Gastric Bypass May Alter the Brain
What to Know
Gastric bypass, a type of weight-loss surgery that shrinks the stomach and reroutes part of the intestines, touts numerous long-term benefits. It lowers blood pressure and cholesterol, and it leads to better blood glucose management. Many people with type 2 diabetes see a remission of the disease following surgery. The procedure may also bump up life expectancy. But the dramatic weight loss the surgery provides does not account for all these benefits. Gastric bypass also appears to alter certain brain functions and hormones in the gut. What role do such changes play after surgery? That’s what researchers were hoping to find out.
Researchers in the United Kingdom recruited 42 participants, ages 23 to 46. Most were white women, and none had diabetes. They were divided into three groups. Nine people who had a gastric bypass within the previous five to 31 months were in the study group. The other groups—21 obese people in one, 12 normal-weight people in the other—served as comparisons. Each participant underwent several brain scans during the study. They also were served Häagen-Dazs vanilla ice cream so that the researchers could measure how their brains and gut hormones responded to food consumption.
The brain scans showed that the hypothalamus and the pituitary both worked harder to control the urge to eat in the people who had gastric bypass surgery. Also, after surgery, a brain region called the medial orbital cortex lit up when eating, an indication of displeasure. Other brain activity suggests that eating becomes more of a chore after the operation. Another significant find: While the brains of obese people cease sending signals to stop eating, gastric bypass surgery seems to restore that signal. Finally, an increase in certain gut hormones (or peptides) after surgery may signal the brain that eating offers less of a reward after surgery.
Gastric bypass surgery may encourage weight loss by altering how the brain responds to food and eating, the authors of the study conclude. Post surgery, participants had less of a desire to eat, took less pleasure from food, got full from smaller portions, and were less likely to overindulge. However, the surgery and its aftermath both have serious potential health risks. Excessive bleeding and infection can occur during the procedure. Some people who had the surgery developed complications such as bowel obstructions, gallstones, hernias, and dumping syndrome, which causes diarrhea, vomiting, and/or nausea.
“Differences in Regional Brain Responses to Food Ingestion After Roux-en-Y Gastric Bypass and the Role of Gut Peptides: A Neuroimaging Study.” Katharine F. Hunt, Joel T. Dunn, Carel W. le Roux, Laurence J. Reed, Paul K. Marsden, Ameet G. Patel and Stephanie A. Amiel. Diabetes Care 2016 Oct; 39(10): 1787-1795