The Asia-Pacific region is home to nearly half of the world’s population. The region has seen a recent rapid increase in the prevalence of obesity, type-2 diabetes and cardiovascular disease. The present systematic review summarizes the recent prevalence and trends of Metabolic Syndrome (MetS) among adults in countries of the Asia-Pacific Region. Data on MetS in Asia-Pacific countries were obtained using a stepwise process by searching the online Medline database using MeSH terms ‘Metabolic Syndrome X’ and ‘Epidemiology/EP’. For the purpose of describing prevalence data for the individual countries, studies that were most recent, nationally representative or with the largest sample size were included. When evaluating secular trends in prevalence in a country we only considered studies that evaluated the temporal change in prevalence between similar populations, prospective studies based on the same population or National surveys conducted during different time periods. This literature search yielded a total of 757 articles, and five additional article were identified by screening of reference lists. From this total, 18 studies were eligible to be included in the final analysis. Of the 51 Asia-Pacific countries (WHO) we only located data for 15. There was wide between country variation in prevalence of MetS. A national survey from Philippines conducted in 2003 revealed the lowest reported prevalence of 11.9% according to NCEP ATP III criteria. In contrast, the highest recorded prevalence in the region (49.0%) came from a study conducted in urban Pakistan (Karachchi, 2004). Most studies reported a higher prevalence of MetS in females and urban residents. Data on secular trends were available for China, South Korea and Taiwan. An increase in the prevalence of MetS was observed in all three countries. Despite differences in methodology, diagnostic criteria and age of subjects studied, the Asia-Pacific region is facing a significant epidemic of MetS. In most countries nearly 1/5th of the adult population or more were affected by MetS with a secular increase in prevalence. Strategies aimed at primary prevention are required to ameliorate a further increase in the epidemic and for the reduction of the morbidity and mortality associated with MetS.

Globally, obesity is affecting an increasing proportion of children. Physical activity plays an important role in the prevention of becoming overweight and obese in childhood and adolescence, and reducing the risk of obesity in adulthood. Puberty and the following adolescent period are acknowledged as particularly vulnerable times for the development of obesity due to sexual maturation and, in many individuals, a concomitant reduction in physical activity. In many Western settings, a large proportion of children and adolescents do not meet recommended physical activity guidelines and, typically, those who are more physically active have lower levels of body fat than those who are less active. Active behaviours have been displaced by more sedentary pursuits which have contributed to reductions in physical activity energy expenditure. Without appropriate activity engagement there is an increased likelihood that children will live less healthy lives than their parents. Owing to the high risk of overweight adolescents becoming obese adults, the engagement of children and adolescents in physical activity and sport is a fundamental goal of obesity prevention.

The ability to assess energy expenditure and estimate physical activity in free-living individuals is extremely important in the global context of non-communicable diseases including malnutrition, overnutrition (obesity) and diabetes. It is also important to appreciate that physical activity and energy expenditure are different constructs with physical activity defined as any bodily movement that results in energy expenditure and accordingly, energy is expended as a result of physical activity. However, total energy expenditure, best assessed using the criterion doubly labelled water technique, includes components in addition to physical activity energy expenditure, namely resting energy expenditure and the thermic effect of food. Given the large number of assessment techniques currently used to estimate physical activity in humans, it is imperative to understand the relative merits of each. The goal of this review is to provide information on the utility and limitations of a range of objective measures of physical activity and their relationship with energy expenditure. The measures discussed include those based on energy expenditure or oxygen uptake including doubly labelled water, activity energy expenditure, physical activity level, and metabolic equivalent; those based on heart rate monitoring and motion sensors; and because of their widespread use, selected subjective measures.

The metabolic equivalent (MET) is a widely used physiological concept that represents a simple procedure for expressing energy cost of physical activities as multiples of resting metabolic rate (RMR). The value equating 1 MET (3.5 ml O₂·kg⁻¹·min⁻¹ or 1 kcal·kg⁻¹·h⁻¹) was first derived from the resting O₂ consumption (V̇o₂) of one person, a 70-kg, 40-yr-old man. Given the extensive use of MET levels to quantify physical activity level or work output, we investigated the adequacy of this scientific convention. Subjects consisted of 642 women and 127 men, 18–74 yr of age, 35–186 kg in weight, who were weight stable and healthy, albeit obese in some cases. RMR was measured by indirect calorimetry using a ventilated hood system, and the energy cost of walking on a treadmill at 5.6 km/h was measured in a subsample of 49 men and 49 women (26–45 kg/m²; 29–47 yr). Average V̇o₂ and energy cost corresponding with rest (2.6 ± 0.4 ml O₂·kg⁻¹·min⁻¹ and 0.84 ± 0.16 kcal·kg⁻¹·h⁻¹, respectively) were significantly lower than the commonly accepted 1-MET values of 3.5 ml O₂·kg⁻¹·min⁻¹ and 1 kcal·kg⁻¹·h⁻¹, respectively. Body composition (fat mass and fat-free mass) accounted for 62% of the variance in resting V̇o₂ compared with age, which accounted for only 14%. For a large heterogeneous sample, the 1-MET value of 3.5 ml O₂·kg⁻¹·min⁻¹ overestimates the actual resting V̇o₂ value on average by 35%, and the 1-MET of 1 kcal/h overestimates resting energy expenditure by 20%. Using measured or predicted RMR (ml O₂·kg⁻¹·min⁻¹ or kcal·kg⁻¹·h⁻¹) as a correction factor can appropriately adjust for individual differences when estimating the energy cost of moderate intensity walking (5.6 km/h).