Malnutrition targets the human being in three forms, undernutrition, micronutrient deficiency, and overnutrition. Overnutrition is also called obesity which is characterized as dietary intake which exceeds the daily requirements of the body (Hannah Ritchie, 2019). In 1993, World Health Organisation (WHO) undertook a broad review and interpretation of anthropometric references. In 2018, the global prevalence of obesity has gone threefold between 1975 and 2016. The prevalence of obesity among adults has been increasing in all countries. During 2016, around 1.9 billion adults were reported overweight, and out of these around 650 million were obese. In another study, it was reported that in 2016, about 39% of adults comprising 39% and 40% of men and women respectively were overweight. As a whole around 13% of the global adult population were obese. According to The National Health and Nutrition Examination Survey (NHANES, a growing trend in adult obesity from 1999–2000 to 2015–2016 was recorded however there is no significant shift in the incidence of obesity seen from 2013–2014 to 2015–2016, (Ogden, C. L., et.al., 2016). Developing countries experienced a more significant rise in the prevalence of obesity in recent decades. Surprisingly, the problems of overweight or obesity are increasing in countries where hunger is still endemic (Popkin BM, 2002).
In the last three decades, globally overweight has increased from 28.8% to 36.9% in men and from 29.8% to 38.0% in women, while obesity has increased from 3.2% to 10.8% in men and from 6.4% to 14.9% in women (Neuman M, et.al. 2013). The World Health Organization (WHO) has introduced a voluntary target to stop the increase in incidence and prevalence of obesity by 2025 (Wu Y, Zhai L, Zhang D. 2014). So far there is no country that has reversed the rise in obesity (Sachdev HS, et al. 2005).
· Indian scenario
Obesity in India is rising as an important health worry. This is an additional burden after the high prevalence of undernutrition. Overweight or obesity has been reported among 30-65% of the adult urban population (Misra A, Khurana L., 2008). Between the two National Health Surveys (NFHS-3 and NFHS-4), the prevalence of obesity has doubled in India. It has been reported that states with poor socioeconomic backgrounds (i.e. Jharkhand, Bihar, Madhya Pradesh, and Chhattisgarh) have a low rate of obesity prevalence as compared to states with higher socioeconomic status (i.e. Punjab, Delhi, Goa, Telangana, Andhra Pradesh, Puducherry, and Northeast states). The data of NFHS-4 and IIPS says the population of overweight or obese women has doubled in 2015-16 since 1998-99 (Shannawaz, M., et.al 2018). In the years 2015-16, around 20% of women were found overweight/obese compared to 10.6% in 1998-99 which was a considerable increase in less than two decades. In studies, education level has been depicted as a positively associated risk factor with the prevalence of overweight or obesity, however higher increase in the levels of overweight/obesity was also observed among illiterate or up to primary level educated women (Ahirwar, R., & Mondal, P. R., 2019). In 2019, The State of Food Security and Nutrition report released by the UN Food and Agriculture Organization (FAO), highlighted that number of obese adults in India climbed from 24.1 million in 2012 to 32.8 million in 2016.
Risk Factors of Obesity
There are plenty of risk factors for obesity. In this study, the researcher has tried to summarise the available findings in various literatures and strengthen the available evidence about risk factors.
1. Physical Activity
There is plenty of research available which supports that not doing physical activity due to numerous reasons including watching TV, working on computers or laptops, playing video games or other types of screen usage has been significantly associated with a high body mass index. (Robroek, S., et.al, 2013). Another researcher (Martínez-González, M,1999) said that there is a strong association between the physical inactivity of an individual with obesity. Diet and physical activity are two complementary drivers of obesity. In another study, it was said that excessive intake of calories due to changing food systems, rather than decreasing physical activity are among the biggest drivers of obesity (Swinburn et al. 2011).
2. Dietary Practices
Traditionally, obesity has been considered a consequence of continuous excess caloric intake (Je´quier E, 1999). Eating fast foods, eating irregularly, and skipping, breakfast or other meals are among the key contributors to obesity. Several studies have already reported that poor dietary practices which may be either extra calorie intake or skipping meals are associated with obesity. In a study, having asymmetrical consumption of meals or breakfast on weekdays was significantly associated with the increased risk of overweight or obesity among mid-adolescents. Future studies require to further examine dietary practices in the home environment in order to design interventions for reducing the risk of being overweight and obese (Sedibe, M. H., et.al, 2018). In another study, unfortunately, interventions aimed to alter the food selection and portion size to increase physical activity have not been able to result in long-duration weight loss and maintenance (Taheri, S. 2006). consumption of carbonated soft drinks was also associated with obesity in Mexican American children (Beck AL, et.al. 2014). In research among boys in Saudi Arabia, BMI was positively correlated with the consumption of sugar-sweetened carbonated beverages (Collison KS, 2010).
