Gastric Surgery Weight loss – what to expect when you’re expecting to lose

June 11, 2019 10:45 pm

We have to start by ensuring you understand the goal of weight loss surgery.

The objective is to reach and maintain a healthy weight for the long term.  Gastric surgery isn’t a ‘fast weight loss’ miracle cure, although the weight loss can be fast and it can cure many issues you are facing – getting your head around the fact that if you do this right with the aid of the tool, you will NEVER have to face obesity again. To do this, you need to understand the first 18 months post gastric surgery!

A lot of clients ask about the weight loss progression and tend to get stressed when the dreaded ‘stall’ or plateau occurs.  Getting stressed about stalls after gastric surgery is like

…trying to find a black cat in a dark room. Especially if there is no cat (Confucius).

When we hear stressed calls or emails or posts about stalls – we immediately know that person just hasn’t got it yet.  They are still thinking this is a miracle cure, a shortcut to weightloss, a quick and easy way to lose weight and not, in fact, a journey.  A journey of discovery, a journey of life change.   Time for some hard truths!

What are you expecting?

If you are expecting to lose all your weight in 12 months – then no. It’s not going to happen!  First of all, you need to have a healthy view of what your ideal weight is.  Using a BMI calculator and adjusting for your frame size, you should have an ideal weight in the healthy range.  This will give you a good idea of how much weight you need to lose.

Then.. think about every diet you have been on and how successful it was.  The air diet you embarked on.. sure you lost 10kg in 9 days, but you put back on 14kg.  Then there was the mushroom diet, the tapeworm diet, the cotton ball diet, the vinegar diet.. all resulted in you losing weight, then putting it back on.. otherwise you wouldn’t be here.  Think about how you FELT during those diets. Hungry, cranky, tired, depressed are usually the words that accompany diets. That’s because literally the word DIET means a ‘temporary change’.  You can’t keep it up!

Gastric surgery IS NOT A DIET!  It’s a TOOL designed to give you back control over a body and mind that you have lost control of.  But if you go into this with the same diet head on, you are not going to have a good time, you are not going to be successful long term.

Setting healthy expectations

Weight loss post gastric surgery is all about the ‘averages’.   Over an 18 month period, one should expect to lose up to 80% of the excess body weight. The average loss for most patients is 60% of excess weight which depending on your starting weight, is still a LOT of weight!

So, if you have 50kg of excess weight, you can expect to lose up to 40kg.  Some will lose less, some will lose more.

Your gender, starting weight, height, genetics, pre-surgery health, hormones, food choices post surgery, drink choices post surgery and exercise will all play a part.

Weight loss timeline post gastric surgery

First 2 weeks

First-month post gastric surgery is a mix of excitement, change and adjustment for most.  Set aside the discomfort of the surgery, a huge loss usually occurs in the first month. Sometimes, clients have lost 10kg before coming home!  It is important to understand this is mostly fluid in the first 14 days.  It’s still weight that needs to go! Fluid retention accounts for 2.5kg to 5kg of your excess weight.

14 days to up to 3 months

This time period incorporates the healing phase – depending on your starting health can be as little as 6 weeks to up to 6 months.

It’s not just about the little scars from surgery and the new stomach healing, the body has just undergone a huge change.   Our bodies are a single unit made up of thousands of systems all working together and you’ve just upset the apple cart! But because our bodies are incredibly designed – it adjusts, it compensates and it processes the new norms quickly in most cases, but slowly in others.

Your neural pathways, the way the brain processes this new stomach, hormone adjustments, (to name a few) are all adjusting, or healing.

During this healing phase, you will NOT be losing a lot of fat.  Bottom line, you will still be losing a lot of fluid and also muscle.   Why? The body is a survival machine and after the standard 6 weeks of not doing anything too strenuous, the body will continue to shed muscle as the body wants to retain the fat as it doesn’t see it as bad.  Muscle is seen as ‘excess to requirements’ as you probably don’t use them too much at this stage and it is much easier to process and is a dense energy source.

Don’t despair, you will lose some fat, your clothes will start to feel looser and you will have a LOT of energy (or at least days of high energy improving over time)  That’s the plus side.

You should expect to have lost anywhere from 25-30% of your excess body weight by the end of 3 months.

Tips for this period

  • Start walking!  Even if it’s just 5-10 minutes at a time. Build it up to a daily routine of 30+ minutes.  (Talk to your GP before starting any exercise program)
  • Try different foods to see what you can tolerate. Always keep in mind – Protein first! If your body rejects the new food – then don’t give up, try again in a month or two.  Taste buds are changing, the body may not quite be ready for it.
  • Use a SMALL plate. Don’t set yourself up for mental failure. Using a big plate and only eating a few tablespoons (if that) can be disheartening. Using a small plate helps your brain adjust to the new norms. It’s probably used to seeing a plate piled high, so retrain your brain! Remember that eating is still enjoyable, it’s now about the taste, the senses and not eating enough for 4 people!


