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Obesity in China: Causes and solutions

Levine, James A.

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In the world between 1 and 2 billion people have obesity.1 In the United States, which has the highest obesity rate in the world, one in three people have obesity.2 Obesity rates are increasing in every country in which it has taken hold.1 Obesity rates also affect all ages from the growing elderly-obese population3 to the dramatic increase in pediatric obesity,4,5 for example in the United States it is predicted that by the end of the decade one in two US children will have obesity. Obesity similarly affects all races and both sexes.6 As a consequence of the co-morbidities of obesity and of the associated costs such as days off work, obesity costs the US economy about 100–200 billion dollars per year.7

OBESITY IN CHINA

One in five of the people with obesity in the world are Chinese.8 There are distinct elements of obesity as it relates to Chinese people.

China's first nutrition and health survey was completed in 2002.9 It was the largest such survey ever conducted and included more than a quarter of a million people. The survey showed that in China between 1992 and 2002, more than 60 million people became obese. The biggest problem is in China's cities where 12% of adults and 8% of children have obesity. The data trends strongly suggest that obesity rates are likely to increase.10–13 This is supported by the data that 23% of the Chinese population is overweight; for example, in Beijing alone 60% of adults are overweight and one in three children are overweight. Today there are more than 200 million people in China who are overweight or obese (184 million overweight, 31 million obese).8,14 By 2020 it is predicted that there will be more people with obesity in China than in the United States.

The first question is what should be the definition of obesity for China. Because of its ease of implementation, body mass index (BMI) (weight in kg/height in msquared) is universally used as an index of overweight and obesity. Although BMI is not ideal for assessing an individual patient's obesity, BMI is useful in population studies15 as the only equipment needed is an accurate and precise weighing scale and an accurate height measure (standiometer). In the Chinese population16 it has long been suggested that the BMI-based definition for obesity showed be lower than for a European or North American populations17 where obesity is defined as a BMI of 30 kg/m2 or greater. The reason for this is18 because obesity-associated metabolic complications occur at lower BMI's in Chinese people compared to in European/North American populations; since obesity is defined as the statistical point at which obesity-associated complication rates accelerate for a population, the definition of obesity for the Chinese population should match the BMI-specific and population-specific complication rates.17,19,20 Overall, the consensus is that BMI cut-offs for obesity showed be lower in China whereby over-weight was defined as BMI of 24–27.9 kg/m2 and obesity was defined as BMI >27.9 kg/m.2,21,22

The predisposition of Chinese people to the metabolic complications of obesity appears to span the gamut of obesity-associated complications.23,24 For example, Chinese people are predisposed to develop glucose intolerance, diabetes,19,25,26 coronary artery disease,27,28 hypertension29 and hyperlipidemia30,31 at lower BMI's compared to European/United States' populations. Furthermore, other obesity-associated complications may be particularly common in China; for example population studies suggest that obstructive sleep apnea,32,33 is commonplace possibly because of population-specific craniofacial and upper airway morphology.34 Certain obesity-associated cancers too, may be common in China and this may relate not only to genetic factors but also to specific environmental factors such as diet.35,36 Overall, these associations explain the upswing of mortality rates that are associated with obesity in China37 and heighten the importance of intervening assertively in China's obesity crisis.13

The appearance of metabolic complications, in particular, in association with obesity in Chinese people is likely to reflect their predisposition to truncal (or “central”) obesity.38 In fact several authorities have suggested that carefully measured waist or waist-hip ratios might be more sensitive indices for obesity in China.5,33,39,40 Although, these measurements may render weight data more specific for Chinese populations and subpopulations,41 it is recommended to continue to use BMI as a base-measure in China42,43 as it represents a well established national and international15,44,45 index of weight status; it might then be of value to consider adding an appropriate measure of body fat distribution to increase the quality of obesity-risk surveillance in China.41,46

There are other factors that may predispose the Chinese to obesity-associated complications; for example, genetic variables specific for the Chinese population may be important co-variables that impact the likelihood that a Chinese person with obesity has obesity-related complications.47–50 Also, specific and rapid changes in diet and activity may be driving accelerated obesity emergence throughout China.42,43