3. Sleeping Pattern and Sedentary Lifestyle
There are many types of research available and highlighted that increased BMI among people who do not get mandatory hours of sleep. Some studies have also shown the relationship between sleeping patterns and the body's use of nutrients for energy. It has also highlighted how lack of sleep can affect hormones in the body that controls hunger pangs. It is also said that sleep may not be the only response to obesity prevalence, however, it affects. Good sleep may be one of the prevention strategies for obesity (Chaput JP, 2006). The association between short sleep duration and obesity seems strongly associated among children. Avon's longitudinal study which was conducted in the 1990s among parents and children in the UK highlighted that the short sleep duration at an early age of 30 months increases the chances of being obese at age of 7 years. (Reilly JJ, et al. 2005). Findings from a systematic review of sedentary behavior and obesity risks were ambiguous owing to limited evidence from high-end studies (Torres SJ, 2007).
4. Stress
Acute and chronic degree of stress affects brain functioning and prompt the production of particular hormones which controls the energy balance and hunger. At the same time, acute stress also prompts hormones that change the body's functioning and discourage appetite. This review indicates that the presence of stress may lead to energy imbalance and cause overweight or obesity. In a study (Sinha and Jastreboff 2013) it was highlighted that stress is a common risk factor for obesity and can induce appetite and indicated that stress could lead to obesity not only by increasing food intake but also through different food choices and lowering appetite. One of the studies concluded recent literature and said there are significant relations between stress and obesity. This can be somewhat traced back to a third key player affecting stress and obesity (Tajik, E., 2014). Future studies may generate more insight into the ferocious circle of obesity, and stress, which may lead to the design of tailor-made treatment strategies (van der Valk, E. S., et.al. 2018).
5. Smoking and Drinking
There is a dearth of agreement on the association between smoking and obesity which may or may not be causal. Possible mechanisms include reduced calorific intake due to other behavioral factors, changed smell, impaired taste, or changes in food inclinations. The metabolic effect on absorption or storage of calories also seems associated with overweight and obesity (Cabanac M, 2002).
6. Socio-Economic Condition
Socioeconomic status (SES) and its role in the growth of obesity in developing countries is a matter of debate which is on. Traditionally overweight or obesity has always been considered a disease of upper-class people (Solomons NW, Gross R. 1995) but available evidence shows that the burden of obesity is now shifting to lower SES groups ( Monteiro et al., 2004). In the study, it was also found that when GDP per capita is more than $2,500 per annum, poverty is inversely associated with overweight and a load of overweight shifting from wealthy to poor. In addition to changing the prevalence of overweight, SES also influences the type of obesity. Furthermore, inequality in income also influences the prevalence of obesity. Another study found that a high level of income disparity was correlated with increased obesity, irrespective of national wealth (Wilkinson & Pickett, 2006). In a study, it was found that income inequity also reduces the association between economic development. The specific drivers of the disparate increases in overweight among lower-income groups are still unclear (Jones-Smith et. al., 2012).
7. Gender Differences
When it comes to women in low and middle-income counties, they carry an imbalanced burden of obesity (Martorell R, Khan. et.al, 1998). In 119 out of 130 Low and middle-income countries, women had a higher overweight or obesity prevalence as compared to men, where 9 out of 11 countries where men had a higher prevalence of overweight or obesity than women in Africa (Omran AR. 1971). In another study related to women of reproductive age, it was reported that overweight was growing at a larger rate in rural areas as compared to urban areas in nearly half of Low and middle-income countries.
8. Urbanization and Economic Development.
In one of the studies done in 2014, it was said that people living in urban areas of low, lower-middle, and upper-middle-income countries are accounting for 33%, 39%, and 63% respectively (World Urbanization Prospects, 2014 Revision). Obesity is normally higher in the urban regions as compared to rural settings across Low and middle-income countries. However, the prevalence of overweight and obesity soared globally while the obesity differences in urban and rural settings started shrinking because of urbanization of rural areas like changes in the transportation system, employment status, increase in income level, access to food markets, and other infrastructural development. These acted as triggers and accelerated obesity in semi-urbanized or rural areas in addition to economically developed areas (Suchday S, et.al, 2006). Urbanization has also become one of the barriers for people to be physically active due to availability and access to transportation and engagement in occupational activities (Caballero B, 1997).
9. Globalization and Food Environment
Globalization plays important role in the nutritional outcome of an individual by having access to the food market, and environment due to easy imports of food (Hawkes C, Thow AM. 2008). Still, more research is required on the factors that influence food choice apart from the effect of globalization. The urban food environment is exemplified by easy availability and access to high calories and cheap foods (James P, et al., 2013). Portion size is also one of the key determinants of energy intake. Nowadays larger than appropriate sizes of meal or food packs changes the dietary habits of an individual which further increases the risk of weight gain. The trend toward increasing portion sizes initiated in the late 1970s and has been increased the spread. However, currently, this is best documented in the United States only. Here portion sizes of various food products are becoming bigger in restaurants and fast food chains (Young LR, 2002).
