long-term outcomes

Long-Term Outcomes Following Bariatric Surgery

September 21, 2020

Long-Term Outcomes Following Bariatric Surgery

For severe obesity, bariatric surgery has been found to be the most effective form of treatment. This is largely due to the fact that the outcomes from bariatric surgery results in significant and sustained weight loss, as well as the reduction of obesity-related co-morbidities. Let's take a look at the long-term outcomes following bariatric surgery!

After bariatric surgery, weight loss remains a primary outcome of interest for the long-term. Bariatric surgeons have been able to adapt to improve weight loss outcomes by acquiring more experience and refinements in minimally invasive techniques.

Individuals affected by severe obesity are resistant to long-term weight-loss by diet and exercise. The National Institutes of Health Experts Panel recognize that ‘long-term’ weight-loss is nearly impossible for those affected by severe obesity without the assistance of a metabolic surgical procedure.

Long-Term Outcomes Following Bariatric Surgery Are Effective

Bariatric surgeries are effective because these procedures offset certain conditions caused by dieting that are responsible for rapid and efficient weight regain following dieting.

When a person loses weight, energy expenditure (the number of calories the body burns) is reduced. With diet, energy expenditure at rest and with activity is reduced to a greater extent than can be explained by changes in body size or composition (amount of lean and fat tissue).

At the same time, appetite regulation is altered following a diet, increasing hunger and the desire to eat. Therefore, there are significant biological differences between someone who has lost weight by diet and someone of the same size and body composition to that of an individual who has never lost weight.

For example, the body of an individual who reduces their weight from 200 to 170 pounds burns fewer calories than the body of someone weighing 170 pounds and has never been on a diet. This means that, in order to maintain weight-loss, the person who has been on a diet will have to eat fewer calories than someone who naturally weighs the same.

In contrast to dieting, weight-loss following bariatric surgery does not reduce energy expenditure or the amount of calories the body burns to levels greater than predicted by changes in body weight and composition. In fact, some studies even find that certain operations even may increase energy expenditure.

In addition, some bariatric procedures, unlike dieting, also cause biological changes that help reduce energy intake (food, beverage). A decrease in energy intake with surgery results from anatomical changes to the stomach or gut that restrict food intake or cause malabsorption of nutrients.

In addition, bariatric surgery increases the production of certain gut hormones that interact with the brain to reduce hunger, decrease appetite, and enhance satiety (feelings of fullness). In these ways, bariatric and metabolic surgery, unlike dieting, produces long-term weight-loss.

Bariatric surgeries can lead to deficiencies in vitamins and minerals by reducing nutrient intake or by causing reduced absorption from the intestine. Bariatric operations vary in the extent of malabsorption and they may cause, and vary in which nutrients may be affected.

The more malabsorptive bariatric procedures also increase the risk of protein deficiency. Deficiencies in micronutrients and protein can adversely affect health, causing fatigue, anemia, bone and muscle loss, impaired night vision, low immunity, loss of appropriate nerve function, and even cognitive defects.

Fortunately, nutrient deficiencies following surgery can be avoided with an appropriate diet and the use of dietary supplements, i.e. vitamins, minerals, and, in some cases, protein supplements. Nutrient guidelines for different types of bariatric surgery procedures have been established by the ASMBS Nutritional Experts Committee and published in the journal, Surgery for Obesity and Other Related Disorders.

Before and after surgery, patients are advised of their dietary and supplement needs and followed by a nutritionist with bariatric expertise. Most bariatric programs also require patients to have their vitamins and minerals checked on a regular basis following surgery.

Nutrient deficiencies and any associated health issues are preventable with patient monitoring and patient compliance in following dietary and supplement (vitamin and mineral) recommendations. Health problems due to deficiencies usually occur in patients who do not regularly follow-up with their surgeon to establish healthy nutrient levels.

Weight Regain After Bariatric Surgery

Recidivism of weight loss after bariatric surgery is a concern among many, especially several years after the primary procedure. The expected weight loss at 2.5 years will decline over time, however, it is important to note that such maintenance of weight loss over a decade after surgery should be considered a relatively major success. Both weight loss and non-weight-loss outcomes appear to be improved after bariatric surgery compared to their pre-surgery values.

