Snacking and BMI linked to double effect of brain activity and self-control

ScienceDaily (July 23, 2012) — Snack consumption and BMI are linked to both brain activity and self-control, new research has found.

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The research, carried out by academics from the Universities of Exeter, Cardiff, Bristol, and Bangor, discovered that an individual's brain 'reward centre' response to pictures of food predicted how much they subsequently ate. This had a greater effect on the amount they ate than their conscious feelings of hunger or how much they wanted the food,

A strong brain response was also associated with increased weight (BMI), but only in individuals reporting low levels of self-control on a questionnaire. For those reporting high levels of self-control a stronger brain response to food was actually related to a lower BMI.

This study, which is now published in the journal NeuroImage, adds to mounting evidence that overeating and increased weight are linked, in part, to a region of the brain associated with motivation and reward, called the nucleus accumbens. Responses in this brain region have been shown to predict weight gain in healthy weight and obese individuals, but only now have academics discovered that this is independent of conscious feelings of hunger, and that self-control also plays a key role.

Following these results, academics at the University of Exeter and Cardiff have begun testing 'brain training' techniques designed to reduce the influence of food cues on individuals who report low levels of self-control. Similar tests are being used to assist those with gambling or alcohol addiction.

Dr Natalia Lawrence of Psychology at the University of Exeter, lead researcher in both the original research and the new studies, said: "Our research suggests why some individuals are more likely to overeat and put on weight than others when confronted with frequent images of snacks and treats. Food images, such as those used in advertising, cause direct increases in activity in brain 'reward areas' in some individuals but not in others. If those sensitive individuals also struggle with self-control, which may be partly innate, they are more likely to be overweight. We are now developing computer programs that we hope will counteract the effects of this high sensitivity to food cues by training the brain to respond less positively to these cues."

Twenty-five young, healthy females with BMIs ranging from 17-30 were involved in the study. Female participants were chosen because research shows females typically exhibit stronger responses to food-related cues. The hormonal changes during the menstrual cycle affect this reaction, so all participants were taking the monophasic combined oral contraceptive pill. Participants had not eaten for at least six hours to ensure they were hungry at the time of the scan and were given a bowl containing 150 g (four and a half packets) of potato chips to eat at the end of the study; they were informed that potato chip intake had been measured afterwards.

Researchers used MRI scanning to detect the participants' brain activity while they were shown images of household objects, and food that varied in desirability and calorific content. After scanning, participants rated the food images for desirability and rated their levels of hunger and food craving. Results showed that participants' brain responses to food (relative to objects) in the nucleus accumbens predicted how many potato chips they ate after the scan. However, participants' own ratings of hunger and how much they liked and wanted the foods, including potato chips, were unrelated to their potato chip intake.

This study was funded by the Wales Institute of Cognitive Neuroscience.

What this study shows:

Brain responses to food images vary considerably between individuals. Brain responses to food images but not conscious feelings of hunger or desire to eat predict subsequent potato chip consumption. Individuals' reported levels of self-control influence whether this brain response is associated with a higher or lower BMI.

What this study does NOT show:

Brain responses to food cues cause overeating. The associations reported here are true in everyone -- only healthy young women were included. Whether our brain response and levels of self-control are learned or innate.Share this story on Facebook, Twitter, and Google:

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Edible stop signs? A few red chips in the stack cut snacking in half

ScienceDaily (May 28, 2012) — Once you pop the top of a tube of potato chips, it can be hard to stop munching its contents. But Cornell researchers may have found a novel way to help: Add edible serving size markers that act as subconscious stop signs.

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As part of an experiment carried out on two groups of college students (98 students total) while they were watching video clips in class, researchers from Cornell's Food and Brand Lab served tubes of Lays Stackables, some of which contained chips dyed red.

In the first study of the research, which is published online this month in Health Psychology, a journal of the American Psychological Association, the red chips were interspersed at intervals designating one suggested serving size (seven chips) or two serving sizes (14 chips); in the second study, this was changed to five and 10 chips.

