Bariatric Surgery and Weight Loss Make Brain Say Meh to Sweets

TOPLINE:

A preference for less sweet beverages after bariatric surgery and weight loss appears to stem from a lower brain reward response to sweet taste without affecting the sensory regions.

METHODOLOGY:

• Previous studies have suggested that individuals undergoing bariatric surgery show reduced preference for sweet-tasting food post-surgery, but the mechanisms behind these changes remain unclear.
• This observational cohort study aimed to examine the neural processing of sweet taste in the reward regions of the brain before and after bariatric surgery in 24 women with obesity (mean body mass index [BMI], 47) who underwent bariatric surgery and 21 control participants with normal to overweight (mean BMI, 23.5).
• Participants (mean age about 43 years; 75%-81% White) underwent sucrose taste testing and functional MRI (fMRI) to compare the responses of the brain with sucrose solutions of 0.10 M and 0.40 M (akin to sugar-sweetened beverages, such as Coca-Cola at ~0.32 M) and Mountain Dew at ~0.35 M) versus water.
• In the bariatric surgery group, participants underwent fMRI 1-117 days before surgery, and 21 participants who lost about 20% of their weight after the surgery underwent a follow-up fMRI roughly 3-4 months later.
• The researchers analyzed the brain’s reward response using a composite activation of several reward system regions (the ventral tegmental area, ventral striatum, and orbitofrontal cortex) and of sensory regions (the primary somatosensory cortex and primary insula taste cortex).

TAKEAWAY:

• The perceived intensity of sweetness was comparable between the control group and the bariatric surgery group both before and after surgery.
• In the bariatric surgery group, the average preferred sweet concentration decreased from 0.52 M before surgery to 0.29 M after surgery (P = .008).
• The fMRI analysis indicated that women showed a trend toward a higher reward response to 0.4 M sucrose before bariatric surgery than the control participants.
• The activation of the reward region in response to 0.4 M sucrose (but not 0.1 M) declined in the bariatric surgery group after surgery (P = .042).

IN PRACTICE:

“Our findings suggest that both the brain reward response to and subjective liking of an innately desirable taste decline following bariatric surgery,” the authors wrote.

SOURCE:

This study was led by Jonathan Alessi, Indiana University School of Medicine, Indianapolis, and published online in Obesity.

LIMITATIONS:

The study sample size was relatively small, and the duration of follow-up was short, with recruitment curtailed by the COVID-19 pandemic. This study did not assess the consumption of sugar or sweetened food, which could provide further insights into changes in the dietary behavior post-surgery. Participants included women only, and the findings could have been different if men were recruited.

DISCLOSURES:

This study was funded by the American Diabetes Association, Indiana Clinical and Translational Sciences Institute, and National Institute on Alcohol Abuse and Alcoholism. Three authors reported financial relationships with some pharmaceutical companies outside of this study.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication. A version of this article appeared on Medscape.com.