Weight loss after bariatric surgery

Decrease in body weight after bariatric surgery is usually expressed as a percentage of excess weight loss. Long-term (more than five years) excess weight loss is usually 65-70% following bypass surgery, and 60-65% following gastric sleeve surgery.

Example: a patient whose ideal weight would be 70 kg weighs 130 kg upon admission for surgery. It means that their excess weight is 60 kg. Five years after bypass surgery their expected weight loss is approximately 40 kg, or two-thirds (2/3) of their excess weight (60 kg excess weight). The ideal weight is usually calculated on the basis of a body mass index of 25 kg/m2.

You can calculate your ideal weight by multiplying the square of your height in meters and multiply it by 25. For example, for a person with a height of 1.8 m: (1.8×1.8)x25=81 kg.

Weight loss immediately after surgery may be very rapid, up to 25 kg in the first month in men. This rapid weight loss lasts for up to six months. After that, the weight loss slows down, but it still lasts for approximately one year. 1.5-2 years after surgery patients achieve their lowest (postoperative) body weight, having lost 75-80% of their excess weight. Usually this result is not sustainable, and the majority of patients regain 5-10 kg, after which their weight stabilises. Thus, some weight gain during this period is considered to be normal and expected. Long-term weight loss, as stated previously, is 60-70% of the excess weight. Regardless of the type of surgery, the risk for weight gain persists throughout the individual’s life. In the long term, up to 70% of patients slowly gain weight over the years, yet despite this, significant weight loss (more than 50% of their excess weight) persists throughout life in the majority (80-90%) of patients.

Postoperative weight gain can be caused by:

• Ignoring dietary recommendations
• Gastric dilation, which results in more calories being consumed. This can also be related to continuing to eat after satiety has been achieved, either as consolation, pastime, or under the influence of alcohol.
• Alcohol abuse
• Lack of physical activity
• Certain medicinal products

Important! Follow the dietary recommendations and lead a physically active lifestyle in order to maintain your body weight decrease, to improve your health condition, and to prevent weight gain.

In 2015 we conducted a follow-up study in patients who underwent surgery in 2005-2009; the time from surgery was at least five years. After bypass surgery their average weight loss was 68% of their excess weight, which is comparable to data published in international medical literature.

Weight stalls

Almost all patients will have periods within one year from the surgery (during which their weight should decrease steadily) when their weight does not change. This can last for days and weeks. The human body retains the highest value of weight during your previous lifetime in its “memory” and strives to maintain it. This is comparable to a situation when a thermostat has been set to an abnormally high temperature. Our body has approximately 10 different and effective ways for regulating and maintaining body weight. After bariatric surgery the body is forced to regulate this metaphorical weight thermostat to “cooler” or, in terms of weight, lower. All this does not happen at once and the body will experiment with different balance states, trying to maintain them temporarily, and thus contributing to stable weight. This is a normal and transient phenomenon not to be worried about. With some time, weight starts to decrease again.

Important! Temporary weight stalls does not indicate treatment failure or insufficient weight loss in the future.


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