10. Environmental Exposures
Geography has been considered as one of the factors in environmental exposure, as obesity changes according to geographical distribution due to the environment. West countries have a higher prevalence of obesity among adults while Midwest counties have a high incidence of diabetes and Cardiovascular disease, which come along with obesity (Gurka MJ, 2018). Numerous pieces of evidence highlighted that obesogenic environments support the development of obesity. However, it was also seen in the same population and communities, even after sharing the same obesogenic environment, many individuals do not get affected by obesity (David Albuquerque, 2017). Artificially prepared chemicals which are generally used as agricultural fertilizers and insecticides for mosquito control were mostly restricted in developed countries from 1970–the 1980s but are widely used in many developing countries and affect the production of cereals and vegetables. Contents also affect the health of individuals. Other insecticides like dichlorodiphenyltrichloroethane (DDT) are still used for malaria control in many countries such as India and the African continent (Van den Berg H, et al. 2012). These chemicals have become resistant to the natural environment and it is biomagnified in hotel industries. Consuming foods in such food markets accumulate biowastes in human tissues and causing not only obesity but many other diseases.
11. Genetic Factors
The idea genetic cause of obesity was first suggested by Von Noorden in 1907 and it was investigated continuously. (Chin J., 2014). The Harvard School of Public Health (HSPH) highlighted that genetic factors offer a smaller risk for obesity. However, another source from CDC says that people’s weight reacts to similar environments suggests, that genes also play an important role in the growth of obesity. It is also seen, that people who carry genes linked with obesity do not become overweight or obese, and vice versa (Timothy J. Legg, 2016). This is due to the fact that other factors also influence the risk of obesity. The heritability of BMI is estimated to be around 40%–70% (Allison DB, et.al, 1996) through control of the physiological response to high caloric and regulation of hunger through leptin hormones (Asai M, et al. 2013). Obesity is considered as a multifactorial disease in which environmental and genetic factors interrelate (Clement, K., 2002).
12. Pregnancy
Attaining more than the recommended weight during the period of pregnancy put women at higher risk of becoming obese and developing other health problems (University of Bristol, 2011, May 19). However, in a few other studies related to birth weight, also it was reported that the relationship between maternal weight and birth weight did not correlate with each other (Rossner, S. and Ohlin, A., 1995).
13. Occupational Hazards
There is plenty of evidence available that obesity and overweight is directly or indirectly related to adverse work conditions. In particular, the risk of obesity increases is associated with poor work environments. There are factors like stressed working culture, long working hours, and poor ergonomic facilities. An employee spends a quarter of their lives at work and the work pressure and demands of work affect their dietary habits and daily routines as well, which further leads to overweight and obesity (Yamada Y, et.al, 2002). However, evidence on this aspect is limited and further research is required to examine the effects of occupational engagement including organizational behaviors with obesity, and how the work environment either promotes or discourages obesity development (Schulte, P. A., 2007).
14. Diseases and Drugs
Centre for Disease Control & Prevention (CDC) on its website quoted that several types of ailments lead to overweight and obesity. Some of these include Cushing’s disease and polycystic ovary syndrome. Many drugs like steroids and antidepressant medicine also cause weight gain. The role of medicine and the certain disease continues to emerge as one of the risk factors in energy balance and weight gain due to chemical exposures and the role of the microbiome. Not only the weight gain as such puts a burden on the health risks of the involved patients. In one of the review papers, various classes of drugs with considerable weight-gaining properties and metabolic effects have been detailed. Antipsychotic drugs have been identified as one of the drugs causing weight gain (Verhaegen, A.A., 2017).
Conclusion
In this literature review, research has gone through more than 100 of research papers pertaining to obesity in various geographic regions and found the common risk factors, however, there is huge scope to explore further and identify the causal relationship. In one of the researches (Subrata Kumar Palo, 2019), it was highlighted that there is a paucity of obesity-related studies, especially in the rural populations of India. Future research can help us find more perspectives in obesity. Obesity will be the topmost priority among all public health agendas globally for many years to come, as solutions in recent coming years seem out of sight. The complexities of the issues that are into account for influencing the epidemic (National capital, government policy, Social norms, the built environment, genetics, and other factors of food preferences and biological mechanisms that regulate the motivation for physical activity and lifestyle) require a very complete package of approaches to combat the obesity (Veronika J., 2004). Table-1
The Centre for disease control & Prevention (CDC) has stated that obesity is a complicated health problem and it originates from a combination of risk factors such as lifestyle, behavior, and genetics. Behaviors include dietary patterns, physical inactivity, a sedentary lifestyle, medication use, and other exposures. Additional contributing factors are the built environment, education, and government policies. Although genetics and environment is the factors beyond our control, fat accumulation and energy balance can be regulated through individual and social efforts. Maintaining an appropriate energy balance of food intake and physical activity is a crucial preventive measure (Hoffbauer KG, 2002). Concluding this study, research has categorized the risk factors into modifiable and non-modifiable risk factors in table 1. Future research may require investigating what approach works when it comes to targeting the risk factors in order to reduce the prevalence of obesity, especially in the Indian context.
Through literature review, research scholar has organized all the risk factors causing obesity directly or indirectly. This paper will contribute to and become the basis in writing the chapters in my Ph.D. The thesis in detail highlights the risk factors of Obesity.