The truth about obesogens: can dust and chemicals make you fat?

With 26% of adults classified as obese in the UK in 2016, the hunt for causes and solutions to expanding waistlines is on. While public health messages have focused largely on the food we eat, some scientists suspect there is another factor at play: substances being dubbed as “obesogens” – found in our packaging, household goods and furnishings that might affect our hormones and the buildup of fat in the body.

However, experts are sceptical, particularly in the light of one report this week. It has made the bold claim that “removing shoes when entering the house and swapping carpet for wooden floors could help people stay slim”, citing a talk by researchers at the universities of Aveiro and Beira Interior in Portugal, who have suggested that preventing obesogens accumulating in the house by frequently sweeping and dusting could stop us gaining weight.

As Prof Russell Viner, president of the Royal College of Paediatrics and Child Health, says: “For some medical reasons, such as protection against allergies, yes, it’s advised to keep a dust-free home and so, too, is removing shoes to avoid bringing in dirt from outside, but these things will not make you a healthy weight. Only a balanced diet and regular exercise will do that.”

It is not the first study to moot the idea of the existence of obesogens. Earlier this year, researchers at Harvard University suggested compounds called perfluoroalkyl substances (PFAS) – widely used in products such as stain repellents and known to have a number of negative effects on human health – might lead to weight gain.

Others have voiced concerns that it isn’t even clear whether the level of supposed obesogens in house dust would be enough to affect the body anyway. “I think this is one of the cases where the researcher’s statement that “further studies are needed” is particularly important,” says Kevin McConway, emeritus professor of applied statistics at the Open University, who points out that while some of these chemicals have been shown to enter our diet, it’s not yet clear if they contribute to obesity in humans and to what degree – even if effects are found in some animals.

Prof Richard Sharpe, a scientist at the Centre for Reproductive Biology at the Queen’s Medical Research Institute in Edinburgh, has previously looked into the issue. “While it’s not possible to dismiss the hypothesis that certain environmental chemicals to which we are exposed could perturb [or] reset body regulatory systems so as to predispose to obesity, I remain unconvinced that obesogens are likely to be important players in the obesity epidemic,” he says. One reason, according to Sharpe, is that fast food and packaged foods, which are high in fat, also increase exposure to many of the chemicals suggested to be obesogens.

But, he adds, other factors are more likely to be behind the rise in obesity. “We have very detailed evidence from innumerable studies, including dietary intervention studies, that show unequivocally that our change of diet – increased fat/sugar/calorie consumption – and lifestyle – less exercise – in recent decades has caused the obesity crisis,” he adds. “Ultimately, no matter how obesogens or anything else might reset energy regulatory systems, you cannot get fat unless you consume the calories.”