Does gastric bypass surgery change body weight set point?

Area of Science:

• Obesity and metabolic regulation
• Neuroscience and endocrinology

Background:

• Stable adult body weight is maintained by a brain-based homeostatic mechanism regulating energy balance.
• Dieting often fails due to the body defending a higher set point for body weight, leading to weight regain.
• Bariatric surgery shows greater efficacy than dieting in achieving sustained weight loss and reduced food intake.

Purpose of the Study:

• To review behavioral evidence suggesting bariatric surgery reprograms the body weight defense mechanism.
• To explore the mechanisms underlying the sustained effects of Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy.

Main Methods:

• Non-systematic review of behavioral studies in rodents and humans.
• Analysis of rodent responses to overfeeding and underfeeding after bariatric surgery.
• Consideration of central and peripheral signaling pathways involved in weight regulation.

Main Results:

• Behavioral data indicate that RYGB and sleeve gastrectomy lower the defended body weight set point.
• Rodents subjected to these surgeries return to a lower preferred body weight after perturbations.
• The capacity for increased food intake post-surgery challenges the physical restriction hypothesis.

Conclusions:

• Bariatric surgery appears to physiologically reset the body's defended weight level.
• Mechanisms involve central leptin and melanocortin pathways, alongside peripheral signals like gut hormones.
• Further research using omics and genetic manipulation techniques is needed to elucidate these mechanisms.