If you are reading this, you are probably at the stage of seriously considering gastric sleeve surgery, or you have already made the decision and want to understand exactly what you are agreeing to. Either way, this article is for you. We want to give you a clear, honest explanation of what a gastric sleeve actually is and how the surgery works, based on our own experience and the medical information we gathered before our procedures in March 2024.
What is a gastric sleeve?
A gastric sleeve, formally known as a sleeve gastrectomy, is a type of bariatric surgery in which approximately 75 to 80 percent of the stomach is permanently removed. What remains is a narrow, tube-shaped pouch roughly the size and shape of a banana, sometimes described as a sleeve. The surgery does not involve any rerouting of the intestines, which distinguishes it from gastric bypass procedures.
The result is a stomach that holds significantly less volume than before. A normal adult stomach can expand to hold around one to 1.5 litres of food and liquid. After a sleeve gastrectomy, the remaining stomach typically holds around 100 to 150 millilitres at first, gradually increasing to around 200 to 300 millilitres over time.
How the surgery works
The procedure is performed laparoscopically, which means through several small incisions in the abdomen rather than a single large open incision. The surgeon inserts a camera and instruments through these small ports and removes the larger, outer curve of the stomach, known as the fundus and greater curvature.
Before making the cut, the surgeon typically inserts a calibration tube down the oesophagus into the stomach. This tube acts as a guide, ensuring the remaining sleeve is formed to a consistent size and that the cut is made in the correct position. The remaining stomach tissue is then stapled closed along the cut line using surgical staples.
The removed portion of the stomach is extracted through one of the port sites and the procedure is complete. The whole operation typically takes between 60 and 90 minutes, though this varies depending on individual anatomy and surgical team experience.
Why removing part of the stomach helps with weight loss
The most obvious mechanism is restriction. A smaller stomach means you physically cannot eat as much at one sitting. Portion sizes that would previously have been comfortable become too large, and eating past your new limit causes discomfort, nausea, or vomiting.
But restriction alone does not fully explain the weight loss results. The removed portion of the stomach, particularly the fundus, is the primary site of production for ghrelin, the hormone that drives hunger. After surgery, circulating ghrelin levels drop significantly. This is why many people report feeling genuinely less hungry after a gastric sleeve, particularly in the first year. The procedure changes the hormonal environment, not just the physical capacity of the stomach.
James was around 30 stone before surgery. Within the first year he had lost more than 12 stone. Kirsten was around 18 stone and lost more than 8 stone in the same period. The combination of restricted intake and reduced appetite drove consistent, sustained loss in a way that years of dietary changes alone had not achieved.
What makes it different from other procedures
Unlike gastric bypass, the gastric sleeve does not alter the digestive pathway. Food still travels through the stomach, then the small intestine, then the large intestine in the normal sequence. This means absorption of nutrients, including vitamins and minerals, follows the same route as before. Supplementation is still required, but the malabsorption risks associated with bypass procedures do not apply.
Unlike a gastric band, the gastric sleeve involves no implanted device. There is no adjustable band, no port under the skin, no risk of band slippage or erosion, and no need for ongoing band adjustments. The surgery permanently changes the anatomy without leaving a foreign object in the body.
Is it reversible?
No. This is a point that every reputable surgeon and bariatric team will make very clearly, and it is one that we thought about carefully before committing. The removed portion of the stomach cannot be reattached. The procedure is permanent. The sleeve can be revised to a gastric bypass or duodenal switch at a later point if required, but the sleeve itself cannot be undone. This permanence was one of the most important things we had to sit with before making the decision.
Sources
NHS: Weight loss surgery. NICE: Obesity: identification, assessment and management (NG238). British Obesity and Metabolic Surgery Society (BOMSS): Sleeve gastrectomy information for patients.
About this content
This blog is written by James and Kirsten, a couple from the UK who had gastric sleeve surgery together in March 2024.
We started this blog because we couldn't find any sources of content that details before surgery, the surgery and then life post surgery - so we decided to write one ourselves.
Everything on this site is based on our own experience and the research we have done along the way. It is not medical advice. Gastric sleeve surgery is a serious procedure and every patient's journey is different. Please always consult your own bariatric team or GP before making any decisions about your health or treatment.
Some posts on this site may contain featured or sponsored content, or affiliate links. Where this is the case, it will always be clearly stated at the top of the article. Our opinions are always our own.
Publish Date: 17 May 2026 | Last Reviewed: 7 June 2026 | Next Planned Review: 7 December 2027