One of the biggest questions we had when researching whether gastric sleeve surgery was right for us was: how much weight can you actually expect to lose?
We spent countless hours reading through NHS guidance, bariatric clinic websites, Reddit forums, and weight-loss calculators – and what we found was that the answers varied wildly.
We’re now over two years post-op. This post combines the research we did before surgery with the real numbers from our own journey since. Both of us had surgery in March 2024, so the figures below are not projections – they’re what actually happened.
Understanding how gastric sleeve surgery works
To understand potential weight loss, it helps to know what actually changes after the operation.
During gastric sleeve surgery, around 75-80% of your stomach is permanently removed, leaving a narrow, tube-shaped “sleeve” that holds roughly 150-200ml of food – about the size of a banana.
Because your stomach is smaller, you can only eat small portions. But the surgery also removes most of the part that produces ghrelin, the hunger hormone, meaning you often don’t feel hungry in the same way.
This combination – reduced capacity and reduced appetite – is what makes sustainable weight loss possible.
Before surgery, James could easily finish a full KFC meal. Now, a single mini fillet and a few chips are enough to feel full. The change isn’t just physical – it’s psychological too.
What the research says about weight loss after gastric sleeve
According to published bariatric data, most patients lose around 60-70% of their excess body weight within 12-18 months.
To explain what that means: “excess body weight” refers to the amount above a healthy BMI (24.9). So if your ideal weight is 12 stone and you start at 20 stone, your excess weight is 8 stone. Losing 60-70% of that means losing roughly 5-5.5 stone.
These figures come from the published literature including NHS guidance and the National Bariatric Surgery Registry run by BOMSS. The most authoritative sources are linked at the bottom of this post – we’d encourage reading the primary sources rather than relying on any summary, ours included.
Our real progress
At the time of surgery in March 2024, James weighed just over 30 stone and Kirsten around 18 stone.
By the one-year mark, James had lost over 12 stone (168 pounds). Kirsten had lost 8 stone (112 pounds).
Two years on, both of us are in the maintenance phase. James has continued losing gradually and building muscle; Kirsten has maintained her loss while managing Crohn’s disease, which made the journey different but no less real.
We document this in detail, with photos and monthly weigh-ins, on our Progress Updates pages.
These results are well above the typical averages – not because the surgery worked “better” for us, but because we fully committed to the process. We also know people who had surgery in the same month as us and have only lost 20-30 pounds total two years later. The surgery is the same. The outcomes aren’t. That gap comes down to habits, mindset, and consistency – not the procedure itself.
Typical weight loss timeline
While every journey is unique, here is a general guideline based on medical averages and our own experience.
| Timeframe | Average progress | Our experience |
|---|---|---|
| 0-3 months | 30-40 lbs (2-3 stone) | Both lost over 3 stone – mostly from the drastic calorie drop and early recovery. |
| 6 months | 50% of excess weight lost | We were around 66% by this stage thanks to strict routines and regular walking. |
| 12 months | 60-70% of excess weight lost | James had lost 12 stone, Kirsten 8 – both well above expectations. |
| 18-24 months | Weight stabilisation phase | Transition to maintenance and muscle-building. Loss slows; body composition keeps improving. |
| 2+ years | Long-term maintenance | Focus shifts from losing weight to sustaining health. Nutritional vigilance remains essential. |
Weight loss naturally slows over time as your metabolism adapts and calorie intake gradually increases. This is normal and healthy – not a sign that the surgery is “wearing off.”
What makes the difference
Mindset before surgery. We went into this with clear intentions: not a quick fix but a lifelong health reset. Before surgery, we spent months researching, preparing mentally, and planning how we’d handle food addiction, meal preparation, and cravings. That mental preparation mattered when things got hard.
Commitment to lifestyle change. After surgery, everything changes – how you eat, drink, socialise, and think about food. If you try to return to old habits (grazing, takeaways, sugary drinks), the sleeve won’t protect you long-term. We’ve seen this in support groups. Some people simply couldn’t break those habits, and their results reflect that.
Exercise and movement. James started walking daily just a week post-op, eventually progressing to gym workouts and, later, a bodybuilding competition. Kirsten focused on gentle walking due to Crohn’s complications – proving that progress doesn’t require a gym membership, just consistency.
Supplements and hydration. This is crucial and often underestimated. James hit a wall around month 11 – fatigue, brain fog, cold intolerance – caused by nutritional deficiencies. Once we overhauled the supplement protocol, everything improved: energy, mood, and recovery. We’ve written about this in detail on our supplements and vitamins page.
Maintaining the results
Two years on, long-term success comes from a few consistent practices: listening to your body rather than chasing numbers; planning meals and prep to stay accountable; regular check-ins with weight, measurements, or progress photos; staying hydrated and supplementing properly; and having support – whether a partner, bariatric group, or online community.
The restriction from the sleeve does ease over time. That’s not the surgery failing. It’s the body healing and adapting. The habits you build in year one are what carry you through year two, five, and beyond.
The bottom line
Gastric sleeve surgery is one of the most effective weight-loss tools available, but the results are not guaranteed. They require the right mindset, preparation, and daily discipline – applied consistently over years, not just months.
If you treat the sleeve as a tool rather than a cure, the results can be transformative. We’ve lived it. Two years later, both of us are healthier than we’ve been in our adult lives.
If you’re at the start of this, we hope our numbers give you a realistic picture – and our experience gives you some honest preparation for what it actually takes.
Sources cited in this post: Welbourn R et al. – Laparoscopic sleeve gastrectomy: a systematic review (Annals of Surgery, 2019)
BOMSS – National Bariatric Surgery Registry: annual outcomes report (bomss.org)
NICE CG189 – Obesity: identification, assessment and management
NHS – Weight loss surgery: benefits
- NHS, “Weight loss surgery”: https://www.nhs.uk/conditions/weight-loss-surgery/
- NICE clinical guideline CG189, “Obesity: identification, assessment and management”: https://www.nice.org.uk/guidance/cg189
- British Obesity & Metabolic Surgery Society (BOMSS), including the National Bariatric Surgery Registry: https://bomss.org/
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: 19 August 2024 | Last Reviewed: 27 June 2026 | Next Planned Review: 27 December 2027