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Is obesity a ‘bigger killer than malnutrition’? It’s complicated

A popular Facebook page, Facts SA, made an interesting claim about nutrition. But on this one, its “facts” were a little bloated.

  • “Malnutrition” is often used to mean having too little food, but obesity – a complex diagnosis where excessive body fat impacts health – is also considered a form of malnutrition.

  • Obesity is often indicated by a high body-mass index (BMI). While BMI does not measure body fat directly and obesity should be diagnosed by a medical professional, the index is widely used to estimate its prevalence. 

  • High BMI is a risk factor in a number of diseases, and these cause more deaths globally than a deficiency of nutrients from eating too little.

“Obesity is now a bigger killer than malnutrition” claims a recent Facebook post in FACTS SA, a South African page with more than 187,000 followers.

But is this true? To find out, we need to unpack what researchers mean when they talk about concepts like obesity and malnutrition.

What is malnutrition? 

According to the World Health Organization, malnutrition is a blanket term that can refer to “deficiencies or excesses in nutrient intake, imbalance of essential nutrients or impaired nutrient utilization”.

Generally when we think of malnutrition, we associate it with having too little food or being underweight. But obesity is also considered a form of malnutrition. Not having enough food is usually referred to as protein-energy malnutrition (PEM) in medical research and is a lack of protein or energy caused by not eating enough. 

What is obesity? 

To better understand how scientists define obesity, Africa Check previously spoke with Rachel Jackson Leach, deputy director of research and evidence at the UK-based World Obesity Federation. She said obesity could be defined as “a complex, relapsing, multifactorial disease, characterised by abnormal or excessive body fat that impairs health”.

Researchers have explained that obesity is often considered a type of malnutrition because “despite excessive energy consumption [obesity] is associated with a shortage of individual microelements”. 

Although obesity is commonly associated with high-calorie diets, people with body weight in the obese range often lack particular important nutrients.

How many people die as a result of obesity and malnutrition?

If obesity is a subcategory of malnutrition, it doesn’t make sense to say that more people die from obesity than from malnutrition. Malnutrition-related deaths would include obesity-related deaths, as well as deaths from other forms of malnutrition. 

Whether someone is obese is usually determined using the body mass index (BMI), a ratio between your height and your weight. You can calculate your BMI here.

But BMI does not measure body fat directly and obesity is not as simple as having high body fat. Leach told Africa Check someone who had a high BMI should see a healthcare professional to determine whether they were obese. 

Even though BMI is not a perfect way to diagnose obesity, it is often the best screening tool available and is therefore considered an efficient way to estimate prevalence rates. 

Obesity considered a risk factor, not direct cause of death

Looking at obesity and malnutrition as causes of death is also complicated. To learn more, Africa Check spoke to Salome Kruger, professor of nutrition at South Africa’s North-West University

Kruger explained that rather than being a direct cause of death, obesity increased the risk of developing other diseases, such as “cardiovascular diseases and type 2 diabetes, and complications of these”. 

Researchers therefore often measure “deaths attributable to obesity” or “overweight” where a person died from a disease where having a high BMI score was a risk factor. 

According to the Global Burden of Disease (GBD) study, a major study on the causes and risk factors for death and disease last published in 2020, high BMI was a risk factor in just over 5 million deaths in 20`19. 

In South Africa, the estimated number of deaths in which high BMI was attributed as a risk factor was around 55,000 in 2019. 

Fewer people globally die of protein-energy malnutrition

Globally around 212,000 deaths in 2019 were attributable to protein-energy malnutrition (PEM), according to GBD data, which may be the type of malnutrition the Facebook post means to refer to. In South Africa in the same year just over 2,000 people died from PEM . 

If we are comparing PEM and obesity, then obesity is a risk factor in more deaths than the number of deaths caused by PEM. But it is not accurate to say that obesity is responsible for more deaths than malnutrition, because obesity itself is a form of malnutrition.

Overweight and obesity: Not simply a result of personal choice

High body weight is often associated with excessive food consumption. But evidence suggests that weight is determined by complex interactions between a person’s genetics, environment and society. Overweight and obesity aren’t simply a result of personal choice but this perception can increase the stigma and discrimination faced by people who are classified as overweight or obese. You can learn more about weight-related stigma and discrimination here.

Further Reading

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