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Spotlight on Asia

The rising burden

A paper from a paper published in the Journal of Obesity entitled ‘Rising Burden of Obesity in Asia’, reports that overweight and obesity have reached epidemic proportions in many Asian countries.

A paper from a paper published in the Journal of Obesity entitled ‘Rising Burden of Obesity in Asia’, reports that overweight and obesity have reached epidemic proportions in many Asian countries. Although these countries also face a the burden of obesity-related disorders such as diabetes, hypertension, and cardiovascular diseases, it has been found that these disorders develop at a younger age than in Western populations and are also manifested in childhood.

The report’s authors , Drs Ambady Ramachandran(India Diabetes Research Foundation) and Chamukuttan Snehalatha (Diabetes Hospitals, Egmore, Chennai, India), claim that the major factors are related to the lifestyle changes occurring due to rapid socioeconomic transition. Interestingly, Asian populations show several differences in genetic factors when compared with the white population, and they also have lower cut points for environmental risk factors. They recommend that national programmes to target public awareness, alongside educational and improved structural facilities to facilitate healthy lifestyle, are the keys to alleviating the economic and health care burden of the obesity-related disorders.

Asia

According to the researchers, in most of the Asian countries the prevalence of overweight and obesity has increased in the past few decades and varies between countries. South East Asia and Western Pacific region are facing an epidemic of diseases associated with obesity such as diabetes coming and CVD, and India whilst has the highest number of people with diabetes in the world with China a close second. Unfortunately, there are not systematic national data on prevalence of obesity available from any Asian country.
However, it is known that differences exist in its prevalence and countries and regions in Asia are at different phases of development: Vietnam and Indonesia are in the early stages of development; Japan, Singapore, Malaysia, and Hong Kong are at more advanced stages. Table 1 shows the prevalence of overweight and obesity in Asian countries in comparison with the USA. The highest rate of obesity in Asia is in Thailand and the lowest is in India, followed by Philippines Interestingly, China, once the leanest of populations, and is rapidly catching up with the West in terms of prevalence of overweight and obesity.

Under- and over-nutrition paradox

The relationship between obesity and poverty is complex and in many developing regions both obesity and under nutrition coexist mainly due to wide socioeconomic disparities. For example, in the Philippines more than 30% of pre-school and school children are underweight, less than 1% was overweight. Among adults, prevalence of underweight was 13.2% while the prevalence of overweight was 20.2%.In world’s poorest countries, poverty is associated with malnutrition and underweight whereas, in middle-income countries, it is associated with an increased risk of obesity and the authors note that some countries face a paradox of families in which children are underweight and the adults are overweight.
AM Prentice(International Journal of Epidemiology; 35;1;93–99;2006) termed this the ‘thrifty phenotype in which a low birth weight due to poor intrauterine growth followed by a rapid childhood weight gain promotes development of obesity and associated metabolic complications. Low birth weight and exposure to undernutrition in utero are common in some Asian populations, especially in India, where 30% of infants are underweight. It is estimated that 43% of preschool children in lower income countries are stunted. It was previously hypothesized that stunting was associated with inadequate availability of food and poor socioeconomic conditions did not allow for the expression of obesity.
However, it is believed that nutrition transition causes rapid shifts in the composition of diet and activity patterns and the subsequent changes in body composition could lead to considerable obesity over the next several decades.
The investigators note that other studies have also shown that nutritional stunting leads to many changes like lower energy metabolism, greater susceptibility to fat rich diets, reduced oxidation of fats, and impaired regulation of food intake, and they claim that more studies are required to understand the long-term relationship between obesity and nutritional stunting.
Asia has undergone considerable socioeconomic transition in the last three decades which has resulted in increased availability of food, better transport facilities, and better health care facilities. First seen in the urban populations, with improving socioeconomic scenario in the rural areas, the changes have been seen even among the urbanizing rural populations. Figure 1 shows the increasing trend in obesity among the urban and also in the rural population (>20 years) in Chennai, Southern India.
In a decade, prevalence of obesity had increased by 1.7-fold in the city and the prevalence of the overweight was lower among the urbanizing rural population, than in the urban areas. However, the rural population had a more rapid change as shown by nearly 8.6-fold increase in a period of 14 years (A Ramachandran, et al. Diabetes Care;31;5;893–898, 2008. A Ramachandranet al. Diabetes Research and Clinical Practice;58;1;55–60;2002, A Ramachandran, et al. Diabetologia;47;5;860–865, 2004).Research has indicated that the living conditions in rural areas had improved considerably (eg. transport facilities, medical care and food habits, educational status) and family income had dramatically improved which along with easy access to city and television watching resulted in changes in lifestyle, leading to significant increase in BMI as well as abdominal obesity in both sexes as compared to a similar study conducted in the year 1989.
The prevalence of overweight rose from 2% to 17.1% and the changing life style of the rural dwellers was found to be contributory factor for the rising rates of obesity and associated metabolic diseases such as diabetes. Figure 1 shows temporal changes in prevalence of obesity (≥25 kg/m2) among urban and rural Asian Indians.
The results are based on epidemiological data collected in urban population (figure 1a) and for rural population (figure 1b).In some of the developing countries studied, obesity, especially among women, is regarded as a sign of affluence and such a cultural influence could be related to the higher prevalence among women compared to their male counterparts.

Changing lifestyles

A significant positive correlation exists between the economic status and the composition of diet consumed. For example, in China, the average energy density of food has increased over the last decade in the urban and rural populations. Moreover, reduced physical activity at work due to mechanization, improved motorized transport and preferences for viewing television and video games to outdoor games during leisure time, have resulted in positive energy balance in most of the Asian countries. In Asia, automobiles are rapidly replacing bicycles as the primary mode of transport, with motor vehicle ownership in China and India increasing dramatically.

