Fat or sugar: what's more irresistible?

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Is it the sweet flavor or the smooth and creamy texture that our taste buds are after? The New York Times has written about a new study that suggests that what really draws people to sweet treats, and prompts them to eat much more than they should, is not the fat, but the sugar.
By Olga Yazhgunovich: While doctors often warn against fattening sodas, snacks and fast foods, the role of sugar in influencing the brain has been somehow diminished. The new research led by Dr. Stice tracked brain activity in 106 healthy teenagers — 47 male and 59 female — they were asked to sip different milkshakes as they lay in functional magnetic resonance imaging machines. As they drank chocolate-flavored milkshakes that were identical in calories but either high in sugar and low in fat, both kinds of shakes lit up pleasure centers in their brain, but those that were high in sugar did it far more effectively, firing up a food-reward network that plays a role in compulsive eating. The researchers found that sugar was even a more powerful stimulus than fat. High sugar shakes that were low in fat ramped up the reward circuitry just as strongly as the more decadent shakes that paired sugar and fat in large quantities, suggesting that fat was a runner-up to sugar, said Eric Stice, the lead author of the study, which was funded by the National Institutes of Health and published in The American Journal of Clinical Nutrition. "We do a lot of work on the prevention of obesity, and what is really clear not only from this study but from the broader literature over all is that the more sugar you eat, the more you want to consume it," said Dr. Stice, a senior research scientist at the Oregon Research Institute. "As far as the ability to engage brain reward regions and drive compulsive intake, sugar seems to be doing a much better job than fat." The new findings add to a growing number of brain studies that are providing a more complex understanding of what drives people to overeat. Heavily processed foods loaded with fat and sugar activate and potentially alter the same reward regions in the brain that are affected by alcohol and drugs. Thus, the results may help explain why millions of people who diet and struggle to lose weight ultimately fail. Sugar itself isn't inherently evil as our body uses sugar to survive, and burns it to generate the energy necessary for life. Many healthy foods are actually broken down to sugar and glucose is a great energy source for the body. However, there are ways that sugar can do harm and cause fat storage. Excess glucose is the first problem – anytime when we fill the body with more fuel than it actually needs (which is easy when eating foods with high sugar content), our liver's sugar storage capacity is exceeded and the excess sugar is converted by the liver into fatty acids and returned to the bloodstream, where istaken throughout the body and stored as fat. Excess insulin is the second problem. Insulin is a major hormone in the body, and is released in high levels anytime we ingest simple carbohydrates that are contained in fruit juice, white bread, most "wheat" bread, white rice, baked white potato, bagels, croissants, pretzels, sugary drinks, beer, and anything that has high fructose corn syrup on the nutritional label. Two actions occur when the insulin levels are spiked. First, the body's fat burning process is shut down so that the sugar that has just been ingested can be immediately used for energy. As soon as the muscles energy stores are full, the excess sugars are converted to fat. So, it all depends on what kind of carbohydrates a person is eating. To avoid de-stabilizing blood sugar levels one should stick to carbohydrates that do not trigger such a strong insulin response and instead provide long-term, stabilized energy like apples, oranges, pears, plums, grapes, bananas, grapefruit, oatmeal, brown rice, whole wheat spaghetti, whole grains, beans, lentils, milk, yogurt (preferably low-fat or fat-free) and soy. One should definitely stay away from processed and packaged foods as much as possible, because they are highly likely to include artificial sweeteners (which have a similar effect as sugar), and watch out for ingredients that include sucrose, maltose, dextrose, fructose, galactose, glucose, arabinose, ribose and lactose, experts advise as "the obesity epidemic and the problems with overeating don't have too much to do with people overeating fruits and healthy foods. They have a lot to do with people overeating excess sugars and fats," said Nicole Avena, a faculty member at the New York Obesity Research Center at Columbia University, who was not involved in the new study. Dr. Avena said that people "can have all the willpower in the world. But if the brain reward system is being activated in a way that causes them to have a battle against their willpower, then it can be very difficult for them to control their intake." The milkshakes used in