Medical and Surgical Treatments for Obesity Have Opposite Effects on Peptide YY and Appetite: A Prospective Study Controlled for Weight Loss

Abstract

Context:The effects of medical and surgical treatments for obesity on peptide YY (PYY) levels, in patients with similar weight loss, remain unclear.Objective: The objective of the study was to assess PYY and appetite before and after Roux-en-Y gastric bypass (RYGB), sleeve gastrectomy (SG), and medical treatment (MED).Design: This was a prospective, controlled, nonrandomized study. Setting:The study was conducted at the Departments of Nutrition and Digestive Surgery at a university hospital.Participants: Participants included three groups of eight patients with similar body mass indexes (RYGB 37.8 Ϯ 0.8, SG 35.3 Ϯ 0.7, and MED 39.1 Ϯ 1.7 kg/m 2 , P ϭ NS) and eight lean controls (body mass index 21.7 Ϯ 0.7 kg/m 2 ). Main Outcome Measures:Total plasma PYY, hunger, and satiety visual analog scales in fasting and after ingestion of a standard test meal were measured.Results: At baseline there were no differences in the area under the curve (AUC) of PYY, hunger, or satiety in obese groups. Two months after the interventions, RYGB, SG, and MED groups achieved similar weight loss (17.7 Ϯ 3, 14.9 Ϯ 2.4, 16.6 Ϯ 4%, respectively, P ϭ NS). PYY AUC increased in RYGB (P Ͻ 0.001) and SG (P Ͻ 0.05) and did not change in MED. PYY levels decreased at fasting, 30 min, and 180 min after a standard test meal in MED (P Ͻ 0.05). Hunger AUC decreased in RYGB (P Ͻ 0.05). Satiety AUC increased in RYGB (P Ͻ 0.05) and SG (P Ͻ 0.05). Appetite did not change in MED. PYY AUC correlated with satiety AUC (r ϭ 0.35, P Ͻ 0.05).Conclusion: RYGB and SG increased PYY and reduced appetite. MED failed to produce changes. Different effects occur despite similar weight loss. This suggests that the weight-loss effects of these procedures are enhanced by an increase in PYY and satiety. O ver the last 30 yr, the prevalence of obesity has increased worldwide, becoming one of the world's most important public health problems and resulting in great efforts toward the development of strategies to treat this condition (1). However, medical interventions for obesity, including diet, physical activity, behavioral therapy, and weight loss drugs, are associated with poor weight reduction and are difficult to sustain in the long term (2). These modest results can be explained by several factors, one being that the human body responds to weight

Roux-en-Y gastric bypass and laparoscopic sleeve gastrectomy: understanding weight loss and improvements in type 2 diabetes after bariatric surgery

“…Increases in meal-stimulated PYY levels occur at 1 wk after LSG (153), are sustained at 12 mo (84,203), and can be equivalent to those after RYGB (84,153,203). Corollary changes in meal-stimulated GLP-1 are observed, but are less marked than after RYGB (84,153).…”

“…This occurs as early as day 2 after RYGB, and before weight loss occurs (110), indicating this is a direct consequence of surgery, and equivalent weight loss from dieting (203) or LAGB (19) does not similarly alter PYY. The most likely cause for this difference is surgical rerouting of gut content.…”

“…to A: As hungry as I have ever felt.). While this might imply causality, most studies do not correlate changes in PYY with VAS (92,94,130,203). One explanation is inadequate statistical power, as VAS scores lack sensitivity (19).…”

Roux-en-Y gastric bypass: effects on feeding behavior and underlying mechanisms

“…Notably, in the case of RYGBP, the sustained body weight reduction occurs despite dramatic falls in circulating leptin levels (35). However, RYGBP-induced gut hormonal changes contrast strongly with those seen after dieting, as the former result in reduced hunger and more satiety, which lead to sustained weight loss (36). Thus, it has been postulated that altered humoral or neural signals, which originate in the gut and are transmitted to the brain, are responsible for the resetting of body weight set-point induced by RYGBP (Figure 2 …”

Bariatric Surgery and Bone Loss: Do We Need to Be Concerned?

“…Postprandial PYY levels have been shown to increase in response to RYGB [132] and sleeve gastrectomy [133], while it remains unclear whether gastric banding has any comparable effects on fasting or postprandial circulating PYY levels [134].…”