One of the major fears associated with weight loss surgery is weight regain after the surgery – weight regain after bariatric surgery can be intimidating and upsetting, which is why it is important to have realistic expectations when it comes to weight loss and its permanence. It is also important to understand which behavioural choices will allow you to maintain the initial weight loss in the long term and prevent weight regain.

Weight loss is rapid during the first 2–3 months after the surgery, but slows down later. The lowest weight is reached around 9–12 months post-surgery. By this time, around 70–80%, and sometimes even 100%, of the excess weight will be lost.

However, after the initial weight loss, some weight gain is expected and the amount of weight gained depends on the individual. It is normal and expected that most patients will then gain 5–10 kg and the weight will stabilize at a level where patients have lost 60–70% of their excess weight.

For example: For a patient whose weight prior to surgery is 130 kg, the ideal weight is 70 kg (i.e. the patient is 60 kg overweight), they lose 50 kg by the end of the first year post-surgery, during the second year post-surgery they gain 10 kg and the weight stabilizes at 90 kg. The patient has then lost 2/3 or 67% or 40 kg of their excess weight. The outcome of the treatment meets the expectations, although the patient might be somewhat disappointed to find that the weight loss of 50 kg was not maintained.

Long-term results of bariatric surgery

Several studies regarding the long-term efficacy of bariatric surgery have been published. For example, a review(1) of 87 single-subject research papers found that 10 years after gastric bypass surgery the patients had, on average, lost 64% of their excess weight and 53% after sleeve gastrectomy only 3.4% of the patients had gained so much weight after 10 years that their weight was within ±5% of the weight they had prior to surgery(2).

A study of Estonian patients that examined the long-term results after sleeve gastrectomy found that patients had on average lost 61% of their excess weight seven years post-surgery(3).

During the 10 years after surgery, 25–30% of patients will experience weight gain which can be upsetting and impair their quality of life. It is important to note that despite the weight gain, these patients still maintain a significant level of weight loss compared to their weight prior to surgery. 

(1)Golzarand, M., Toolabi, K. & Farid, R. Surg Endosc (2017) 31: 4331.
(2)Maciejewski ML, Arterburn DE, Van Scoyoc L, et al. Bariatric Surgery and Long-term Durability of Weight Loss. JAMA Surg. 2016;151(11):1046-1055
(3)Five-Year Outcome of Laparoscopic Sleeve Gastrectomy, Resolution of Comorbidities, and Risk for Cumulative Nutritional Deficiencies.
Scand J Surg. 2019 Mar;108(1).

Individual weight changes following bariatric surgery can differ significantly from the average

Long-term studies conducted in different countries demonstrate that 10 years after surgery the average patient does well, maintaining 30–40 kg of weight loss. Looking at individual patient treatment outcomes, we have seen that 10–15% of patients maintain their ideal weight, while 3–4% of them regain the weight they had prior to surgery (or more). The rest fall between these two extremes.

The surgery itself rarely fails technically. The techniques are standard and the large number of surgeries performed annually (more than 300 at Bariatric Services AS) allows us to maintain and further develop good surgical practice. However, each patient’s body and metabolism reacts differently to the surgery. Both age and genes play a role here and this is something we cannot change.

Long-term weight loss with different surgical methods (standard and mini gastric bypass, sleeve gastrectomy) appears to provide an advantage to bypassing surgeries – standard and mini gastric bypass – although the differences are not huge. When it comes to gastric bypass surgery, the outcome is easier to predict, while in the case of sleeve gastrectomy, the differences between patients are greater.

How can I maintain the weight loss?

Leaving aside genes and age as the factors influencing the outcome of the treatment for the moment, let’s take a look at how the lifestyle and behaviour of the so-called “successful” patients who have lost weight differs from that of the “unsuccessful” ones. Studies on this topic highlight four important habits associated with greater and more durable weight loss.

  • Eating behavior and dietary choices. Patients need to understand what their food consists of and avoid heavily processed and semi-prepared foods. The easiest way to achieve this is to cook your own meals from whole ingredients. This is not always possible but even then, your choices should not include street food, convenience food or sweets. All foodstuffs must be of high quality.
  • Physical activity. Regular physical exercise helps you to maintain weight loss, rather than lose weight. Patients who are successful at maintaining their weight loss are physically more active. Purposeful exercise should be done for at least 200 minutes a week and should be spread over at least three sessions.
  • A good nights sleep. Weight loss improves sleep quality and can alleviate sleep disorders (e.g. sleep apnea). The most common causes of sleep problems after bariatric surgery are insufficient sleep and disruption of circadian rhythms (e.g. night shifts), which should be avoided if possible.
  • Positive interest in the well-being of your health and body. Respecting your body, monitoring its weight and condition regularly, going to recommended post-surgery follow-up appointments, participating in age-appropriate screenings (e.g. cervical or breast cancer), vaccinating, not smoking, reasonable risk-taking, etc. For example, a seemingly small activity – weighing yourself weekly – is associated with maintaining weight loss.

Here are some of the most common eating behaviour mistakes associated with weight regain and coping strategies

Chaotic eating – Lacks structure; no formal eating pattern
Create structure, including approximate eating times spaced throughout the day; prioritize eating within the day’s activities

Skipping meals – Going long periods without food, which can result in overeating later
Planning of meals, with suitable snacks or easy options for the individual’s situation

Poor food choices – Highly processed, fried and fast foods; falling back on previous habits that resulted in initial weight gain
Identification of easy food choices with less processing;

Grazing Small portions of food eaten over an extended period of time – previous binge eating may be expressed in this way
Discrete meals of one-cup volume at meal times to ensure satisfaction

Night eating – A significant proportion of calories are ingested after the evening meal
Ensure adequate and even food spacing throughout the day

Excessive portion size – Eating beyond ‘satisfaction’ resulting in ‘fullness’; this continues to drive excessive intakes
Reduce and maintain smaller portion sizes, ideally one-cup volume at meals

Alcohol intake – Alcohol is rapidly absorbed following bariatric surgery, resulting in disinhibited eating and lack of satiety from liquid calories
Limit alcohol intake; alcohol problems can develop after surgery in those who previously experienced no problems and all care team members should be alert

Inadequate protein intake – Protein is important for satiety but also for maintenance of muscle mass, which contributes to resting metabolic rate
Education on protein content of food along with strategies, recipes and ideas for inclusion

Mixing fluids and foods – This may stretch the capacity of the stomach and cause early gastric emptying
Avoid fluids in the immediate pre-meal period and for 30 minutes after

When can the result of the surgery be considered good – when can you be satisfied with it?

Conventionally, the result of bariatric surgery is considered to be good when the patient has lost 50% or more of the excess weight. However, sometimes even a 40% loss of excess weight may mean a weight loss of 40–50 kg (in the case of high initial weight) which might be significantly more than any other alternative weight loss method would allow.

The success of the surgery should not be assessed only in terms of weight loss or regain – the changes in health status and quality of life should also be considered.

A study that examined the impact of gastric bypass surgery on the quality of life two years after the surgery(4) found that the quality of life of 97% of the patients had improved after the surgery.

Examples of positive changes included an overall improvement in physical and mental fitness, increased self-esteem, higher energy levels, reduced physical pain, an improved sex life, more successful social behaviour and improved emotional health.

Satisfaction with the outcome of the surgery starts with setting realistic goals and being aware of your active role in reaching and maintaining the result.



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