Updated 05 March 2013

SA obesity: are environmental toxins to blame?

An overload of environmental toxins in the body may hamper fat metabolism and weight control, a number of experts warn.

In an attempt to identify what besides excess food intake and lack of physical activity is driving the obesity epidemic in South Africa, we have in the past two weeks been considering many factors that can play important roles in weight gain or the inability to lose weight. While reading up on obesity in general, I came across a note in my nutrition handbook that asks the question: "What’s in that fat when you lose it?" by Sheila Dean (Mahan et al, 2011).

My literature search then led me to articles that propose that it is the "Toxic Environment" that is causing the global pandemic of obesity. The evidence emerging from recent studies is truly alarming.

We are surrounded by toxins

The above mentioned short article on "What’s in that fat when you lose it?" by Sheila Dean (Mahan et al, 2011), points out that we are increasingly being exposed to internal and external toxins.

External toxins are derived from the environment and may enter the body due to exposure to a staggering array of chemicals, pesticides, and herbicides that contaminate practically everything we come into contact with: the air we breathe, the water we drink and the food we eat. Internal toxins arise from the gut as breakdown products of our own metabolism.

Under normal, pre-modern circumstances, most people were capable of detoxifying their bodies thanks to so-called endogenous detoxification mechanisms. But in the modern world which more and more South Africans live in, our endogenous detoxification mechanisms are so overloaded that the excess toxins are stored in our fat depots.

When a person loses weight (fat), these stored toxins (e.g. bisphenol, DDT, etc) are released back into the body where they interfere with normal metabolism. It has even been suggested that the release of toxins during fat loss may be responsible for slowing down weight loss or, in some cases, stopping it altogether (Mahan et al, 2011). 

In view of this flood of toxins that we potentially release into our bodies when we lose weight, it is recommended that women should lose weight before they conceive to prevent potential damage to the foetal brain (Mahan et al, 2011).   

Effects of toxins

According to Sheila Dean (Mahan et al, 2011), toxins may change metabolism, disrupt the function of hormones, damage the mitochondria in our cells, increase inflammation and oxidative stress, lower the levels of the thyroid hormones we produce, and change our circadian rhythms and the autonomic nervous system, all of which can in turn hamper the most important weight control mechanisms in the human body.

According to researchers, writing in the Italian Journal of Paediatrics, “Recent accumulating evidence suggests that obesity may present an adverse health consequence of exposure during the critical developmental window to environmental chemicals disrupting endocrine function.” (Latini et al, 2010). The “critical developmental window” is the period from conception through foetal development in the mother’s womb until the end of the first two years of life. Infants and young children are probably the most vulnerable group when it comes to exposure to harmful chemicals and endocrine disrupters.

Bisphenol A is one of the environmental pollutants that has been implicated in the development of obesity and hyperlipidaemia (raised blood fat levels which are linked to heart disease). It also appears to affect the transport of glucose in fat cells and inhibits the release of an important adipokine (a compound which prevents development of the metabolic syndrome) (Latini et al, 2010).


Grün and Blumberg (2009) describe the many potentially obesogenic actions of a variety of chemicals that contaminate our environment. For example, the most important environmental sources of so-called ‘organotins’ which interfere with normal fat metabolism can be found in marine paints, wood catalysts, plasticisers, slime-preventing chemicals in industrial water systems and fungicides in foods. These authors believe that the major environmental sources of organotins are “contaminated seafood, agricultural products, drinking water and leaching from plastics”.


At the moment there are no general solutions to this problem. Faced with ever increasing contamination of our water supplies, foods and the atmosphere, South Africans and the entire global population seem to be helpless to stop this attack on our fat-regulation systems. Until more research is done to pinpoint the most dangerous chemicals and ways are found to reduce their presence in our water, food and air, the human race appears to be doomed to continue to gain weight.

For example, if we had to remove the hundreds of chemicals found in the water supply, water would become so expensive that most of us could not afford it. Many years ago I attended a congress dedicated to water purification. As delegates we were taken on a visit to a local water purification plant. The engineer in charge showed us the various processes that were then used to remove undesirable solid waste from the water and to disinfect it against the majority of pathogens. He then smilingly presented us with a glass of clear recycled water and asked who would like a drink! No one volunteered, so he downed the glass of water himself.

When I asked this same engineer what processes were available to remove chemicals and contaminants such as oestrogen derivatives from the water before it was recycled, he said that although such processes existed, they were prohibitively expensive as they required the water to be passed through resin columns. Such processes (reverse osmosis filtration,  nanofiltration or granular activated carbon filtration) (Kizer & Smolen, 2008), are probably even more expensive nowadays, so most South Africans will continue to be exposed to organotins and other obesogenic compounds. 

Let’s support actions to keep our precious water supply as clean as possible, because once a nation’s water supply becomes toxic, the food supply also becomes contaminated and toxic. With acid drainage from the mines, millions of women using hormones and collapsing waste purification systems in many municipalities, South Africans appear to be helpless to avoid the effects of obesogens in our environment.

- (Dr IV van Heerden, DietDoc, first published on 12 November 2012)

(Pic of danger sign from Shutterstock)

(References: Grün F, Blumberg B (2009). Endocrine disrupters as obesogens. Molecular & Cellular Endocrinology. Vol 304(1-2):19-29; Kizer MA, Smolen MD (2008). Treatment methods for removal of pharmaceuticals and hormones from drinking water. Oklahoma Cooperative Extension Service, BAE-1523.; Latini G, Gallo F, Iughetti L (2012). Toxic environment and obesity pandemic: Is there a relationship? Italian Journal of Pediatrics. Vol 36: 8; Mahan LK et al, 2011. Krause’s Food and the Nutrition Care Process. 13th Edition. Elsevier Saunders, USA)


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