Thus, obesity-associated complications impact Chinese people at lower BMI's than their European or American counterparts for a variety of reasons in particular the predisposition of Chinese people to accumulate truncal body fat.51

Why is it so devastating that obesity rates have increased 30-fold in 15 years in China? This is not only because of the impact obesity on physical health as described above, but also the effects of obesity on mental health52,53 and on the growing Chinese economy.54,55 In essence, obesity affects every organ in the body and affects every aspect of daily life. For example, already 100 million people in China have high blood pressure and 26 million people have diabetes and these numbers are likely to double by 2030 as obesity takes hold;14 every day in China, 3000 new diabetics are diagnosed.14 The economic impact of obesity on the growing Chinese economy has not yet been estimated but using the US cost-equivalents, obesity is already costing China many billions of US dollars each year.54,55 What is of greater concern still, is the vast number of Chinese children and youth56–60 that have obesity. Moreover, possibly in the same way that Chinese obese adults are predisposed to early complications from obesity, so too Chinese children39 appear to show early signs of obesity-associated complications such as hyperlipidemia,31 diabetes,61 hepatic steatosis62 and obstructive sleep apnea.61 Furthermore the common link between obesity and depression has already been made in obese children in China.57 The consensus is that China is on the brink of an obesity catastrophe unless childhood obesity is ameliorated.

OBESITY CAUSES

By the law of conservation of energy, body fat increases when energy intake is consistently greater than energy expenditure. Excess body fat and obesity are the result of sustained positive energy balance. The urgency to understand why humans are gaining weight has intensified.

It is accepted that nutritional quality is often poor.63 In fact China's first nutrition and health noted the dramatic change in nutritional quality with economic growth.9 However, there is controversy as to whether increased energy intake has accompanied the obesity epidemic. For example in Great Britain obesity rates have doubled since the 1980's yet energy intake appears to have decreased.64 The NHANES surveys in the United States are difficult to interpret because the method used to examine energy intake changed between surveys.65,66 In the absence of firm data that links increased dietary intake to obesity,67 the role of energy expenditure in human energy balance has come under greater scrutiny.

Classically, there are three components of human daily energy expenditure. The components of human energy expenditure are basal metabolic rate, the thermic effect of food and activity thermogenesis. Basal metabolic rate is the energy required for core body functions and is measured at complete rest without food.68,69 It accounts for about 60% of daily energy expenditure in a sedentary person. Nearly all of its variability (-80% of the variance) is accounted for by body size - or more precisely lean body mass - the bigger a person, the greater their basal metabolic rate.70 The thermic effect of food is the energy expended in response to a meal and is that associated with digestion, absorption, and fuel storage.70,71 The thermic effect of food accounts for about 10% of daily energy needs and does not vary greatly between people. The remaining component, activity thermogenesis can be sub-divided into exercise and non-exercise activity thermogenesis (NEAT).

Daily energy expenditure varies substantially.72 In fact highly active people expend three times more energy per day than inactive people72 and this marked variability in daily energy expenditure is even greater when data from non-industrialized countries are considered.73,74 Overall, for two adults of similar size, daily energy expenditure varies by as much as 8368 kJ/d (2000 kcal/d). As noted above, basal metabolic rate is largely accounted for by body size and the thermic effect of food is little. Thus, activity thermogenesis must vary by approximately 8368 kJ/d (2000 kcal/d). If activity thermogenesis varies by 8368 kJ/d (2000 kcal/d), is it because of exercise or is it because of NEAT? Exercise is defined as “bodily exertion for the sake of developing and maintaining physical fitness” for example sport or, visiting the gym.75 The vast majority of world-dwellers do not participate in exercise, as so defined and for them, exercise activity thermogenesis is zero. Importantly too, the vast majority of “exercisers” participate in exercise for less than two hours/week and for them, exercise accounts for an average energy expenditure of less than 418.4 kJ/d (100 kcal/d). On an aside, exercise is associated with massive health benefit including diminished diabetes, heart disease, and maybe cancer and is associated with prolongation of life-span76 and the converse appears to be true for inactivity.77 One wonders whether exercise is a modern surrogate for the hunter-gatherer or agriculturist life style. If so, high NEAT might confer massive health benefit and longer life. Overall, for the vast majority of people, NEAT must explain why an active person can expend 8368 kJ/d (2000 kcal/d) more than an inactive person of the same size.

