A very simple question, but one that requires a detailed scientific answer, unfortunately!
Recently, one or two web sites have started to ask this question, or even state it as an unassailable fact. At first glance, the claim seems ridiculous, but there is a sort of strange logic behind it, albeit based on misinformation. The logic is based on the erroneous claim that parabens mimic oestrogen. Oestrogen is related to increased body fat (one of the reasons why women tend to have more body fat than men – at least, in different places!). The problem with this train of logic is that parabens do not mimic oestrogen, despite what many anti-chemicals organistions and commentators may claim.
The main source of this information was a study by Routledge in 1998 (Routledge, E.J, Parker, J, Odum, J, Ashby, J and Sumpter, J.P. Tox. & Appl. Pharm. 153, 12 – 19) which measured the oestrogenic activity of several of the parabens, both in vitro and in vivo – the in vivo results are the more relevant, because they better reflect “life”.( In vitro means “in glass”; “in vivo” means “in life”.)
This study found that butylparaben had oestrogenic activity 100,000 times weaker than the natural oestrogen tested alongside for comparison. The same study also found that methylparaben had NO oestrogenic activity. (if you check for information on Skin Deep, the Environmental Working Group’s cosmetics database, you will see that they have quoted this Information incorrectly). The terminology here is confusing, because “oestrogenic activity” does not mean that the substance behaves in the same way as oestrogen – it simply means that the substance can bind to the oestrogen receptors in the body; so oestrogenic activity does not automatically mean oestrogen mimickry. In fact, a further study carried out in 2006 (Pugazhendi, D, Sadler, A. J, Darbre, P. D, J. Appl. Toxicol, 27, 67 – 77) showed that the potential to mimic oestrogen (by measuring the effect on global gene expression – the REAL measure of oestrogen mimickry) was extremely low, because the researchers found that the parabens all behaved diffently – not only from each other – but also to oestrogen in their effect on global gene expression. Basically, it is of relatively little importance that substances can bind to oestrogen receptors ; what matters is the effect they have whilst they are bound, and parabens do not mimic oestrogen. – this 2006 study proves it.
Parabens do NOT mimic oestrogen, and nor is there any proven link to cancer, despite what you may read elsewhere.
So, the short answer to the question “do parabens make you fat” is “NO”!