Bariatric surgery is a powerful intervention for people living with obesity. While most patients focus on weight loss, the benefits of surgery extend far beyond the number on the scale. Improvements in blood pressure, blood sugar, sleep apnoea, joint pain, and fatty liver disease are among the many positive health outcomes.
But as with any medical intervention, it's important to set realistic expectations — especially when it comes to how much weight you might lose. This guide is designed to help you reflect on your personal goals, compare them with current evidence, and start planning for long-term success.
Step 1: Establish Your Starting Point
Please record your height and baseline weight. You will use these later to calculate estimated weight loss based on the type of bariatric surgery you're considering.
Your baseline weight is the weight you had before starting any kind of weight loss effort, such as a diet, medication, or pre-surgery program.
This is the number used to calculate your total weight loss after bariatric surgery. It includes all the weight you lose throughout the entire process, not just after the operation.
If you began a supervised diet or took weight loss medication before surgery, your baseline weight is still the weight you were before those treatments began.
Step 2: Define Your Personal Weight Goals
Everyone comes into bariatric surgery with different expectations. Some people dream of returning to the weight they were in their twenties. Others just want to be able to walk without pain or sleep through the night.
To help guide your thinking, we encourage you to write down your weight goals using four categories. These aren’t just numbers — they’re reflections of how you see your health, your body, and your future.
Take a moment now to grab a piece of paper and write down your: dream weight, happy weight, acceptable weight, and disappointed weight. This will help you clearly understand your expectations before moving forward.
🔵 Dream Weight
“Dream weight" is the ideal weight someone envisions if they could achieve any weight they desired.”
This is your ideal weight — the number you’d choose if there were no limitations. It might be the lowest adult weight you’ve ever had, or simply a weight you associate with confidence and ease. This goal may or may not be medically realistic, but it can be a helpful starting point.
🟢 Happy Weight
“Happy weight" is a weight a person would be content to maintain, though not as ideal as their "dream weight"”
This is a weight where you feel healthier, more mobile, and confident in your own skin — even if it’s not your lowest possible weight. It’s often a realistic, sustainable goal that you could maintain long-term with reasonable effort.
🟡 Acceptable Weight
“A weight that you would not be particularly happy with, but one that you could accept.”
Your acceptable weight is a compromise between aspiration and reality. It’s where you’d still notice real health improvements — like reduced medications or less joint pain — even if it doesn’t match your personal ideal.
🔴 Disappointed Weight
“You would feel disappointed if this were your final weight after surgery.”
This is the weight where you might feel the surgery didn’t meet your expectations.
Once you’ve jotted down your answers, keep them handy. In the next step, you’ll see what the evidence tells us about average weight loss after different types of bariatric surgery — and how your goals compare.
Step 3: Evidence-Based Weight Loss Expectations
Bariatric surgery outcomes are typically expressed as percentage of total weight loss (%TWL). This refers to the amount of your starting body weight that is lost after surgery. Current research indicates the following averages:
- Sleeve Gastrectomy (SG): 20–30% TWL
- Roux-en-Y Gastric Bypass (RYGB): 25–35% TWL
- One Anastomosis Gastric Bypass (OAGB): 27-37% TWL
These figures are based on large studies of patients one to two years post-surgery.
While some patients do lose more than the average amount of weight after surgery, these outcomes are less common. It's natural to believe we might be among those who do exceptionally well, but it's important to remember that the average results are based on large groups of real patients over time. These averages represent successful outcomes for most people. If you achieve a typical result for your procedure, that is still something to be proud of. It means the surgery has worked as expected and is helping to improve your health.
Step 4: Compare Your Goals to What’s Realistic
Now that you know the typical weight loss expected from different types of bariatric surgery, it’s time to compare those outcomes with your personal weight goals.
Most people lose between 20% and 37% of their starting weight, depending on the procedure and individual factors. This means your dream, happy, or acceptable weight might or might not fall within that expected range. That’s important to understand.
🔵 Dream Weight
If your dream weight is lower than what is usually achieved with surgery, it may not be impossible, but it is less likely. It can still be helpful to name this goal, but understand that reaching it might require additional treatment or long-term lifestyle changes.
🟢 Happy Weight
If your happy weight is within the typical range of total weight loss for your surgery, that’s a good sign. It suggests your expectations are realistic and achievable with consistent effort and follow-up care.
🟡 Acceptable Weight
If your acceptable weight is at or just above the average result, that’s a healthy and flexible mindset. Many people feel satisfied here because they experience meaningful improvements in health and quality of life.
🔴 Disappointed Weight
If your disappointed weight is lower than the typical outcome for the surgery you are considering, that means your expectations are not realistic.
For example, if you currently weigh 130 kg and say you would be disappointed unless you weigh less than 70 kg, you are expecting more than 45 percent total weight loss. This is not typical for any bariatric procedure and may not be achievable, even with excellent adherence to lifestyle changes.
What this means
If you believe the surgery will be a failure unless you reach a weight that most patients do not reach, it is important to pause and re-evaluate your goals. We advise patients to postpone surgery until their expectations align with typical outcomes. Not because you don’t deserve extraordinary results, but because lasting success requires realistic expectations.
Undergoing surgery with unrealistic expectations can lead to dissatisfaction, anxiety, and poor long-term outcomes, even when the surgery itself is successful. Your mindset and goals play a key role in your long-term success.
What to do next
- Talk to your bariatric team about your goals.
- Consider adjusting your weight targets based on the average outcomes of your surgery type.
- Focus on the improvements in health, energy, and quality of life that are likely to come with even moderate weight loss.
Bariatric surgery can be life-changing, but only when you are prepared to work with what it can actually deliver. Accepting realistic outcomes is an essential part of preparing for a safe and successful journey.
Step 5: Success is About More Than Just Weight
Even a 10–15% weight loss can result in major health benefits, including:
- Improved blood pressure and cholesterol
- Reduced blood sugar and medication needs for type 2 diabetes
- Resolution or improvement of sleep apnoea
- Less joint pain and improved mobility
- Better liver function
- Improved fertility and hormonal balance
It’s also normal to regain 5–10% of your body weight after the initial period of weight loss. This is part of your body’s long-term stabilisation and does not indicate failure.
Final Thoughts
Setting realistic goals is a key part of preparing for bariatric surgery. While weight loss is important, the broader impact on your health, quality of life, and daily functioning is equally — if not more — significant.
Use this guide as a personal reflection tool and bring it to your next appointment to discuss your goals with your surgical team.
Bariatric surgery is not about chasing perfection — it’s about achieving better health and sustaining it over time.
