02 Feb Are we programmed to be fat? Chemical Obesogens
Overweight has become synonomous with living in the 21st Century – but what if there was more to addressing weight than just lifestyle and diet?
Obesity has increased substantially in western countries and developing countries in the past several decades, however this has simultaneously occurred in laboratory animals, infants and pets – trends that cannot be explained by diet and exercise alone. More than 50% of Australians are overweight or obese (ABS, 2008) which is similar to statistics in other western countries. Diet and lifestyle however does not sufficiently explain the 70% increase in infant obesity in the past 20 years. Fat tissue acts as an endocrine organ – releasing hormones (leptin) related to appetite, satiety and metabolism. There is a growing body of evidence linking chemical obesogens to obesity.
Obesogens are chemicals that inappropriately stimulate adipogensis (fat production) and storage. The effects of early life exposure is suspected to be irreversible
(Professor Blumberg from the University of California, 2011)
History
The accidental discovery was made by several scientists investigating the impact of hormone disrupting chemicals commonly found in foods, pesticides and household products, only to discover they were causing an epidemic of fat laboratory animals. Of greatest concern, is the fact that exposure to these chemicals early on in life (in the womb and early infancy) may trigger obesity in adulthood irrespective of the person’s diet or lifestyle. Professor Bruce Blumberg (University of California) was the first scientist to coin the phrase ‘obesogen’ in 2006. However the first reference to low dose chemicals causing weight gain was cited in a 2002 paper in the Journal of Alternative Complementary Medicine by Paula Baillie-Hamilton who suggested this has been occuring since the 1970s. In the past five years, there has been an increased number of animal and human studies on this topic.
Mode of Action
Obesogens program us to be fatter by altering our metabolic set point which is achieved by either increasing the number of fat cells, their size, enhancing insulin resistance or affecting our appetite. Most obesogens are endocrine disrupters that mimic or antagonise the actions of naturally occurring oestrogens. They act at very low doses in ppb and ppt (which is similar to one teaspoon in an Olympic swimming pool). As such, it is the timing and duration of exposure not the dose that makes these chemicals so harmful to a growing foetus and child during critical windows of development. In fact, the lower the dose, the greater the response by the body. In contrast the higher the exposure, the lesser the response as a result of ‘receptor down regulation’. These chemicals may:
- Increase the number and/or size of fat cells. For example, whilst BPA reduces the number of fat cells, it increases their size
- Influence hormones that affect appetite and satiety
- Epigenetics – pass on the effects of obesogens to later generations
The way in which our authorities regulate exposure to hormone disrupting chemicals in everyday products like BPA in our food tins and PFOA in nonstick cookware is not adequate. Like any hormone, the body is programmed to react to minute levels – levels that are typically found in everyday products. Ironically at high levels of exposure, the hormone receptors in our body shut down altogether through a process known as receptor downregulation. It is vital therefore that authorities act quickly to ban these chemicals from everyday products.
Hormone disrupting chemicals exert their effect at levels far below what is considered to be harmful. It is the timing and duration of exposure and NOT the dose that determines what impact these chemicals have on the body. Setting an acceptable limit of these chemicals in everyday products is not good enough in light of the fact that the body responds to minute amounts of these chemicals in the same way as it does to other hormones.
Health effects
- Infertility, Early puberty, Reduced sperm count
- Obesity, diabetes, metabolic syndrome
- ADHD
- Cardiovascular disease
- Parkinsons, autism…
Sources of chemical obesogens in your home
- Personal care and cleaning products – may contain phthalates (in fragrances), butylparaben (preservative) and nonylphenol (non ionic surfactants)
- Pesticides – atrazine, organochlorine pesticides such as DDT (still breaking down in our soils) and tributyltin (TBT) used as a wood preservative
- Perfume – may contain phthalates and synthetic musks which mimic the effect of oestrogen in the body
- Polyvinyl chloride (PVC) – in our plumbing, shower curtains, carpets, furnishings and building materials
- Bisphenol-A (BPA) – cash register receipts, carbonless paper, epoxy resin lining our food tins, polycarbonate plastics (drinking water bottles, some baby bottles…),
- Perflurooctanoic acid (PFOA) – in non stick cookware, water proof clothing (Goretex), Scotchgard stain repellent (carpets, mattresses, furnishings, microwave food items…)
- Food packaging – microwaveable food items,
Stay tuned – we are going to hear alot about this. Watch the trailer for the new documentary: Programmed to be Fat? by David Suzuki and Dreamfilm Productions.