It’s December, that time of year when we’re never more than a few days away from a Christmas party or an impossibly large feast. Such excesses of food invariably lead to the overeating, and subsequent weight gain, which inspires ill-fated News Years’ resolutions concerning tracksuits and fluorescent wristbands.
The World Health Organisation estimates that, in 2008, 35% of the world’s population was overweight. Brits are particularly guilty, with 24% of men and 26% of women in England found to be obese in a 2011 study. Such excessive weight can cause severe health problems, including Type 2 Diabetes, various cancers, and cardiovascular disease. Foods high in fat can also lead to elevated fat levels in the bloodstream, which increases the risk of heart attacks and strokes.
But research in the latest issue of Nature Communications has shown that these blood fat levels can be used to combat obesity. Researchers in Basel used synthetic biology to develop a genetic circuit that can be implanted into obese mice. This circuit involves the expression of pramlinitide, a clinically-licenced hormone, to supress appetite and promote satiation (fullness) in response to high blood fat levels. Obese mice fed on a high-fat diet showed a noticeable drop in body weight in response to the regulatory circuit. And because the expression is blood fat-dependent, normal-weight mice fed on a low-fat diet ate normally, without losing weight.
Martin Fussenegger, who led the research, believes that we may, one day, see his method being used as an alternative to liposuction and gastric bands in obese people. He said: “The advantage of our implant would be that it can be used without such invasive interventions.” But Sir Stephen O’Rahilly, professor of clinical biochemistry and medicine at the University of Cambridge, says that many hurdles will need to be overcome before this can happen: “Firstly, the hormone they used is only modestly effective for weight loss in humans – much less so than in mice – so it’s not at all clear that it would cause significant weight loss.
“Secondly, one would have to find a way of safely encapsulating cells and keeping them alive in a compartment in the human body in a manner that allowed them to function for long periods of time. If these are foreign cells, they will be prone to rejection. If they are cells from the patient themselves, then it could be prohibitively expensive to have to engineer a bespoke cell population for each patient.”
So as things stand, the easiest way to keep off unwanted podge for the moment is to refuse that third helping of Christmas pudding.