the research were all made with chocolate syrup and an ice cream base. But the fat content was manipulated by using either half and half or 2 percent milk, and the sweetness was manipulated by varying the simple syrup content. Low fat, low sugar milkshakes activated regions of the brain associated with taste and sensation, but they had no impact on reward regions. These brain regions, called the food-reward system, control our desire for food: the more active they are, the more we want to eat. The researchers found that increasing the fat content of a high sugar shake did not activate the reward region any further. Relatively high fat, low sugar milkshakes, however, did engage part of the reward circuitry. And a high sugar shake that had triple that amount of sugar but only a quarter of the fat had an even greater impact. Dr. Stice said he was surprised because he expected fat would be a stronger stimulus than sugar. But he also noted that the human brain is hardwired to prefer sweet flavors. "When we're children, we prefer high sugar foods right away, but not high fat," he said. "We develop preferences for fat, but we're basically born with a preference for sugar." Dr. Stice said the bulk of brain research on fat and sugar was pointing to the idea that addressing societal problems with overeating should start with sugar. "If you look at our American diet, most people are consuming considerably more sugar than fat," he said. "We've really ramped up the sugar in our diets, but we've backed off on fat." In her own research, Dr. Avena has found that sugar and fat influence brain chemistry and behavior when consumed in large quantities. Animals given small amounts of each do not show many changes. But when they are given unlimited access to either, those that gorge on sugar in particular show changes in their opiate receptors — which help regulate pain, reward and euphoria — and when the sugar is suddenly taken away, they show signs of withdrawal. "These foods themselves are not inherently addictive through their taste per se," said Dr. Ludwig, the director of the New Balance Foundation Obesity Prevention Center at Boston Children's Hospital. "It's the effects that they have on our metabolism. If our blood sugar is stable, we can walk by a bakery and be much less tempted than if our blood sugar is crashing. Your brain knows these foods are going to rescue low blood sugar. But then this sets up the next cycle." Meanwhile, researchers from Manchester have launched a new study to determine whether blood sugar levels during pregnancy, lower than the level used to diagnose gestational diabetes, influences later levels of body fat in children and development of diabetes in mothers after giving birth. The team from The University of Manchester and Central Manchester NHS Foundation Trust are trying to trace mothers and children who took part in an earlier research project 12 years ago.The original study, the Hyperglycemia and Pregnancy Outcomes (HAPO), looked at 2400 mothers from Manchester who were part of 23,316 mother-child pairs worldwide. They found that a mother's blood sugar levels, even short of diabetes, were associated with how heavy or fat her baby was. Avni Vyas, from The University of Manchester's Institute of Human Development, said: "We know that heavy babies are more likely to become overweight as children and that mothers with poor health and early signs of diabetes in pregnancy are at increased risk of having adverse outcomes at delivery such as; shoulder dystocia, caesarean sections and babies that are overweight and possibly hyperglycaemic. These children then go on to become unhealthy in later life and the cycle is perpetuated." Some 800 mothers and their children (now aged 8 to 12 years) will have their height, weight, blood pressure, body fat, blood sugar, insulin, and blood fats measured as part of new experiment. Dr Michael Maresh, Obstetrician at St Mary's Hospital, Manchester, said: "The original study has helped us to better understand the relationship between blood sugar levels in pregnancy and whether they are related to increased risk for the mother having complications during delivery or her baby having problems. As a result of this important study, medical and public health opinion regarding healthy blood sugar levels in pregnancy is changing. It is now becoming common practice to aim to have lower blood sugar levels during pregnancy than was originally accepted." Professor Peter Clayton, Paediatric Endocrinologist at the Manchester Children's Hospital and Professor of Child Health and Paediatric Endocrinology at The University of Manchester, added: "If we can determine risk factors for obesity early in life, then we have the opportunity to do something about it. This could help to prevent some of thelater life consequences of obesity, such as heart disease and diabetes. Sugar makes you fat and fat free food isn't really free of fat. Source: http://sputniknews.com/Image: flickr.com

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