NEAT is the energy expenditure of all physical activities other than volitional sporting-like exercise. NEAT includes all those activities that render us vibrant, unique and independent beings such as going to work or school, gardening, socializing, dancing, playing a musical instrument, swimming or cycling to work. NEAT is expended every day and can most easily be classified as NEAT associated with occupation and NEAT associated with leisure. Occupation is a key determinant of NEAT. If an average person were to go and work in agriculture, their NEAT could theoretically increase by 6276 kJ/d (1500 kcal/d).74 Variability in leisure78 also accounts for substantial variability in NEAT.79 Consider that an office worker returns home from work by car at 5 pm. From then until bedtime at 11 pm the primary activity is to watch television. For these six hours, the average energy expenditure above resting would approximate 8% and the NEAT will thus approximate 126 kJ for the evening (0.08*6276bmr*(6/24) hours). Now imagine he/she becomes aware of the unpainted bedroom, the weeds growing in the garden, at the possibility of cycling to work (rather than driving in a car). The person then decides to undertake these tasks. The increase in energy expenditure would be equivalent to walking approximately 1–2 miles per hour for the same period of leisure-time (5–11 pm). NEAT then increases to 3138–4707 kJ for the evening ((2 or 3)*6276bmr*(6/24) hours). Thus, for this hypothetical office worker, the variance in leisure-time NEAT has the potential of impacting energy expenditure by up to 4184 kJ/d (1000 kcal/d). Therefore, non-exercise activity varies by as much as, 8368 kJ/d (2000 kcal/d). This is because some occupations are far more energy expending than others and, because leisure activities range from almost complete rest to those that are highly energized. Since NEAT varies by 8368 kJ/d (2000 kcal/d), could NEAT be important in weight gain?

In humans, the manipulation of energy balance is associated with changes in NEAT. In one study,80 12 pairs of twins were overfed by 4184 kJ/d (1000 kcal/d). There was four-fold variation in weight gain, which by definition must have reflected substantial variance in energy expenditure. Since the changes in energy expenditure were not accounted for by changes in basal metabolic rate, indirectly changes in NEAT were implicated. Interestingly, twinness accounted for a substantial minority of the inter-individual variance in weight gain suggesting that NEAT is both under environmental and biological/genetic influences. When positive energy balance is imposed through overfeeding, NEAT increases.81,82 Moreover, the change in NEAT is predictive of fat gain.83 Those who with overfeeding increase their NEAT the most, gain the least fat. Those who with overfeeding do not increase their NEAT, gain the most fat. Therefore NEAT is fundamentally important in human fat gain.

If people, who fail to increase NEAT with overfeeding gain excess body fat, could there be a NEAT defect in obesity? To examine this question, micro-sensors were integrated into undergarments. These sensors allowed body postures and movements, especially walking, to be quantified every half second for 10 days. The data demonstrated that obese subjects were seated for 2 and a half hours per day more than lean subjects. The lean sedentary volunteers stood & walked for more than 2 hours per day longer than obese subjects. Importantly the lean subjects lived in a similar environment and had similar jobs compared with the obese subjects. If the obese subjects were to adopt the same NEAT-o-type as the lean subjects, they might expend an additional 1464 kJ/d (350 kcal/d). Thus NEAT and specifically walking are of substantial energetic importance in obesity. Lean individuals exploit opportunities to walk, where the obese find opportunities to sit.

Thus, obesity is associated with a NEAT-defect that predisposes obese people to sit.84 Lean people have an innate tendency to stand and walk. Overall, it is likely that there is a numerically substantial NEAT defect in obesity. This may reflect a hitherto ill-defined biology whereby those with obesity have a greater likelihood to respond to sedentary cues to sit.