Childhood obesity

In parallel with the increase in adult obesity, obesity in children is also increasing, reaching more than 25% in many developing countries. Studies in India (Overweight ≥ 25 kg/m2, Obesity ≥ 30 kg/m2 using Cole’s criteria) Singapore, China, Malaysia (BMI ≥95thpercentile in both) and other Asian countries have shown a rising prevalence of obesity among children. Wang et al. (The Lancet; 366;9499;1821–1824;2005), showed that the rate of obesity among children aged7–17 years in big cities in China was more than 20%, whilst Li et al. (British Journal of Nutrition, 97;1;210–215;2007) reported a parallel increase of obesity with dietary fat and high energy consumption in Chinese children and that parental obesity was the most pronounced risk factor for childhood obesity among these children.

Adiposity in Asians: General adiposity

According to the researchers, Asian populations generally have a lower body mass index (BMI) than many other ethnic groups, but the association between MI and glucose intolerance is as strong as in any other population. The risk of diabetes (odds ratio) was significant for urban Indian populations with a BMI of >23 kg/m2 and this has been confirmed by studies from other parts of India. According to the WHO recommendations, a BMI of 18.5–22 kg/m2 is considered healthy for Asian populations.

Abdominal adiposity

The risks for diabetes and for CVD are associated with a lower BMI among Asian populations. Many Asian populations, especially south Asians, have a higher total and central adiposity for a given body weight when compared with matched white populations. A higher prevalence of metabolic syndrome in south Asians is mostly attributed to the higher prevalence of central adiposity. The International Day for the Evaluation of Abdominal Obesity (IDEA) study examined the average waist circumference of 30,000 individuals in three Asian regions and compared them with figures from a similar number of people in Northwest Europe. Data from three Asian regions, namely south Asia (India, Pakistan), East Asia (China, Korea, Taiwan) and south East Asia (Indonesia, Malaysia, the Philippines, Singapore, Thailand, and Vietnam) showed that obesity and abdominal obesity were highly prevalent in these countries, especially in south Asia.

As per the IDF criteria of waist circumference ≥90cmfor men and ≥80cm for women, prevalence of abdominal obesity in men and women were 58% and 78% in south Asia, 38%, and 51% in East Asia and 38% and51% in South East Asia compared to respective prevalence of 58% and 67% in the Europeans using cut off values of ≥94cm for men and ≥80cm for women, respectively. South Asians had the highest prevalence of abdominal obesity and women had higher rates than men. A higher prevalence of diabetes and CVD in Asian populations, especially in women could be attributed to the higher waist circumference, the authors noted. It has also been noted that for a given BMI, Asians have higher body fat percentage compared with Caucasians. The differences in anthropometric characteristics are evident even in Asian children who are shown to have higher body fat percentage at lower levels of bodyweight and also a tendency for abdominal obesity.

Obesity and insulin resistance: The role of adipose tissue

There is al so a strong genetic component for obesity. Obesity is associated with increased number and/or size of fat cells which overproduce hormones such as leptin, and cytokines like Tumour Necrosis Factor (TNF), some of which cause cellular resistance to insulin. Synthesis of adiponectin which enhances insulin sensitivity is suppressed and the activity of hormone-sensitive lipase is increased causing increased flux of non-esterified fatty acids (NEFAs), which in turn causes insulin resistance in the liver and muscle. Increased levels of NEFA lead to excess synthesis of triglycerides and cholesterol and cause other derangements in lipid metabolism. Compensatory hyperinsulin aemia maintains normo glycaemia but may cause retention of sodium and water through stimulation of sympathetic nervous system and cause increase in blood pressure. Excess secretion of TNF and other cytokines is associated with a proinflammatory state which also partially contributes to insulin resistance. Even though the genesis of obesity is associated with a strong genetic influence, a strong obesogenic environment is typically required for its phenotypic expression. Recent genome-wide studies have shown multiple loci on chromosomes which affect the obesity-related phenotypes. The authors state that more studies on the gene-gene and gene-environment interactions are required to clearly understand the aetiology of obesity.

Conclusion

In conclusion, the authors recommend that it is essential population-based strategies are implemented to improve social and physical environmental contexts of healthy eating and physical activity. They note that some countries including Pakistan, Singapore, India, and China have initiated national programmes related to obesity and nutrition, and Singapore’s ‘Fit and Trim’ programme resulted in a drop in prevalence of obesity from 16.6% in 1992 to 14.6% in 2000 among children aged 11 to 12 years, and from 15.5% to13.1% among children aged 15 to 16 years. The Ministry of Health, Malaysia and Academy of Medicine, Malaysia (2003) have laid down guidelines for reduction of overweight and obesity in children and adolescents. These include: reduction in energy intake by use of conventional food, improving physical activity and thus energy expenditure, behaviour modification associated with eating habits and activity pattern, and involvement of the family in the process of change.

Public education campaigns, warning on the ill effects of obesity and its related metabolic disorders can produce slow, but gradual impacts. However, the investigators claim that prevention of obesity is likely to be most effective when implemented in childhood. With many Asian countries, such as India, having to solve the coexistence of under- and over-nutrition, the researchers urge that serious governmental actions are required to reduce the health related problems and the huge economic healthcare cost: “There are several areas in which future research should be undertaken. Nationally representative and longitudinal studies are required to monitor secular trends, to study the usefulness of the current cut off values for predicting long-term health outcomes and also to examine the health and psychosocial outcomes of childhood obesity. Moreover obesity prevention will require better understanding of the causative factors for obesity which influence behaviour and the social and cultural environment.”

Source: Ambady Ramachandran and Chamukuttan Snehalatha, “RisingBurden of Obesity in Asia,” Journal of Obesity, vol. 2010