Losing weight can be toxic for your health, and even lead to dementia and cancer, researchers from the Kyungpook National University, Daegu, have said.
Long-term weight loss can lead to the release of persistent organic pollutants (POPs) into the blood, which might in turn damage the internal organs of the body, they claimed.
POPs are man-made organic compounds used in the manufacture of drugs, and pesticides. They accumulate in human tissue and have been linked to a wide variety of illnesses, including disruption of the endocrine, reproductive and immune systems, dementia, and cancers.
The study results showed that concentrations of seven commonly occurring POPs were significantly higher in people who had lost weight over a ten-year period, and were lower in those who gained weight over this time.
However, some scientists disagree.
"Their evidence seems to suggest there's a possible association between weight loss and elevated POPs, but not necessarily that the weight loss is the cause of the raised POPs," said Professor Lesley Campbell at Sydney's Garvan Institute.
She did add that rapid loss of weight such as that in anorexia or cancer, is obviously harmful but "losing one kilogram a week as part of a diet and exercise program isn't going to be harmful, and shouldn't scare people off from trying to losing weight".
The scientists published their results in the International Journal of Obesity.