There Are No Pluses for Obesity

"It has been suggested that body composition itself might somehow affect the neural systems that underlie cognition, motivation, self-control and salience processing, which would in turn affect one's ability to make better lifestyle choices."
Study, published in journal Frontiers in Neuroscience

"We looked for changes across the whole brain, but we also looked at specific networks. And there was no significant difference in terms of white matter volume, globally speaking."
"[Therefore] it stands to reason that these changes could further affect the ability of overweight individuals to exert self-control and maintain healthy lifestyle choices."
"[More and large studies are needed] but there's growing awareness that obesity impacts not just physical health, but mental health."
Chase Figley, assistant professor, department of radiology, University of Manitoba/Winnipeg Health Sciences Centre

Sean Gallup/Getty Images      The study's findings appear to fit with mounting evidence linking higher body mass with poorer impulse control and other “cognitive deficits.”

This is not the first such study indicating that obesity has its deleterious effects not only physically but also on the capacity of a hugely overweight individual's ability to think as intelligently as someone whose brain isn't challenged by obesity. Just as fat around the mid-section begins to crowd the viscera and generalized fat affects joints, while likelihood of diabetes onset and heart and stroke potentials are increased, people carrying far too much weight are seen to be burdened with reduced cognitive functioning.

This new study, a joint research project between Canadian and American scientists, whose findings were recently published, posits that obese and overweight people suffer significantly less grey and white matter in the networks of their brain, a finding considered to represent a "biologically plausible explanation" why such people are beset with greater impulsivity and "altered reward processing".

Brain images of 32 healthy adult volunteers who happened to be greatly overweight, from two Baltimore Maryland neighbourhoods, formed the participants of the study. The findings make a neat fit with evidence steadily on the increase that higher body mass is linked with poorer impulse control, among other "cognitive deficits", all of which may be involved in detracting from the success of an overweight individual's efforts to lose some of that weight.

Obesity has been found responsible by other researchers to accelerated, age-related brain shrinkage leading to early onset dementia, as well. An estimated 2.1-billion people are in the overweight or obese category globally. In Canada alone in 2014, 20 percent of adults representing about 5.3-million people had reported height and weight statistics classifying them as obese.

Researchers for the study imaged the brains of 16 men and an equal number of women with no  history of mental health problems, measuring BMI and body fat percentages, then looked to measure individual differences in body composition and how they might be related to differences in brain structure and function.

People with a higher BMI (body fat count) had slightly more grey matter but when different specific networks were examined it was found that heavier people had less grey and white matter in the "salience network", explained by Dr. Figley as the "seat of motivation, willpower, and the ability to persevere through physical and emotional challenges".

Differences were discovered as well, based on body composition in an area of the brain responsible for habitual behaviour. Obesity has been shown to be associated with lower scores on decision-making and executive function tasks, slower mental processing speed and decreased learning and memory, by numerous other studies, pointed out Dr. Figley.

A conundrum does present itself, however, and that is which comes first. Do brain differences predispose certain individuals to becoming overweight or obese, "Or are these differences more likely to be an effect of poor diet, lifestyle and/or body composition", ask the study's authors.While the study doesn't address that issue, "there are previous studies that imply elevated body fat can cause these sorts of brain changes".