Unaware of why some of the chips were red, the students who were served those tubes of chips nonetheless consumed about 50 percent less than their peers: 20 and 24 chips on average for the seven-chip and 14-chip segmented tubes, respectively, compared with 45 chips in the control group; 14 and 16 chips for the five-chip and 10-chip segmented tubes, compared with 35 chips in the control group.

They were also better able to estimate how many chips they had eaten. Those in the control groups underestimated the amount of chips they had consumed by about 13 chips. Those in the "segmented" groups were able to guess within one chip.

"People generally eat what is put in front of them if it is palatable," said Brian Wansink, Cornell Food and Brand Lab director. "An increasing amount of research suggests that some people use visual indication -- such as a clean plate or bottom of a bowl -- to tell them when to stop eating."

"By inserting visual markers in a snack food package, we may be helping them to monitor how much they are eating and interrupt their semiautomated eating habits," he added.

Wansink, the John Dyson Professor of Consumer Behavior and author of the best-seller "Mindless Eating: Why We Eat More Than We Think," carried out the study with psychologists Andrew Geier of Yale University and Paul Rozin of the University of Pennsylvania.

"The effect demonstrated and replicated in these studies stands as perhaps the largest practicable procedure to decrease food intake in the literature," Wansink said. "Marking modest portion sizes promises to be an effective strategy in the attempt to reduce food intake and obesity."

He noted that the experiment reduced caloric intake among participants by about 250 calories.

"Very modest reductions in intake produced by environmental changes can, when cumulated, lead to substantial weight loss," Wansink said. "These studies could have major public health significance."

Wansink said further studies are needed among larger, more diverse groups to determine in what context segmentation cues work, exactly why they work and whether people will compensate for the reduction in food intake by eating more later.

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Snacking and Skipping Breakfast Linked to Type 2 Diabetes

The phrase “death by snacking” is not too far from the truth, especially if a person is overweight and struggles to lose weight.  Two new studies confirm the dangers of snacking, something I have been adamant about since the release of Mastering Leptin in 2002. 

Both studies appeared recently in the American Journal of Clinical Nutrition.  The first followed 29,206 U.S. men who were free of metabolic disease for 16 years.  It found that skipping breakfast was associated with a 21 percent increased risk for developing type 2 diabetes, which is why the Leptin Diet tells you to start your metabolic engines with a high protein breakfast.  This study also confirmed the relationship between a high BMI Body Mass Index. BMI is a statistical measurement of body weight based on the person's height and weight. It does not actually measure the body fat percentage but provides an estimation of a healthy body weight. Normal BMI for adults ranges from 18.5-24.9, snacking, and the risk for type 2 diabetes.

Another controlled human study found that snacking caused a loss of the ability to sense fullness, resulting in consumption of larger and larger snacks.  Snacking appears to induce a repetitive strain injury to your taste and pleasure system, making them numb to normal intake. 

The more food you eat, the fatter you are likely to become, which is news to nobody.  Figuring out how to feel satisfied on less food is the trick.  This is why following the Five Rules of the Leptin Diet is so important.

When you do not have leptin working to your advantage then leptin entry into your brain is decreased while leptin levels in your blood elevate, a problem known as leptin resistance.  In addition to leptin, the other important hormone made by your fat is adiponectin Protein hormone that modulates metabolism including glucose and fatty acid catabolism. High levels are associated with low body fat. .  Both of these hormones are made in tandem when you are metabolically healthy.  Once you develop leptin resistance, then your adiponectin Protein hormone that modulates metabolism including glucose and fatty acid catabolism. High levels are associated with low body fat. levels decline.  This causes insulin resistance and increased risk for type 2 diabetes.

It is just as important when you eat as what you eat.  It isn’t just an issue of how many calories you consume; it is also an issue of how efficiently you can metabolize the calories you do consume.  Eating in harmony with leptin is by far the best way to improve metabolic efficiency.

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