Comparative Efficacy and Safety of Sleeve Gastrectomy versus Roux‑en‑Y Gastric Bypass

Anatomical and Mechanistic Differences

Sleeve gastrectomy removes roughly two‑thirds to three‑quarters of the stomach along the greater curvature, creating a tubular conduit based on the lesser curvature, thereby providing restriction‑driven weight loss【3】【4】.
The primary mechanism of sleeve gastrectomy is restriction; the reduced gastric capacity produces early satiety【3】.
Removal of the gastric fundus in sleeve gastrectomy lowers ghrelin production, contributing to hormonal appetite suppression【4】.
Compared with bypass procedures, sleeve gastrectomy has minimal impact on nutrient absorption【1】【2】.
Roux‑en‑Y gastric bypass constructs a small gastric pouch of approximately 15–30 mL (≈1 oz) from the proximal stomach【1】【5】【4】.
The bypass connects this pouch directly to the mid‑jejunum, excluding the stomach remnant, duodenum, and proximal jejunum from the alimentary stream【1】【4】.
Roux‑en‑Y combines restrictive and malabsorptive mechanisms to achieve weight loss【1】【2】.
Hormonal changes after Roux‑en‑Y are mediated by bypassing the duodenum and altering pancreatic outflow【4】.

Sleeve gastrectomy yields an average total body weight loss of about 25 % (equivalent to 38–79 % excess weight loss)【3】【4】【1】.
Roux‑en‑Y gastric bypass achieves a total body weight loss of 25–45 % (50–80 % excess weight loss)【3】【4】.

Both procedures have low peri‑operative mortality, reported at 0.1–0.3 % overall【6】.
Long‑term complications of sleeve gastrectomy include gastric stenosis and staple‑line dehiscence (<1–2.7 %), chronic gastro‑esophageal reflux disease, esophagitis, and Barrett’s esophagus【3】【4】.
Long‑term complications of Roux‑en‑Y gastric bypass include internal hernia, marginal ulceration (2.5–5 %), anastomotic leaks (0.6–4.4 %), and stenosis (8–19 %)【7】.
Nutritional deficiencies are more pronounced after Roux‑en‑Y gastric bypass due to its malabsorptive component【1】【8】.

Relative contraindications to sleeve gastrectomy are established Barrett’s esophagus and refractory gastro‑esophageal reflux disease【3】【4】.
Contraindications to Roux‑en‑Y gastric bypass include inflammatory bowel disease and clinical situations requiring precise medication absorption (e.g., post‑transplant immunosuppression)【3】【4】.
Choose Roux‑en‑Y gastric bypass when the patient has pre‑existing gastro‑esophageal reflux disease or Barrett’s esophagus【3】【4】.
Choose sleeve gastrectomy when the patient requires medications with strict absorption requirements or has inflammatory bowel disease【3】【4】.

Sleeve gastrectomy has become the most frequently performed bariatric operation worldwide, surpassing Roux‑en‑Y about a decade ago【1】【2】【8】.
Roux‑en‑Y gastric bypass remains the procedure with superior metabolic outcomes and greater weight loss, particularly for patients with severe metabolic disease or pre‑existing reflux【3】【4】.
Both procedures mandate lifelong nutritional monitoring; however, Roux‑en‑Y requires more intensive micronutrient supplementation (including thiamine, vitamin B12, folate, iron, vitamin D, calcium, vitamins A/E/K, zinc, and copper) because of its malabsorptive effect【7】.