NEB English Grade 11: You May Scoff … (Health and Exercise)

text courtesy: www.newscientist.com

Read the following article about staying slim:

Who needs diets and exercise? There are plenty of other ways to stay slim.

The holidays are a time of excess. Eat, drink and be merry, for tomorrow we diet or perhaps not! Unfortunately, we do not all have the self-discipline and determination; it takes to cut back on cake and hit the gym. But fear not – there could be other ways to shift the fat and stay trim

Just to get this straight, if you over-eat and under exercise you will gain weight. However, growing evidence suggests that other factors also contribute to excess adiposity. Last year, David Allison at the University of Alabama in Birmingham, Ala., highlighted this when he discovered that humans are not alone in piling on the pounds. He looked at wild animals, lab animals; even animals kept on the same highly controlled diets for decades, and found that all were becoming heavier (Proceedings of the Royal Society B, vol. 279, p. 1626). Allison concludes that whatever factors are fattening up the animals that live around us might also help explain the human obesity epidemic.

That being the case, identifying these alternative factors should give us new ways to fight the bulge. The good news is that researchers worldwide are beginning to do just that. It is not yet known how much each factor contributes to obesity, but we can nevertheless suggest ways of avoiding them – and some are far less painful than dieting or pounding the tarmac.

Get vaccinated

If you catch a cold this holiday season, you may have to stock up on new clothes as well as tissues. That’s because at least one common cold virus has been linked to obesity. Nikhil Dhurandhar of the Pennington Biomedical Research Centre in Louisiana discovered that adenovirus-36 (AD-36) boosts both the number of fat cells in the body and the amount of fat inside these cells. He also found that obese people are nearly three times as likely as those of healthy weight to test positive for AD-36 antibodies, indicating current or past infection (Obesity, vol. 14, p. 1905). Another study reported that children with AD-36 antibodies weighed an average of 23 kilograms more than children without them (Paediatrics, vol. 126, p. 721).

The “fat effect “of AD-36 might persist for several years in humans, although nobody knows for sure. Meanwhile, another 10 microbes have been reported to make animals fatter. While it sounds alarming, this could actually be good news in the fight against flab. “If indeed some infections contribute to obesity in people, we could have a potentially very simple and effective prevention strategy – vaccination, “says Dhurandhar.

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Chill!

While extreme stress tends to make people lose weight, the everyday kind can have the opposite effect. So, for the sake of your waistline, take a deep breath, and don’t let the festive family bickering get to you.

Failing that, try giving the new-year diet a miss. One recent study found that moderate calorie restriction made mice much more sensitive to stress, and this effect persisted once the diet was over. The mice went on to choose more high-fat food than those that had never had their food restricted (Journal of Neuroscience, vol. 30, p. 16399)

Brain imaging studies by Rajita Sinha, director of the Yale Stress Centre at Yale University showed that stress increases activity in the ventral striatum, a region associated with reward and habits (Neuro psychopharmacology, vol. 36, p. 627). “So it increases craving for high calorie foods in those who have a habit of consuming them,” she says. Instead of counting calories, she recommends mindfulness, stress reduction and meditation techniques to cultivate an awareness of how your thoughts and behaviour can undermine your health. “They can help with taking control over the urges and stress-related eating of high-calorie food”.  Everybody say “om”.

Chill some more

Over the past three decades, homes in the US and UK have become warmer. Fiona Johnson at University College London and colleagues think this may be making us fatter (Obesity Review, vol. 12, p.543). Simona Bo of the University of Turin, Italy, agrees. In a study of more than 1500 middle-aged adults, her team found that those whose home temperatures ranked in the top third were about twice as likely to become obese over the six-year period of the research (International Journal of Obesity, vol. 35, p.1442).

Shivering obviously burns energy, but you don’t need to be freezing for your body to chew through extra calories. Most fat on our bodies is a type called white fat. But when temperatures get down to about 18°C, brown fat – which is abundant in babies and which adults mostly carry around their necks – starts burning energy to warm you up.

Unfortunately, if you were not regularly exposed to cold, your brown fat deposits shrink and so too does your capacity to burn off that extra holiday treat. Any change will help, though, says Johnson. You burn steadily less energy as environmental temperatures rise from 15°C to 28°C. “So turning down the thermostat by any amount is likely to have some small effect,” she says. Do try this at home.

