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 kilos will eventually drop off. But what if your body stubbornly refuses to remove excess fat despite concerted efforts? 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 Center in New York claim phthalates, chemical ingredients in 70 per cent 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 after absorption through skin. Article continues below They suggest that exposure to phthalates through daily use may be linked to childhood obesity and weight problems in adults. Another substance, Bisphenol-A, also present in containers and bottles, has also been found to provide \"chemical calories\".