Greater preconscious attention to food in severe obesity may explain weight regain after bariatric surgery
Among a cohort of adults who underwent weight-loss surgery, those with severe obesity before surgery showed a greater preconscious attentional bias response to food stimuli compared with adults whose obesity was less extreme, suggesting that a subconscious response to food may drive weight regain among some adults, according to findings accepted for presentation at the Endocrine Society Annual Meeting.
“Eating behavior is still too poorly understood,” Rogério Friedman, MD, PhD, professor of internal medicine at Universidade Federal do Rio Grande do Sul and head of the endocrine division at Hospital de Clínicas de Porto Alegre, Brazil, told Healio. “It may be the key for understanding how obesity occurs and how it is maintained. Specifically, our study suggests that behavioral and cognitive phenomena remain even after a rather radical treatment such as bariatric surgery, and these may come to explain the therapeutic success or lack of in the medium and long term.”
Defining attentional bias
Attentional bias is a cognitive phenomenon defined as attention drawn to a particular stimulus during a conscious phase, when the person can make a choice, or during a preconscious or automatic phase, when a person is drawn by impulses, according to Friedman.
“Attentional bias to visual food stimuli is one of the cognitive components that seem to contribute to the onset and course of obesity,” Friedman said during a presentation to the media.
Friedman and colleagues analyzed data from a cohort of 59 adults with obesity who underwent Roux-en-Y gastric bypass between 2010 and 2016 (mean presurgical BMI, 49.7 kg/m²; 78% white). Researchers assessed information on impulsivity and binge eating, as well as attentional bias using the dot-probe computerized task method.
“On the computer screen, a plus sign appears first,” Friedman said during the presentation. “It is rapidly replaced by a set of two images, one of which is food, the other has visual elements that resemble food. Each pair of images is shown for 100, 500 or 2,000 milliseconds ... 100 evaluates automatic attention; 500, preconscious and 2,000, conscious attention.”
The pictures then disappear, leaving an arrow under the food image or under the nonfood image, Friedman said. The participant must then indicate the direction of the arrow on a keypad. If the participant chooses the correct answer predominantly for food images, there is attentional bias, Friedman said.
Within the cohort, 91.5% scored above the cutoff point for binge eating disorder and 76.3% scored above the cutoff point for impulsivity. Mean BMI after surgery (within 30 days of assessment) was 33.6 kg/m²; postoperative follow-up time at assessment was 47.76 months.
The overall sample showed food attentional bias (mean, 16.3) when food stimuli were exposed during 2,000 milliseconds, suggesting a conscious attention toward food stimuli (P = .025).
Effect of severe obesity
In analyses stratified by severely obese status, defined as a BMI of at least 50 kg/m², researchers found that food attentional bias was higher among those with severe obesity before bariatric surgery (mean, 24.06 vs. –12.98) when food stimuli were exhibited during 500 milliseconds, indicating a preconscious attention to food stimuli compared with those without severe obesity before surgery (P = .008). At 500 milliseconds, attentional bias value was different from 0 only among participants with severe obesity before surgery (P = .01), indicating an attentional bias to food stimuli when attention orientation was less possible.
“Originally, we thought that attentional bias would still be present in all subjects after surgery, and that it would be present in all three phases of attention,” Friedman said. “Our finding that conscious attentional bias is there for most patients, whereas preconscious bias is seen mostly in the most severe class of disease, was a little bit of a surprise. It indicates that unconscious phenomena may be operating to drive formerly superobese patients to eat in a somewhat disadvantageous way, thus leading to weight regain.” – by Regina Schaffer
Friedman R, et al. MOND-604. The Endocrine Society Annual Meeting; 2020 (conference canceled/virtual meeting).
Disclosure: Friedman reports no relevant financial disclosures.