A new study has revealed that people who have had a gastric bypass surgery not only will eat less, but also start to eat more healthily.
The findings suggest a new mechanism by which some types of bariatric surgery lead to long-term weight loss.
In one study, some obese people were randomly assigned either gastric bypass surgery or another type of operation, vertical-banded gastroplasty, in which the stomach volume is reduced but no part of the intestine is bypassed.
The participants who had had gastric bypass had a significantly smaller proportion of fat in their diet six years after surgery, based on questionnaire responses.
In another experiments, rats that had gastric bypass surgery ate less food in total, but they specifically ate less high fat food and more low fat food.
"It seems that people who've undergone gastric bypass surgery are eating the right food without even trying," said Torsten Olbers from Imperial College London, who performed the operations on patients in the study at Sahlgrenska University Hospital in Goteborg, Sweden.
Lead researcher Dr Carel le Roux said: "It appears that after bypass surgery, patients become hungry for good food and avoid junk food not because they have to, but because they just don't like it any more.
" If we can find out why this happens, we might be able to help people to eat more healthily without much effort," he added.
The study was published in the American Journal of Physiology-Regulatory, Integrative, and Comparative Physiology.