Globally, more than a third of adults are overweight. 13% are obese. The prevalence of overweight and obesity nearly tripled between 1975 and 2016.
Perhaps even more worryingly, childhood overweight and obesity are increasing at a rapid rate. In 2016, 41 million children under the age of five were obese or overweight. This number is expected to be 70 million by 2025. Over 18% of children and adolescents aged 5–19 were overweight or obese, compared to just 4% in 1975.
The fundamental cause of overweight and obesity has long been thought to be a simple energy in — energy out imbalance, yet in truth the problem is far more complex, deeply rooted in food culture.
The “nutrition transition”, a concept based on the idea that profound changes in food culture result from societal shifts away from traditional lifestyles, was developed by Professor Barry Popkin in the early 1990’s. Amongst the wealthy, increased disposable income, facilitated by urban development and globalisation and coupled with the changing role of women as professionals outside the home, has created demand for a wider range of eating choices. Options such as dining out, takeaway (particularly fast food) and convenience meals are increasingly popular; despite the fact that they may be less nutritious and healthy than food prepared in a traditional fashion in the home. Meanwhile, lifestyles have tended more and more towards sedentarism. It is these social and cultural shifts to which overweight and obesity have been attributed in wealthy nations such as the USA and Australia.
However, overweight and obesity, along with the so-called “diseases of civilisation”, have more recently begun to permeate and take hold in middle and low income countries. Between 1991 and 2016, the number of overweight and obese children under 5 in the African region more than doubled, from 4 million to 9 million. Yet Africa is one of the poorest regions in the world. In wealthier countries, the rate of overweight and obesity prevalence is also growing at a faster rate amongst lower socioeconomic groups.
Something isn’t adding up.
When we think about malnutrition, typically we might think of undernutrition, characterised by wasting (low weight-for-height), stunting (low weight-for-age) and underweight (low weight-for-height-and-age).
Yet the World Health Organisation (WHO) also refers to micronutrient deficiencies or excesses and overweight, obesity or diet-related non-communicable diseases as issues of malnutrition as well. Often, they are inter-related and co-occurrent.
The overweight and obesity epidemic that’s quickly spreading through the global population appears to be largely driven by malnutrition in the form of micronutrient deficiencies. Often referred to as “hidden hunger” because it is not obvious to the eye of the onlooker, micronutrient deficiencies are a far more prolific form of starving than simply not getting enough caloric energy. Micronutrient deficiencies affect 2 billion people globally; less than a quarter of that number are underweight.
Among the poor, the changes in food culture and eating practices that result in hidden hunger are initially driven by economic pressure and accessibility issues.
In large part, this can be attributed to the increased prevalence of rural-urban migration. In the space of 118 years, the urban population increased from 10% of total global population to 55% of total global population. One of the factors driving rural-urban migration has been the displacement of small farmers as the trend towards large farms has taken hold. Meanwhile, rural communities have been decimated as the farming population has dwindled. Many rural landholders or non-farm rural residents have been forced to move to cities in search of steady income.
In other instances, neoliberal policies have paved the way for transnational food companies to become dominant in local food markets and created over-reliance on imported food products, the prices for which may be subject to wide fluctuations depending on the global market.
Unstable political situations also contribute to dietary changes through displacement and uncertainty.
And though agricultural industrialisation and the adoption of biogenic crop technology may have resulted in greater food production, the loss of food biodiversity and the monotony of diets largely reliant on grains — and just three types of grain at that — has exacerbated micronutrient deficiencies. It’s no coincidence that the highest rates of micronutrient deficiency occur in the country that gave rise to the Green Revolution.
The economic instability that has arisen from these rapid changes paired with fluctuating dynamics in local food systems has created widespread food insecurity.
Food insecurity tends to create a nutrition transition in its own right. Because of economic pressure, the afflicted seeks foods that are cheap yet will fill their energetic needs (and more). Access to nutritious, wholesome energy sources is limited by access and affordability; the most consistently available options are processed foods, high in sugars and unhealthy fats (please note that I do not say saturated fats). As new eating habits emerge around these cheap, nutritionally defunct foods, hidden hunger grows. Continually starved of the essential micronutrients that the body needs, an even greater hunger is fuelled. Feeding it with more of the same will eventually lead to overweight and obesity.
Aside from the obvious effects on physical health, food insecurity is problematic because of its links to negative mental health outcomes.
Inadequate nutrition leads to impaired cognitive development, particularly in the early stages of a child’s life. The effects can be long-lasting, diminshing cognitive capacity right through adulthood. Adults can also experience diminished intellectual incapacity as a result of inadequate nutrition.
The stress response invoked by food insecurity can, over time, lead to conditions including depression and anxiety, which may exacerbate existing physical health problems.
And the stigma associated with food insecurity and acquiring food in socially unacceptable ways may manifest in different ways. For example, adolescents with household food insecurity have been found to have higher rates of mental health problems in general, including conduct problems and problems in peer relationships.
The connection between mental health outcomes and food insecurity is particularly pertinent to overweight and obesity: this article in Nature (which is an absolute ripper, by the way; I highly encourage you to read it) shows that mental dysfunction often specifically co-occurs with overweight and obesity due to micronutrient deficiencies in diet.
For those who experience hidden hunger, it can be very difficult to break free. As mental and physical health declines, the financial burden of disease increases and food insecurity worsens further. The food insecure become trapped in the poverty cycle, a continuous downward spiral.
Even after hidden hunger has been alleviated, the effects on physical and mental health remain evident long-term. In this study, it was found that women who had experienced poverty-associated food deprivation in childhood were more likely to be obese or overweight in adulthood, and to actively avoid food insecurity. Some women had used food to fill emotional needs in childhood, a habit that stayed with them into adulthood. Additionally, their children displayed responses of excitement to food after a period of deprivation similar to that of their mother’s. Clearly, the effects of food insecurity are long-lasting not only in the afflicted but also in subsequent generations. A memory deeply etched into their behaviour and genetics.
I’m not going to offer any solutions to the problem of hidden hunger and overweight/obesity here. I think that they are far too complex to tackle in one article, though I have touched on many of the structural issues underpinning hidden hunger— and their solutions — in several other articles.
But I will say this: though hidden hunger stems from food insecurity, food insecurity is not really the true cause of our woes. Rather, it is a symptom of a more serious ailment: the disconnect that exists between ourselves — both as individuals and collectively — and the natural world, a disconnect that resonates deeply within ourselves. The overweight and obesity epidemic may be driven by hidden hunger, but it is a yearning for more than simply food. If we want to truly understand and face what’s ahead of us, we must undertake a deep, critical examination of not only what we eat, but the meaning and value that we attribute to food — and every other aspect of our lives.
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