In the last post, we discussed differences in ghrelin production after gastric bypass and sleeve gastrectomy. Today the studies we are going to consider describe the effects of gastric banding and sleeve gastrectomy on ghrelin and weight loss variables.
Langer et al. randomly assigned (love it!) 20 patients to either gastric banding or sleeve gastrectomy. The groups were well-matched on demographics and medical co-morbidities. The researchers measured plasma ghrelin levels at 4 time periods: preoperatively, 1 day after surgery, 1 month after surgery, and 6 months after surgery.
The results are consistent with what we saw in the last post, specifically, that the sleeve gastrectomy produced a significant, immediate and long-term decrease in plasma ghrelin levels. Most ghrelin is produced by the stomach in an area called the gastric fundus, and that part is simply removed by the sleeve gastrectomy. No more fundus, much less ghrelin.
And what about the banding? No change in ghrelin was seen after 1 day, but a significant increase occurred after 1 month and 6 months. Again, this is consistent with other studies we have examined . . . weight loss by dieting or other surgical techniques results in an increase in ghrelin. This is one way to understand yo-yo dieting and what used to be called the setpoint theory of body weight.
Himpens et al. compared other variables in 2 groups of randomly assigned (about to swoon!) patients, namely, weight loss, loss of feeling of hunger, loss of craving for sweets, new diagnoses of gastroesophageal reflux disease (GERD), and surgical complications.
Can you guess the results? Based on what we are learning about ghrelin, you might predict that the only significant differences would be in weight loss and loss of feeling of hunger . . . and you would be right. Specifically, sleeve gastrectomy patients had lost significantly more weight than the gastric banding patients after 1 year and 3 years, and they felt significantly less hunger at the same time points.
And the researchers like this as a working hypothesis . . . that decreased ghrelin production results in appetite suppression and weight loss. However, they also introduce another mechanical factor, the effect of gastric emptying on appetite, and they associate this change with the new anatomy of the stomach after sleeve gastrectomy. I need to read up on this, and maybe consult someone who knows more about this than I do, and get back to you.
The take-away message I want to send to everyone who struggles with their weight is this . . . there are serious and likely redundant biochemical mechanisms that are working to maintain your weight where it is. Sometimes, when it seems like your appetite has a mind of its own, maybe it does. Lighten up on yourself. Keep working to maintain health-promoting behaviors, but don't beat yourself up for being human.
Langer, F., Reza Hoda, M., Bohdjalian, A., Felberbauer, F., Zacherl, J., Wenzl, E., Schindler, K., Luger, A., Ludvik, B., & Prager, G. (2005). Sleeve Gastrectomy and Gastric Banding: Effects on Plasma Ghrelin Levels Obesity Surgery, 15 (7), 1024-1029 DOI: 10.1381/0960892054621125
Himpens, J., Dapri, G., & Cadière, G. (2006). A Prospective Randomized Study Between Laparoscopic Gastric Banding and Laparoscopic Isolated Sleeve Gastrectomy: Results after 1 and 3 Years Obesity Surgery, 16 (11), 1450-1456 DOI: 10.1381/096089206778869933