How did obesity emerge over only 150 years and why obesity is rapidly increasing in China? Two million years ago early humans emerged from the forests of Africa as knuckle-walkers. The fossil evidence is abundant that over the last million years, an evolving homo sapiens stood more erect and walked across the earth. As our ancestors walked across the earth we populated it. This ambulation enabled us to find nutrition and shelter so that the species could be perpetuated in the presence of adequate fuel and in safety. This time course of a million years is consistent with the calculated, spontaneous mutation rate in DNA. Thus, a fundamental feature of humans is their requirement to walk.

Two hundred years ago, 90% of the world's population lived in agricultural regions. Much like our distant ancestors, they walked to work, had active work and walked home at the end of the day. Even, 100 years ago our great-grandparents did not watch television, did not surf the internet and did not play video games. Over the last century and especially over the last 20 years, there has been an unprecedented shift in the human demographic. Now half the world's population live in cities and half the worlds' population work predominately behind a computer. In so doing, a modern person sits during their drive to work, sits all day at work, sits to drive home and sits in the evening watching television, surfing the internet or playing video games. This is happening across modern China. In only 20 years car ownership85 has increased 500% in China and urbanization is occurring dramatically.

From this information we can understand the cause of human obesity. In Figure A the time-lines for energy intake and energy expenditure are displayed. Over 1–2 million years, energy intakes matched daily energy expenditure and most people were lean. This degree of energy intake was sustained even with industrialization, urbanization and mechanization. It could be argued that, with modern living, as tools-of-convenience became common-place, high-convenience food evolved too. In so doing, it was easier to retain ancient energy intake levels despite the substantial decline in day-time physical activity (Figure A).

Figure.
Figure.:
Obesity causation. A: The theoretical relationship of energy intake and energy expenditure in the emergence of obesity over the last century. B: The key elements to halting obesity in China.

Obesity occurred because with modernization there is a massive decrease in daily activity and the calories expended but food intake did not decrease at the same time. An analogy is of a bank account. If for many years a person spends exactly what they earn they will have no savings. If times change and the person spends much less money and keeps the same income, not all the money will be spent and savings will accumulate. This is what happens in obesity but for the body, these savings are as body fat. Obesity is sweeping through China because people are expending fewer and fewer calories through modernization but are not decreasing energy intake at the same rate. As a result body fat and obesity are occurring. One in five people who have obesity in the world live in China. By the end of 2020, more people in China will have obesity than in America.

STRATEGIC PLANNING TO HALT OBESITY IN CHINA

How can obesity be halted in China? In the US strategies are falling in place with a goal to end obesity. In America this struggle however is far more difficult as obesity is already deeply ingrained in society; it is now normal to be overweight in America, for example. In China the opportunity exists to half obesity before this occurs. Halting obesity has three components (Figure B).

Organization

Obesity solutions require organization. In the United States there are approximately 57 000 obesity programs with their own leadership and resources. These programs are not organized. There needs to be a system for resource sharing, universally recognized evaluation tools or defining the standard for “success”. It is interesting to compare the obesity efforts with the technology industry which has a similar growth rate to the obesity epidemic. In technology development there are uniform protocols that are used for example for data transfer and programming; Bluetooth and HTML are examples. The fact that multiple commercial entities agreed to share common protocols does not limit the range of products but actually helps sell more products because this enables different technologies to be integrated. For example, many brands of cell phone work on one network, one software program can work on many different computer models and a new cell phone easily replaces the old one. It is clear that even in the highly competitive technology industry the consumer benefits by competing companies being organized and sharing common operational systems and protocols. In obesity we need to organize a similar series of protocols that allow obesity interventions (personal or population) to be evaluated and compared in a common scientific-language. In so doing a “successful” program can be distinguished from an “unsuccessful” one. This will result in ineffective solutions being caste aside and the more effective solutions being refined and improved upon. National and international registries of successful obesity solutions will emerge, be independently verified and refined so that optimization of obesity intervention results. A National Center would define and organize effective culturally-specific national obesity solutions, precipitate programs for change and mediate international co-operate. Organization is crucial.

