, which usually amounts to a tiny proportion of the total energy turnover. Energy intake, energy expenditure, and energy accumulation (as fat) may all be primarily disturbed. There is a great, and still insufficiently understood, variation in prevalence of obesity and in the rate of change of the prevalence. The prevailing contention is that the epidemic is due to the changes in the society--the so-called modernization--leading to overnutrition and a sedentary life. These factors are likely contributors, but it has been difficult to provide consistent evidence for their effects. In Denmark, a steep rise has taken place in the prevalence of obesity among schoolboys and young men in two phases linked to the birth cohorts of the 1940s and of the mid-1960s and later. This rise suggests that environmental influences operating early in life are involved. In conclusion, a global obesity epidemic is developing, but the causes of the epidemic are not yet clear and more research is needed to establish the grounds for prevention.