Extra Weight Gain Through Yo-yo Dieting

Researchers from the EU-funded EVOMECH project have warned that repeated dieting may lead to weight gain as the brain interprets the diets as short famines and urges the person to store more fat for future shortages.

cancer, Huntington, man flu, black hole, Carbon dioxide, genes, Alzheimer, Brain-computer interfaces, graphene, immune system, topology, climate change, Twin Embryos, blue brain, climate change, human genome, mature B cell neoplasia, artificial iris, autonomous robot, chemotherapy, tidal energy, Nanomedicine, ecosystem, Mycotoxins, obesity, methylisation, deep drilling, brain scans, volcanic gas, biocatalyst enzymes, earthquakes, detectors, robotics, asthma sufferers, infrastructure, olive trees, solar energy, satellites, olive oil, robotic arms, zika virus, locked-in state, digital detox, climate change, climate, stroke, The new production method was developed by engineers at the University of Exeter. It consists in creating entire device arrays directly on the copper substrates used for the commercial production of graphene, after which complete and fully-functional devices can be transferred to a substrate of choice. This process has been demonstrated by producing a flexible and completely transparent graphene oxide-based humidity sensor. Not only does this device outperform currently-available commercial sensors, but it’s also cheap and easy to produce using common wafer-scale or roll-to-roll manufacturing techniques. ‘The conventional way of producing devices using graphene can be time-consuming, intricate and expensive and involves many process steps including graphene growth, film transfer, lithographic patterning and metal contact deposition,’ explains Prof David Wright from Exeter's Engineering department. ‘Our new approach is much simpler and has the very real potential to open up the use of cheap-to-produce graphene devices for a host of important applications from gas and bio-medical sensors to touch-screen displays.’ One of team’s main objectives was to increase the range of surfaces that graphene devices can be put on. Whilst the demonstrated humidity sensor was integrated in a plasdinosaur, dieting, coral, dengue epidemics, vaccines, thermal energy, artificial intelligence, Cloudlightning, Memristors, Sensory Tool, HIV, autonomous robot, offshore renewable energy, Wearable robots, processors, Artificial, climate, plasmons, Antarctica’s ice, cryogenic preservation

‘Tis the season to be jolly and as the festive period gets well under way, many people will be consuming larger amounts of food and alcohol over the coming weeks. As a result, they’re probably already considering the almost-mandatory January detox and diet regime, possibly even being the New Year’s resolution for 2017. In fact, losing weight and staying fit and healthy are consistently the top two New Year’s resolutions as reported by US firm Nielson.

However, researchers from the universities of Exeter and Bristol, as part of the EU-funded EVOMECH (The evolution of mechanisms that control behaviour) project have warned against one particular type of intense dieting that they argue can actually cause additional weight gain. They found in a study recently published in the journal ‘Evolution, Medicine and Public Health’ that people who engage in ‘yo-yo’ dieting – a vicious cycle of weight gain and evermore severe dieting to combat such weight gain – triggers a survival mechanism hard-wired by evolution that causes the brain to interpret repeated diets as periods of food scarcity. As a result, when a person is not actively dieting, the brain urges the body to eat more and store more fat.

They explain that animals respond to the risk of food shortage by gaining weight, which is why garden birds, including the very seasonal red robin, are much plumper in the winter, when seeds and insects are much harder to find.

The scientists constructed a mathematical model to investigate the phenomenon in a simulated animal that does not know when to expect its next meal. It showed that during times of scarcity, an animal that grabs the opportunity to put on weight has the best chance of passing on its genes.

Consequently, the researchers’ model when applied to humans, who evolved in environments where reliable food sources were both sometimes plentiful and sometimes scarce, predicts that the urge to eat increases hugely as a diet goes on. Importantly, in an age where increasing obesity rates have become one of the biggest public health concerns in the West, this urge won’t diminish as weight is gained because the brain becomes more convinced that it will need to make preparations for a famine.

Dr Andrew Higginson, Senior Lecturer in psychology at the University of Exeter and one of the study authors commented: ‘Surprisingly, our model predicts that the average weight gain for dieters will actually be greater than those who never diet. This happens because non-dieters learn that the food supply is reliable so there is less need for the insurance of fat stores.’

‘Our simple model shows that weight gain does not mean that people’s physiology is malfunctioning or that they are being overwhelmed by unnaturally sweet tastes,’ added Professor John McNamara, of the University of Bristol‘s School of Mathematics. ‘The brain could be functioning perfectly, but uncertainty about the food supply triggers the evolved response to gain weight.’

So this then begs the question, what is the optimal way to lose weight? ‘The best thing for weight loss is to take it steady. Our work suggests that eating only slightly less than you should, all the time, and doing physical exercise is much more likely to help you reach a healthy weight than going on low-calorie diets,’ Dr Higginson advises.

Source: Based on information from CORDIS.