Gastric sleeve surgery is an evidence-based bariatric procedure that helps obese patients achieve drastic weight loss by removing a large portion of the stomach. The results for gastric sleeve surgery speak for themselves — according to the American Society for Metabolic and Bariatric Surgery (ASMBS), the average sleeve gastrectomy patient will lose up to 60–70% of excess weight within 12 to 18 months.
However, as with everything, weight loss results can vary from patient to patient. Let’s look at the average monthly weight loss after gastric sleeve surgery, as well as the factors that contribute to maintaining weight loss or regaining lost weight in the years following gastric sleeve surgery.
Post-Gastric Sleeve Monthly Weight Loss
The rate of weight loss varies for each patient — prevailing physical conditions, compliance with nutritional guidelines, and lifestyle changes all play a part in determining effective weight loss. On average, patients will lose between 3.5 kg and 7 kg per month after gastric sleeve surgery. The most weight loss will occur in the first 1-2 months, stabilising over the next 18 months.
First month post-surgery
In the first month following gastric sleeve surgery, patients typically lose about a tenth of their overall body weight (9.7%, according to a 2014 study by the Brazilian Archives of Digestive Surgery). For a patient weighing in at 150 kg, the expected weight loss in the first month would be approximately 15 kg. This is largely the result of the sudden removal and reduction of 70-85% of the stomach’s capacity. But most of this weight loss will be fluids, not fat.
3 months
At the 3-month mark, weight loss will begin to stabilise to ~4 to 6 kilograms per month. A 2022 study published in Surgical Endoscopy found that patients had lost about 25–30% of excess weight after three months post-surgery.
6 months
6 months post surgery, patients will experience weight loss at a slower rate than those first few initial months. A patient initially weighing in at 130 kg would have lost approximately 30-45 kg at this stage, translating to significant changes in body size and improvements in obesity-related conditions like diabetes and high blood pressure.
12 months
Twelve months in, most patients will have lost 60–70% of their excess weight. Consistent efforts will typically result in 1.5 kg-2.5 kg of loss each month. Studies show that those who pair the surgery with routine psychological support, food tracking, and consistent exercise are more likely to reach or exceed their goals.
18 months and after
Weight loss at 18 months and beyond is possible for those who continue to focus on healthier eating and living habits. A long-term study by the Annals of Surgery in 2019 revealed that most patients maintain at least 50–60% of their excess weight loss five years post-surgery. Beyond 18 months, continued weight loss depends largely on lifestyle choices, mindset, and how your body responds over time.
Will I Gain Weight After Gastric Sleeve Surgery?
Patients can regain lost weight after gastric sleeve surgery, especially when the recommended dietary and nutritional regimen is not closely followed. A 2013 study published in Gastroenterology Research and Practice showed that gastric sleeve patients may regain 15–25% of lost weight.
This can happen due to grazing (eating small amounts of food many times during the day), choosing high-calorie foods, or emotional eating, which causes the stomach to expand, undoing some of the surgery’s effectiveness.
It’s normal to face challenges with cravings or engaging in past eating behaviours; but it’s important to remember that nutritionists' and doctors' recommendations are carefully tailored to ensure effective weight loss. For the best results, stick to the prescribed regimen as closely as possible and make sure you’ve got the right support.
Maintaining Weight Loss From Gastric Sleeve
Those first few months of dramatic weight loss can be both encouraging and surprising - but it’s important to not let complacency set in. Long term weight loss will only be achieved with a long term approach. Instead of viewing gastric sleeve surgery as a quick-fix solution to get your body weight under control, think of surgery as the starting point (not the finish line!) for a healthier, more sustainable lifestyle. By making a lifelong commitment to eating healthier, being more active, and managing your appetite, you can maximise the weight loss benefits of gastric sleeve surgery.
At Central Coast Surgery, Dr Ken Wong offers gastric sleeve surgery that achieves lasting weight loss. As the leading weight loss surgery clinic on the Central Coast, we have a team of nutritionists and experts to help you achieve your desired weight loss and health goals.