January 24, 2018
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Imaging shows women more responsive to ‘rewarding’ foods

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Women in a fasted state are more likely to respond to hedonic food cues, such as images of cake or pizza, compared with so-called neutral foods, whereas in men, the propensity to gain weight may influence visual food cue responses, according to findings published in Obesity.

“This study is the first to investigate whether sex-based differences in neuronal responses to food cues vary based on hedonic properties of foods, by comparing responses to foods with high vs. neutral hedonic value,” Kristina T. Legget, PhD, assistant professor in the department of psychiatry at Anschutz Medical Campus, University of Colorado, and colleagues wrote in the study background. “This is also the first study to determine whether sex-based differences in neuronal responses to food cues vary based on the propensity to obesity, with the inclusion of both obesity-prone and obesity-resistant study groups.”

Legget and colleagues analyzed data from 56 adults aged 25 to 40 years, drawn from a larger study investigating the effects of propensity for obesity on metabolism. Within the cohort, 28 participants were considered to have a propensity to be resistant to weight gain and obesity (BMI, 17-25 kg/m²; never having overweight despite no attempts to lose weight) and 28 participants were identified as being prone to weight gain and obesity (BMI, 20-30 kg/m²; and a history of weight fluctuations). All participants were weight-stable for the 3 months before the study. Participants underwent body composition assessments via DXA, and competed the Three-Factor Eating Questionnaire before a 4-day eucaloric run-in diet (50% carbohydrate, 30% fat and 20% protein). On study day, participants consumed a liquid breakfast meal before undergoing functional MRI while viewing visual stimuli from three categories: non-food objects, foods of high hedonic value (chocolate cake, bacon, pizza) and foods of neutral hedonic value (bagels, fruit, cereal). Final analysis included 25 women and 28 men.

In reviewing functional MRI results, researchers observed a greater response to hedonic foods in the fasted state among women vs. men in the nucleus accumbens (P = .0002) and insula (P = .01). There were no between-group differences observed in the fed state.

In the fed state, researchers observed a greater response to foods vs. non-foods among those with a propensity for obesity compared with obesity-resistant participants in the dorsolateral prefrontal cortex (P < .001), the anterior cingulate cortex (P = .005) and the insula (P = .008). Additionally, there was a greater response observed in the nucleus accumbens in men with propensity for obesity vs. obesity-resistant men (P = .009).

The researchers noted that the observed differences were specific to the more nuanced comparison of hedonic vs. neutral foods and were not present when considering all foods with non-food objects. The results, they added, suggest that women “may be more sensitive than men to salient and rewarding aspects of food when fasted.”

“This suggests potentially different mechanisms underlying weight gain and maintenance in women compared with men, supporting the use of different weight-loss and maintenance strategies,” the researchers wrote. “These finding also suggest that the neurophysiology underlying obesity propensity may be distinct between the sexes.” – by Regina Schaffer

Disclosures: The authors report no relevant financial disclosures.