Bariatric surgery is an appealing weight loss option for many Americans for whom diet and exercise has not been an effective means of weight loss. The Roux en Y gastric bypass surgical procedure creates a very small pouch out of the stomach and reconnects this new pouch to a latter portion of the intestine. This limits the contact food has with absorptive tissues in the intestine as well as severely limiting the portion of food patients can consume at one time.
Anecdotally, patients report a decreased preference for sweet tasting and fatty foods after their surgery. Alan Spector, PhD, from Florida State University, hopes his research can help to identify a mechanism behind this phenomenon in an animal model. His work is part of a translational research project which will ultimately integrate human research being conducted in Ireland with his results in an animal model.
Dr. Spector designed a study that analyzed food intake of rats before and after bariatric surgery. The rats were familiarized with five food items with specific macronutrient compositions before surgery: refried beans (low sugar, low fat), low fat yogurt (low fat, high sugar), creamy peanut butter (high fat, low sugar), and sugar fat “whip” (high fat, high sugar). After a healing period where post-surgery weight loss and healing occurred, the intervention began.
On the first day of the reintroduction of the different food groups, the proportions of macronutrient intake between the gastric bypass rats and controls were the same. However, as days passed, rats with gastric bypass decreased their proportion of fat intake significantly compared to control animals. Fat intake was replaced by carbohydrate and protein but it is important to note that intake from “added sugars” remained constant–implying the majority of the changes came from increasing refried bean consumption and decreasing sugar whip intake. Importantly, the change happened over time, and considering this, Dr. Spector theorizes that change in intake is taking place due to the experiences of the rats, rather their their taste preferences specifically (1).
These findings set the stage for exciting research in the future in the path to identify the mechanisms behind what is causing the behavior change anecdotally observed in humans. However, it is extremely interesting to see the observed human behavior change in rats, and implies there is a mechanism to be identified. Practitioners, especially Registered Dietitians, can benefit from this information. Many patients, because of insurance purposes, must go through intensive lifestyle counseling before and after surgery. Informing patients of the changes they will experience is crucial. Though Dr. Spector’s research doesn’t say with certainty what changes in the body may be driving taste preferences, his research does support what observational data has already concluded. Counseling on issues such as dumping syndrome as well as food preference changes can prepare patients for what to expect after such a life changing procedure.
- Alan Spector. Taste, Palatability, Food Selection and Gastric Bypass. University of Georgia. Department of Foods and Nutrition Seminar Series. October 5, 2016.