From VOA Learning English,this is the Health and Lifestyle report.For the past 15 years,experts on obesity have gathered in Plymouth, Englandto attend a conference.It is estimated that more than half the city's adultsare overweight or obese.The rest of Britain is not doing much better.But what is happening in the U.K.is also happening in the U.S.and other Western countriesas well as in a growing number of developing nations.VOA's Joe De Capuatalked with the expert who chaired the conferencecalled the Plymouth Symposium on Obesity,Diabetes and Metabolic Syndrome.Jonathan Pinkney is a professor of endocrinologyand diabetes at Plymouth University.Professor Pinkney said obesity is a long-term problemthat is very difficult to solve.He said no one health issuehas more impact on human health than obesity.Professor Pinkney called obesity a complex issueinvolving more than what a person eats."I personally feel that this is such a wide field.There are so many issues. There's politics. There's biology. There's the food industry.There's everything you can imagine.So, I think it's right to talk about everything under one umbrella.Mr. Pinkney says obesity can interfereand impair the ability to have a normal life.It can destroy or devastate personal relationship."When body size becomes so huge that it impairs people's day-to-day functionand quality of life and well-being and personal relationships... yeah, that's kind of devastating.That tends to occur at a higher level of body weight."Mr. Pinkney warns that even people who are not considered obesecan still be at risk.He said many people eat the wrong foodsand do not get enough physical activity.People have been getting heavier and heavier slowly over time, he said.And that's a problem."That's the more important point for the health of the population.You know, all the diabetes and heart attacks and cancers and things.I mean that's really caused by lower levels of weight gain."The conference provided much information about the biology of the brainand appetite control.The professor said people know how to eat healthy.But this knowledge is often overtaken by marketing of the food industry.Advertisers show food on television and in print in a way that creates immediate desire.Professor Pinkney said these images can help lead some people to eat unhealthy foods.He said he believes such pressure overpowers the biological systemsthat work to keep people at a healthy weight.Professor Pinkney said it is difficult to make progress in populationsthat eat a lot of sugar, salt and fat."There's a multinational food industry and there's huge vested interest in selling a lot of the stuff."The expert argued that the obesity epidemic must be stopped at its source:when eating habits begin. Children, he said,often learn poor eating habits from their parents."I think a lot of things start very early in life.You know, it's difficult to break the habits of a lifetime, isn't it? I think we all find that.But I think our health and our prospects for the futureare kind of laid down fairly early.And I think that's not surprising. Big kids often have big parents.I think they learn this at an early stage."The professor suggests one way to improve the situation.He said children should be protected from advertising and marketing put out by the food industry.Besides marketing campaigns,the professor also blames refined carbohydrates and sugarsfor much of the obesity epidemic.Carbohydrates are commonly put into two groups:simple and complex.They can also be categorized as unrefined and refined carbohydrates."Refining" is a process that removes fiber,nutrients and other items contained within the food in its natural state.Refining also concentrates sugarsand can cause our blood sugar levels to change more rapidly than normal.This can cause people to feel tired or put them in a bad mood.It can also increase the appetite.Prof. Pinkney said these refined, overly-processed foods set people up to fail.Without complex fiber,these foods do not satisfy a person's hunger for long.So, people eat their next meal sooner than normal.Prof. Pinkney suggests we learn from our distant ancient ancestors -- the hunter-gatherers."The hunter-gatherers, you know, going right back tolast Ice Age and before thatwould have had a diet that was rich in complex, sort of, fiber type carbohydrate.There would be protein in it now and again.But it didn't have all the sugar.So, the diet that is, of course, followed by traditional peoples is radically different."Prof. Pinkney said all these areas– from advertising and policy to medical interventions– need to be addressed to stop the obesity epidemic.The U.S. Centers for Disease Control and Prevention says over 35 percent of American adults are obese.That is almost 79 million people.The government agency says more than 17 million children are obese.The yearly medical cost of obesity in the U.S. is almost $200 billion.Words in This Storysymposium – n. a formal meeting at which experts discuss a particular topicendocrinology – n. a branch of medicine concerned with the structure, function and disorders of the endocrine glandsdevastate – v. to destroy much or most of (something) : to cause great damage or harm to (something) ; devastating is the adjective.under one umbrella – idiomatic expression to be in one placeappetite – n. a physical desire for foodhabit – n. a usual way of behaving; something that a person does often in a regular and repeated wayintervene – v. to become involved in something (such as a conflict) in order to have an influence on what happens intervention is the noun