Posts tagged calories
Articles and news from the latest research reports.
Brain Activity Provides Evidence for Internal “Calorie Counter”
As you glance over a menu or peruse the shelves in a supermarket, you may be thinking about how each food will taste and whether it’s nutritious, or you may be trying to decide what you’re in the mood for. A new neuroimaging study suggests that while you’re thinking all these things, an internal calorie counter of sorts is also evaluating each food based on its caloric density.
The findings are published in Psychological Science, a journal of the Association for Psychological Science.
“Earlier studies found that children and adults tend to choose high-calorie food,” says study author Alain Dagher, neurologist at the Montreal Neurological Institute and Hospital. “The easy availability and low cost of high-calorie food has been blamed for the rise in obesity. Their consumption is largely governed by the anticipated effects of these foods, which are likely learned through experience.”
“Our study sought to determine how people’s awareness of caloric content influenced the brain areas known to be implicated in evaluating food options,” says Dagher. “We found that brain activity tracked the true caloric content of foods.”
For the study, 29 healthy participants were asked to examine pictures of 50 familiar foods. The participants rated how much they liked each food (on a scale from 1 to 20) and were asked to estimate the calorie content of each food. Surprisingly, they were poor at accurately judging the number of calories in the various foods, and yet, the amount participants were willing to bid on the food in a simulated auction matched up with the foods that actually had higher caloric content.
Results of functional brain scans acquired while participants looked at the food images showed that activity in the ventromedial prefrontal cortex, an area known to encode the value of stimuli and predict immediate consumption, was also correlated with the foods’ true caloric content.
Participants’ explicit ratings of how much they liked a food, on the other hand, were associated with activity in the insula, an area of the brain that has been linked to processing the sensory properties of food.
According to Dagher, understanding the reasons for people’s food choices could help to control the factors that lead to obesity, a condition that is linked to many health problems, including high blood pressure, heart disease, and Type 2 diabetes.
Old drug may point the way to new treatments for diabetes and obesity
Researchers at the University of Michigan’s Life Sciences Institute have found that amlexanox, an off-patent drug currently prescribed for the treatment of asthma and other uses, also reverses obesity, diabetes and fatty liver in mice.
The findings from the lab of Alan Saltiel, the Mary Sue Coleman director of the Life Sciences Institute, were published online Feb. 10 in the journal Nature Medicine.
"One of the reasons that diets are so ineffective in producing weight loss for some people is that their bodies adjust to the reduced calories by also reducing their metabolism, so that they are ‘defending’ their body weight," Saltiel said. "Amlexanox seems to tweak the metabolic response to excessive calorie storage in mice."
Different formulations of amlexanox are currently prescribed to treat asthma in Japan and canker sores in the United States. Saltiel is teaming up with clinical-trial specialists at U-M to test whether amlexanox will be useful for treating obesity and diabetes in humans. He is also working with medicinal chemists at U-M to develop a new compound based on the drug that optimizes its formula.
The study appears to confirm and extend the notion that the genes IKKE and TBK1 play a crucial role for maintaining metabolic balance, a discovery published by the Saltiel lab in 2009 in the journal Cell.
"Amlexanox appears to work in mice by inhibiting two genes—IKKE and TBK1—that we think together act as a sort of brake on metabolism," Saltiel said. "By releasing the brake, amlexanox seems to free the metabolic system to burn more, and possibly store less, energy."
A new study by University of North Carolina School of Medicine pediatrics researchers finds a surprising difference in the eating habits of overweight children between ages 9 and 17 years compared to those younger than 9.
Younger children who are overweight or obese consume more calories per day than their healthy weight peers. But among older overweight children the pattern is reversed: They actually consume fewer calories per day than their healthy weight peers.
How to explain such a seemingly counterintuitive finding?
“Children who are overweight tend to remain overweight,” said Asheley Cockrell Skinner, PhD, assistant professor of pediatrics at UNC and lead author of the study published online Sept. 10, 2012 by the journal Pediatrics.
“So, for many children, obesity may begin by eating more in early childhood. Then as they get older, they continue to be obese without eating any more than their healthy weight peers,” Skinner said. “One reason this makes sense is because we know overweight children are less active than healthy weight kids. Additionally, this is in line with other research that obesity is not a simple matter of overweight people eating more — the body is complex in how it reacts to amount of food eaten and amount of activity.”