Watch the packaging

As well as looking at the nutritional labeling, you might also want to watch the actual material your food comes wrapped in. Some plastic packaging and cans contain endocrine disrupter chemicals that can leach into food and drinks, and evidence is starting to link some of these to expanding waistlines.

Endocrine disrupters change the normal functioning of hormones. Many interfere with the functioning of the thyroid, which produces hormones that regulate metabolic rate. One group, known as phthalates, also seems to activate a receptor in the cell nucleus called PPAR (peroxisome proliferator activated receptor)-gamma, involved in storing fat and metabolizing glucose. In 2010, a team led by Elizabeth Hatch at Boston University reported that men with a bigger body mass index (BMI) and waist circumference had higher blood concentrations of metabolites of phthalate (International Journal of Andrology, vol. 33, p.324). Other research has linked obesity to exposure to bisphenol A, which is another endocrine disrupter.

Debate continues over whether these chemicals are harmful or not, and avoiding them is tricky. But look out for PVC packaging – labeled “Type 3” for recycling purpose – which can contain phthalates or bisphenol A. And be especially wary when buying fatty foods in which endocrine disrupters tend to accumulate, posing a potential double threat.

Turn down the lights

If your idea of a holiday workout is lifting glasses of beer late into the night, then it’s not just the extra calories you need to worry about. Randy Nelson and his team at Ohio State University in Columbus found that mice exposed to light at night weighed 10 per cent more at the end of the eight-week study than mice that had experienced a standard light/dark cycle, even though they ate the same total number of calories and did the same amount of exercise (Proceedings of the National Academy of Sciences, vol. 107, p.18664). Several other studies have found that shift work makes people fatter.

Light at night might alter circadian clock genes, changing an individual’s metabolism, Nelson suggests, “It’s difficult to specify an appropriate light cycle for everyone,” he adds. But he recommends keeping a consistent pattern throughout the week and, if possible, avoiding blue wavelengths of light at night (New Scientist, 7 May, p.44). Produced by many LED bulbs, these are known to be especially disruptive to the circadian system.

Move to the country

A brisk walk or jog outdoors can only help in the battle against the bulge, unless you are doing it in a busy city. Breathing polluted air can cause extra fat to accumulate around your stomach and also make your cells less sensitive to insulin, increasing your risk of developing type 2 diabetes. “We believe that air pollution plays a very important role in the current obesity epidemic,” says Xiaohua Xu of Ohio State University.

Xu exposed young mice to air heavily polluted with fine particles for 6 hours a day, five days a week, and found that after 10 weeks they had about 50 per cent more abdominal fat than mice that were fed the same diet but inhaled filtered air. The fatter mice also had elevated blood levels of a protein involved in inflammation called tumour necrosis factor-alpha. Xu believes this may help explain the changes to their fat cells, as well as their deceased sensitivity to insulin.

Another study found a strong link between levels of fine particulate air pollution and the prevalence of type 2 diabetes in North Americans (Diabetes Care, vol. 33, p.2196). “We were shocked that the association held up as well as it did,” says John Pearson at Harvard University, who led the research. Fine particles can blow around the globe so you can never entirely escape them, even if you can afford to move out of the city. But if you have a choice, it still might be worth picking a rural ramble over an urban jog.

Have a lie-in

If you need an excuse for spending more time in bed during the holidays, this could be it: too little sleep can make you fat. Simona Bo of the University of Turin, Italy, found that the adults who became obese during her six-year study slept an average of about 6.3 hours a night, compared with about 7.2 hours for those who maintained a healthier body weight. The link between sleep and weight held even when her team took into account other important causes of obesity, such as low level of physical activity. Rachael Taylor at the University of Otago, New Zealand, has found that children aged between 3 and 5 who sleep less than the average of 11 hours a night are also more likely to be overweight or obese by the time they are 7 years old. (BMJ, vol. 342, p. 2712)

Sleep deprivation reduces the secretion of leptin, a hormone that suppresses appetite, and increases levels of ghrelin, a hormone that stimulates appetite. “Or it could be as simple as less sleep means more time to eat”, says Taylor. Either way, an extra hour in bed sure beats going to the gym.

Emma Young

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