3-6 months

Weight loss timeline post gastric surgery

Now, the exciting times begin!  The body says “Hang on!”, this girl is serious!  This is the LONGEST she has ever stuck to a diet!  (alarm sounds in the background)

Your body starts to understand that this new caloric deficit is here to stay and it incredibly flips a switch and turns to the freezer of fat!  Yay!

And doesn’t it what!

By the end of 6 months, you would have lost a lot of weight.  Up to 50% of your excess body weight. So, if you have 60kg of excess weight, you would have lost 30kg! That’s 15 x 2 litre bottles of milk!

22 kg (50 pounds) of fat

Let’s talk about the averages here.

30 kg of loss over 6 months.  5kg a month on average doesn’t sound like a lot but it is considering what you’ve just gone through.

Remember, you’ve had surgery, you’ve gone through a NON-loss healing phase of around 3 months, then the weight loss actually starts – and if you get your head in the game now, exciting times are coming!

The other thing to keep in mind is you’ve done this without the hunger of a traditional starvation diet, you’ve had small meals and felt like you’ve eaten Christmas dinner and you’ve probably lost 2-3 dress/pants sizes already.   You’ve also probably gone through your first 2 stalls and come out the other side.


We just have one.  Stop stressing about it!

If you are honest with yourself, you know whether you’ve been good with nutrition and this could be playing a part, but generally, stalls will last 1-4 weeks at a time.   The body seems to have set levels of fat that it will allow to go without a fight, then once it gets past those levels it fights you.  After all, every diet you have been on you know this to be true.  It’s the moment that the body makes it really hard, you battle the mind and your emotions and if you get through it, you start to lose weight again.  Botom line, the caloric deficit (less calories in that out) mean it’s a mathematical certainty weight loss will start up again.  Defeated by the sleeve and your resolve, the body will adjust and the fat loss show will go on.

Okay, here are some more tips.  Spoiler – there is NO magical button, gimmick or trick.

  • Commit to tracking your food intake.. like.. honestly. Not for sympathy posts. “I only eat a stick of celery but I’m not losing”  Tracking food should be about you holding yourself accountable. So this should be just for you and/or the dietitian. This is to make sure you are aware of what you are eating and drinking. Use an app so it makes it simpler. Track your water intake as well.  If you are honest with yourself, you will start to see potential patterns forming that are damaging.  Not enough protein, not enough water.  You won’t know unless you track.
  • Make sure you are eating enough calories. Go for the target!  We are hard-wired to go into starvation mode and the balance of calories (the right calories) is important even post-bariatric surgery.  If you aren’t eating enough you will feel sluggish at the same time because it’s slowing everything down to conserve energy.
  • Focus on nutritious SOLID foods.  Stay away from drinking your calories. You didn’t go down this journey to end up on Optifast!  Understand the stage you are at, eat protein first but introduce solid dense foods – as your body can handle them.  Soft foods or liquid foods are too easily ‘slid’ through the stomach – you will be looking too soon for food. Solid foods make your body work, it takes time to digest and process allowing the body to extract maximum nutrition.
  • Add MORE protein to your diet. Nuff said apart from eating protein FIRST and OFTEN! Divide your ideal weight by 2.2. That’s the minimum grams of protein you should be trying to achieve daily.
  • Don’t work out TOO much.  How long is a piece of string?  This is dependent on so many factors. We absolutely recommend seeing an exercise physiologist, one that specialises in rehabilitation, rather than a PT, as they are hell-bent on beating your body into submission, but it won’t work for you at this early stage on the calories you are on – it will have the opposite effect.
  • Don’t NOT work out at all.  You need to exercise!  Whether it’s a low-intensity walk or even lifting weights to preserve and build lean muscle mass – as tempting as it is to lounge on the couch after surgery – get off your behind!  As per above, you should seek help if you’ve never exercised before. Start with your GP and then get a referral to an exercise physiologist. If you have been an avid exerciser in the past, time to crack out those leg warmers!
  • Get off the bloody scales!  Weighing yourself every day will only cause stress if things haven’t moved. We’ve known some patients who weigh themselves 4 times a day!  Talk about setting up for failure!  Your period (for females) hormones, water, the weather can all play a part in what you see on the scales on a day-to-day basis. . We recommend cracking the tape measure out instead of the scales during a stall. Seeing a drop in the tape in key areas like the waist, upper thighs, neck, chest etc will demonstrate that something is happening, it’s just not being reflected on the evil evil scales.  During a stall, weigh yourself weekly – the weight loss will catch up the tape! We promise!

I am still stalling


If after you have done these things you are still stalling – please get in touch with the dietitian – but be prepared, the first thing you are going to be asked to do is to keep a food diary.

