London - When it comes to losing weight, most of us are aware of the three factors at play: genetics, the number of calories we consume and the energy we are prepared to expend sweating our way into shape.
We can’t choose our parents but, according to the dieting mantra, eat healthily, exercise regularly and the pounds will eventually drop off.
But what if your body stubbornly refuses to remove excess fat, despite concerted efforts to shift it?
Emerging evidence suggests that a more sinister reason than food and activity could be contributing to weight problems and that so-called “chemical calories” lurking in everyday beauty products such as shampoo, body lotions and soap could be to blame.
Doctors at the Mount Sinai Medical Centre in New York claim that phthalates, chemical ingredients in 70 percent of cosmetics as well as many household cleaning products, have been shown to throw the body’s natural weight control system, a delicate balance of hormones, off kilter.
They suggest that exposure to phthalates through daily use may be linked to childhood obesity and weight problems in adults.
In their long-term study on girls living in the inner city area of East Harlem, the Mount Sinai team measured exposure to phthalates by analysing the children’s urine.
“The heaviest girls have the highest levels of phthalates in their urine,” says Professor Philip Landrigan, a paediatrician and the study author. “It goes up as the children get heavier, but it’s most evident in the heaviest kids.”
Phthalates have been widely used as gelling agents in cosmetics, cleaning products and to make plastic bottles for more than half a century, but it has only just come to light that there may be possible health risks.
Another substance, Bisphenol-A (BPA), also present in containers and bottles, has also been found to provide “chemical calories”.
It’s the fact they are absorbed into the body that causes most concern. Billed as “endocrine disruptors”, they are known to affect the glands and hormones that regulate numerous bodily functions.
Studies on animals have shown consistently that the chemicals depress testosterone levels, known to be a risk factor for weight gain. They have also been found to mimic the effects of oestrogen, which have been linked to weight gain and early puberty.
Further research on humans linked phthalates with poor semen quality in men and with subtle alterations in the reproductive organs of male babies. And now come the latest revelations that they may also influence weight.
In numerous studies, mice exposed to such “endocrine disruptors” became obese. But could the same effect occur in people?
Zoe Harcombe, nutritionist and author of the Obesity Epidemic, says that even the slightest disruption to hormone levels “is very bad news” for someone trying to lose weight.
“In men, phthalates and other chemicals have an anti-testosterone capacity that has been linked to obesity,” she says. “In women they mess up our basic genetic hormone balance so that you get disruptions similar to those that might occur during the menopause or at puberty.”
Using phthalate-containing cosmetics when you are dieting could make matters worse. “Women who follow a low-fat diet are likely to suffer the most from adverse side-effects to these chemicals,” says Harcombe:
“By reducing the fat they consume, they also reduce the fat-soluble vitamins in their body. That often leaves them with dry skin. They slather on moisturisers to rectify that problem without realising they are unwittingly causing another by supplying chemical calories through the skin.”
Among those at the forefront of tackling obesity, the influence of chemicals is a hot topic. Tam Fry, a spokesperson for the National Obesity Forum, says many obesity doctors accept that the hormonal disruption caused by exposure to chemicals does play a part in weight problems. While under-activity and over-eating remain the major causes of obesity, Fry says more work needs to be done to confirm the links.
“There is particular concern about whether these chemicals with an oestrogenic effect are contributing to earlier puberty in girls,” Fry says. “Girls reach puberty when they are at a weight that can support the reproductive cycle and this is getting earlier and earlier. Whether that’s a result of straightforward over-eating by a generation of young girls or whether there is an additional chemical effect, we don’t yet know.”
It’s not just girls who seem susceptible to the phthalate effect. In 2007, researchers at the University of Rochester school of medicine in New York found the same class of chemicals were contributing to abdominal obesity and insulin resistance, a precursor to diabetes, in men.
The Rochester scientists analysed the urine, blood samples and other data of 1,451 men. They found that those with the highest level of phthalates in their urine had more belly fat and insulin resistance and suggested that depressed testosterone levels due to chemicals was the underlying cause of their weight gain.
Dr Paula Baillie-Hamilton, author of Stop the 21st Century Killing You and a researcher on human metabolism who has studied the connection between chemicals and obesity at the University of Stirling, is convinced that the abundance of chemical calories in our lives is the reason why so many people are getting fatter despite dieting and exercising more.
“It’s a theory that was poo-pooed a decade ago but which has become a new field of medicine in itself,” says Dr Baillie-Hamilton.
But how easy are chemical calories to avoid?
Paediatrician Professor Landrigan concedes that you can’t avoid them completely, but can reduce your exposure by checking labels for phthalates and bisphenol-A. “Eating as much organic food as you can will reduce your chemical intake, but choosing cosmetics and toiletries carefully is also very important,” he says.
“If you put something on your skin, you absorb it and you need to find a brand that doesn’t use phthalates or any chemicals. The science against them is strong.” - Daily Mail