Once organization occurs cooperation needs to follow whereby a single voice emerges from the scientific community. It is straightforward for the major scientific bodies such as the cardiovascular and diabetes organizations to share a vision, resources, opinions and political petitioning. This avoids duplication, which is common at present in the United States. This consensus provides a clearly defined scientific knowledge base. Modern informational technology exists to build real-time expert texts on obesity etiology, biology and treatment. Consensus of scientific opinion could then be exploited to bring other partners to a shared position. Such partners for change include architects, the food industry, clothing manufacturers, the pharmaceutical industry, media companies, furniture companies and health insurers. Thus organization and establishing a clear and unified voice is the first step to solve obesity.

Define models of success

The second component for resolving obesity is that models of success need to be defined. Many people believe that obesity represents succession of poor personal choices. However, why would 1–2 billion people chose to have obesity, metabolic and joint disease, experience social stigmatization and psychological torment whereas they did not a century ago?

It is clear that obesity solutions must not only invoke personal action but also population-wide environmental reengineering to directly promote day long physical activity and healthy eating. Just as individual solutions are examined for weight loss, similarly population wide-models need to be devised and evaluated. New-style offices and activity-promoting schools not only appear to improve productivity but also increase daily activity levels.

To establish successful models of obesity resolution we must marry successful systems for personal-reinvention with environmental re-engineering. Defining successful models for obesity reversal will require both elements to be combined.

Each year obesity costs the US economy $150 billion dollars and so necessitates a billion dollar response. Billion dollar sums will be used to define multi-layered optimum cost-effective obesity solutions. It is crucial that successful obesity solutions need to be financially advantageous. In this regard it is essential to understand two facts. National obesity rates mirror economic status. This is true when comparing countries; richer countries have more obesity. This is also true over time; as a country becomes more wealthy, obesity rates increase. Thus the language of obesity solutions must speak to its economic consequences. In one example, an aggressive healthy office program is associated with decreased diabetes medications and fewer days off work. The program saves the company money because diabetic patients' medication costs decrease. Here the healthy office is not only effective for the employees' obesity and diabetes but is also cost-saving. As a result there is mutual interest between business owners and employees to introduce these programs. Successful obesity solutions must be economically viable. In a longer term view, if health enhancing schools decrease diabetes predisposition, this may render them cost-effective for the government, in the long-term. The expense-return algorithms are complex and vary, but a positive economic balance sheet is an essential part of the obesity solution. Obesity was created by wealth and successful obesity solutions cannot destroy this wealth.

Implementation

The third component in an obesity solution is implementation. Many people believe that obesity cannot be reversed. This is untrue. History repeatedly demonstrates that profound societal change can be affected; China has repeatedly proven this. Less than 150 years ago in England and America, slaves from Africa were legal, and today a presidential candidate is African American. History repeatedly demonstrates that societal change is achievable. History also dictates that movements that effect social change are always multidimensional. The collective determination of scientists, politicians and the populous therefore needs to converge. History is clear; major societal issues can be resolved using well-established consensus, clear and effective strategies, and multilayered, multidimensional solutions. Once effective solutions have been defined, it takes skilled, forward-thinking leadership and national will to implement them. Implementing obesity solutions is possible with strong leadership that is focused on the health of the people.

CONCLUSION

Obesity occurs as people become less active with industrialization and modernization. With this sharp decline in activity, energy expenditure decreases. Food intake should also decrease but it does not partly because of the temptations of high fat, sweet food. In America, it is now normal to be overweight and by the end of this decade most children will be obese. In China obesity is rapidly and aggressively taking hold. It needs to be stopped. The movement to achieve population-wide weight loss starts with a single step just as the Great Wall of China started from a single brick. Every family is touched by the pain and ill health of obesity and thus its solution is worthy of our collective commitment, investment and unending resolve.

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