6-12 months

Weight loss timeline post gastric surgery

Oh boy.  Here come the goals being knocked down!   By the end of this 12 months – that’s only 365 days you should have lost between 50%-65% of your excess body weight.

60kg to lose = 39kg. Remember, what 22kg of fat looks like. You can almost double that!

44 kg fat (100 pounds)

By now, you are in the range of ‘normal’ sized clothes, (shopping in the ‘normal’ sizes is a good benchmark)  you feel good about yourself, you are a serial Instagram or Facebook poster of your new bod, you are getting comments from everyone who knows, your significant other can’t keep their hands off you or you are starting to feel sexy as a single – getting ready to mingle.  At this stage, you are stepping out of your old obese mind and at this stage the journey should be about enjoyment, not stressing over the scales.

Weight loss will be slowing down now (more on this soon) but that’s ok.  In our experience, this is the magical part of the journey.  Eating is now normalised, you know what to do and not what to do.  Your family has adjusted, your friends understand what’s going on. You’re probably (hopefully) exercising which means because muscle weighs more than fat, you are actually still losing fat, but the scales aren’t dropping at the rate it was 3 months ago.

All in all – you feel pretty darned good.  Stalls – so what!

Tips for 12 months and beyond

  • Don’t get complacent – stay away from slider foods – keep being religious about protein. It should be second nature by now.
  • Alcohol is tempting, but there are studies that show a high rate of alcoholism in post-bariatric patients. Alcohol can be pure empty calories that can slow down your weight loss.  Especially if you are a mixer. That is; mixing Vodka or Gin or whatever with a sugary drink.  Be aware!
  • Don’t overdo it with portion sizes.  You still should be using a portion control plate and thinking about every mouthful.
  • Enjoy it!  You are amazing and you’ve been on your New Life journey for a year. Happy birthday 😊


12 months to 18 months

Weight loss timeline post gastric surgery

Ok, so the weight loss will slow during this period. Why? Simple physics.

Our bodies require X amount of calories to function.  Calories is the energy measurement of the input and output of the body.  This is called our BMR or Basal Metabolic Rate.  If you sat on the couch and literally did nothing, your body requires X number of calories to power your systems. Think about a car sitting and just idling – the car uses a minimal amount of fuel while idling until it’s put in gear and the engine starts revving. BMR is the car sitting and idling.

As you’ve gotten smaller, your BMR has also gotten smaller.  That is; the smaller you are, the less your body needs in caloric output to keep its systems functioning.

It takes about 7000 calorie deficit (less calories in than out) to burn nearly 1kg of fat. That deficit can be over 4 days, a week or whatever time frame. But a deficit is required.

Basal Energy Expenditure (BMR)


  • If you were 140 kg, 35 years of age, 165cm tall, your body required 2136 calories per day to function without any activity.
  • A year later, you are 36, 100kg, still 165cm tall but now only require 1748 calories per day if you did nothing.
  • At the start you if you consumed 900 calories per day, you had a 1236 calorie per day deficit meaning you would lose 1kg of fat every 3 days.
  • Now your BMR is 1748 calories, and if you are still only consuming 900 calories per day it means you now have an 848 calorie deficit per day meaning to lose 1kg, you are now waiting close to 9 days.

The big IF is whether you are still only consuming 900 calories per day!  Most patients by this stage are consuming anywhere from 1100 to 1500 calories per day by this stage.

At the top end of 1500 calories per day, it means that 1kg fat loss will take approximately a month if you did nothing but sit on the couch.

What can you do to speed this up?

Well, firstly, 1kg a month when you have already lost 70% of your excess body weight is ok. You can relax and let it happen over time, or you can:

  • Exercise more!  Increasing your energy expenditure increases the gap between input and output.
  • The right exercise.  Doing weights adds lean muscle mass which can increase your metabolism, make you look good and also combat joint and muscular problems
  • Focus again on what you are eating. Yes, generally after 12 months, the razor focus on the prior 12 months is dwindling.  Get that app out again and start tracking.
  • Reset the mind.  Don’t be satisfied until you’ve reached your goal!
  • Get more sleep!  Sleep is the great companion of weight loss.  Get at least 8 hours of quality sleep.

By the end of the 18 months, you should have lost up to 80% of your excess body weight. That’s an incredible result.

Beyond 18 months

This is where you decide whether the sleeve is your life long friend or just another notch on the diet journey.  Your food intake as the stomach has stretched again will allow you to take in more and more calories.  If you don’t keep this in check, you will end up putting on weight again.

Ghrelin (the hunger hormone) will be being reproduced and you will feel hungry more often.

Hopefully, by this stage, you have used the tool and trained yourself, changed your habits, incorporated exericse and movement, changed your lifestyle and swapped out your obese mind for a healthy one!

The sleeve has done its job and will continue to but from here on in, it’s up to you!

    Why wait? Request a FREE quote

    Get a quote now