Do social and mental-health factors contribute to malnutrition?

Do social and mental-health factors contribute to malnutrition?

Being overweight is one of the key drivers of hypertension, diabetes, cancer, stroke and heart disease in South Africa. While genetics play a role, research has also shown associations with social factors, the environment, education and mental health. Analysing data from the first South African National Health and Nutrition Examination Survey, the HSRCs Dr Whadi-ah Parker and a team of researchers from South Africa and Sweden looked at the effect of social and mental-health factors on malnutrition in South Africa.

A woman prepares food in Kanana in Gugulethu, Cape Town. In South Africa, married women are expected to cook and dish up large food portion sizes. If this food is high in simple sugars and saturated fats, it can fuel conditions such as type-2 diabetes and cardiovascular disease.
Photo: Yassey Booley

More than two-thirds of South African women and almost a third of men are either overweight or obese, an epidemicthat has spiralled over the last few decades. According to the South Africa Demographic and Health Survey 2016, most women who described themselves as having a normalweight were in fact overweight or obese. Only 3% of women and 10% of men were underweight.

International studies have shown that social factors may contribute to the obesity epidemic, but the findings have been contradictory. In an attempt to explore these factors in the South African context, researchers at the HSRC, the University of the Western Cape and Stellenbosch University collaborated with Stockholm University and the Karolinska Institute in Sweden to analyse data from the first South African National Health and Nutrition Examination Survey.

The purpose was to investigate how psychological distress and social position (using marital status, education, employment and income status as proxies) combine to influence the risk of malnutrition (overweight and underweight).

Calculating BMI

Using measurements of 6 424 people (aged 15 and older) who participated in SANHANES-1, the researchers calculated their body mass index (BMI) scores. BMI is a persons body mass (in kilograms) divided by the square of their body height (in metres). Health professionals use this value to broadly categorise a person as underweight (<18.5 kg/m2), having normal weight (18.5 to 24.9 kg/m2), overweight (25 to 29.9 kg/m2) or obese (≥30 kg/m2).

Using a questionnaire, trained fieldworkers also conducted interviews to learn more about the participantssocial positions.

Results a gender difference

Among women, the prevalence of obesity was 40.1%, almost four times higher than in men. Being married or in a partnership, educated, employed and having high income increased the risk of being overweight or obese for both genders.

Conversely, poor mental health was associated with an increased risk of being underweight in both genders. In this study, the prevalence of being underweight in men (11.9%) was almost three times that of women (4.2%).

The role of partnerships

In an attempt to explain some of these findings, the researchers looked at other studies and hypotheses. A study in Cape Town showed that cohabitation increases opportunities for sharing regular meals and overconsuming energy-dense foods due to social obligations; in South Africa, married women are expected to cook and dish up large food portion sizes, often with an abundance of red meat.

Many see a bigger body size as an indication of beauty and fertility in women, and prestige and happiness in both genders. An overweight married individual is often seen as well cared for by their spouse. However, in a 2012 literature review, it was suggested that married individuals may be less interested in body size maintenance as they are no longer looking to attract intimate partners.

Other studies have shown an association between reduced food consumption and being unmarried, getting divorced or losing your spouse. This may be due to changes in social support and social control, as well as stress and depression. In one such study widowers reported substantially higher rates of depression and poorer social functioning, while another study found that widowed individuals tended to enjoy food less.

The effect of ethnicity

Another interesting finding was the interaction between ethnicity and gender, suggesting that being non-African in South Africa increased the likelihood of being overweight and obese among men, but reduced this likelihood among women. More non-African men were overweight and obese than African men, whereas fewer non-African than African women were overweight and obese. These results are in line with results observed in the South Africa Demographic and Health Survey.

Explained by the social position proxies?

Surveys by Statistics South Africa show distinct education, employment and income disparities between men and women, and between African and non-African individuals. South African women, especially African women (30%), continue to be the largest group affected by unemployment, while 28% of African men are unemployed, compared with 21% of coloured, 12% of Indian/Asian and 8% of white men. Of those African men who are employed, the majority are employed in construction industries that require labour-intensive work during which they expend more energy, thereby controlling their weight. Conversely, many women who are employed spend most of their time around food as domestic workers and as workers in the food industry, where they expend less energy.

Education and income

According to the 2019 Quarterly Labour Force Survey, more than half (51%) of African youth aged 18 to 24 years have limited access to higher education institutions, often due to financial constraints. Many of them end up in non-permanent or part-time employment in the construction, mining and agricultural industries. According to the South African Living Conditions Survey, 84.6% of white, 20.9% of coloured and 46.9% of Indian/Asian households fall within the highest social position quintile, compared with only 11.1% of African households.

Men, non-Africans, and those living in male-headed households enjoy a better social position compared with their female and African counterparts. It is therefore possible that differences in obesity and disease prevalence between genders and ethnic groups in South Africa may be attributed to social inequalities.

Limitations of the study include difficulty of quantifying monthly income and the fact that the role of communicable conditions like HIV/AIDS and genetics could not be included in the analysis.

Consumption and inactivity

In a 2005 paper, researchers warned that the overconsumption of food high in simple sugars and saturated fats may cause glucose and lipid toxicity respectively. These conditions are associated with insulin resistance, which fuels type-2 diabetes and cardiovascular diseases.

Research shows that only 42% of South African women have been found to be physically fit, compared with almost two-thirds of men (62.4%). A small-scale study in 2014 involving African women showed that those women who were physically active tended to weigh less, have less overall body fat accumulation, have higher concentrations of serum high-density lipoprotein cholesterol (so-called good cholesterol), and were more insulin-sensitive compared with their less physically active counterparts.

Furthermore, by being overweight during pregnancy and overfeeding their babies, many women inadvertently perpetuate the cycle as these factors place their offspring at risk of obesity later in their lives.

Policy implication

These findings have public health implications for South Africa. Action is needed to combat malnutrition, which causes unhealthy weight among socioeconomically disadvantaged groups in the country, especially Africans. A generally high prevalence of obesity among women and the positive association of education, employment and income with being overweight and obese call for more investment in health literacy.


Dr Whadi-ah Parker