Table 1

Paradox between bariatric (RYGB) surgery and pharmacological interventions for obesity

RYGB surgeryPharmacological interventions
Body weight lossUp to 33%Up to 10%
Body weight loss maintenanceSustained loss of up to 18% of BW over 15 yearsPoorly sustained over 2 years
Rate of weight lossRapid within first yearSlow—steady
Reduce cardiovascular mortalityYesUnproven to date; studies ongoing
Insulin resistanceImprovement to resolution of insulin resistanceNo effect
DyslipidaemiaMild improvementNo change
HypertensionSignificant improvementMild improvement
Mechanism of action
 HypothalamusQuestionable effectL: Increase POMC pathway via 5HT2c receptor
P-T: noradrenergic—dopaminergic pathways; unclear mechanism
 BrainstemUnclearNo effect
 Vagus nerveCuts gastric branches of vagus nerveNo effect
 GI hormonesIncrease GLP-1, PP, PYY, OXM (especially early postprandially)No effect
 Effective gastric reservoir sizeDecreasedNo effect
Side effectsMainly surgery related nutrients deficiencyLorcaserin and Topiramate-Phentermine (ER) may have CNS side effects
  • CNS, central nervous system; L, Lorcaserin; OXM, oxyntomodulin; POMC, pro-opiomelanocortin; P-T, Phentermine-Topiramate Extended Release (ER); PYY, Peptide tyrosine–tyrosine; RYGB, Roux-en-Y gastric bypass.