Longitudinal studies find that most bariatric surgery patients maintain successful weight-loss long-term. ‘Successful’ weight-loss is arbitrarily defined as weight-loss equal to or greater than 50 percent of excess body weight.

Often, successful results are determined by the patient, and by their perceived improvement in the quality of their life. In such cases, the total retained weight-loss may be more, or less, than this arbitrary definition. Such massive and sustained weight reduction with surgery is in sharp contrast to the experience most patients have previously had with non-surgical therapies.

Long-Term Outcomes of Co-Morbidities and Mortality

Several large population studies find that individuals affected by severe obesity who have had bariatric surgery have a lower risk of death than individuals affected by obesity who do not have surgery.

One of these studies found up to an 89 percent greater reduction in mortality throughout a 5-year observation period for individuals who had bariatric surgery when compared to those who did not.

Another large population study comparing mortality rates of bariatric and non-bariatric patients found a greater than 90 percent reduction in death associated with diabetes and a greater than 50 percent reduction in death from heart disease. The mortality rate for bariatric surgery (3 out of 1000) is similar to that of a gallbladder removal and considerably less than that of a hip replacement.

The exceptionally low mortality rate with bariatric surgery is quite remarkable, considering that most patients affected by severe obesity are in poor health and have one or more life-threatening diseases at the time of their surgery.

Therefore, as regards to mortality, the benefits of surgery far exceed the risks.

The exceptionally high reduction in mortality rates with bariatric surgery is due to the highly significant improvement in those diseases that are caused or worsened by obesity. Bariatric surgery is associated with massive weight-loss and improves, or even resolves, obesity-related co-morbidities for the majority of patients.

These co-morbidities include high blood pressure, sleep apnea, asthma and other obesity-related breathing disorders, arthritis, lipid (cholesterol) abnormalities, gastroesophageal reflux disease, fatty liver disease, venous stasis, urinary stress incontinence, pseudotumor cerebri, and more. Bariatric surgeries also lead to improvement and remission of Type II diabetes mellitus (T2DM).

In the past, diabetes was considered to be a progressive and incurable disease. Treatments include weight loss and lifestyle changes for those who are overweight or obese and anti-diabetic medication, including insulin. These treatments help to control T2DM but rarely cause remission of the disease. However, there is now a large body of scientific evidence showing remission of T2DM following bariatric surgery.

A large review of 621 studies involving 135,247 patients found that bariatric surgery causes improvement of diabetes in more than 85 percent of the diabetic population and remission of the disease in 78 percent.

Remission of T2DM was highest for the biliopancreatic diversion with duodenal switch (BPD/DS) with a remission rate of 95 percent, followed by the Roux-en-Y gastric bypass (RYGB) with remission in 80 percent of patients, and the adjustable gastric band (AGB) with a remission rate of 60 percent.

Other studies comparing remission of diabetes between surgeries found comparable rates between the laparoscopic sleeve gastrectomy (LSG) and RYGB, i.e. 80 percent. Causes of improvement or remission of diabetes have not been completely identified. Improvement of T2DM with AGB is related to weight loss.

However, with other surgeries, such as the LSG or RYGB, diabetes remission or improvement occurs early after surgery – well before there is significant weight reduction. In fact, some bariatric patients with T2DM leave the hospital with normal blood sugar and without the need for anti-diabetic medication.

Quality of Life as Long-Term Outcomes

In addition to improvements in health and longevity, surgical weight-loss improves overall quality of life. Measures of quality of life that are positively affected by bariatric surgery include physical functions such as mobility, self-esteem, work, social interactions, and sexual function.

Singlehood is significantly reduced, as is unemployment and disability. Furthermore, depression and anxiety are significantly reduced following bariatric surgery.

Finally, it is important to distinguish what obesity is not: it is not a personal choice but a disease. Even though the medical community now recognizes obesity as a disease, 48% of Americans say obesity is mostly a lifestyle choice resulting from a person’s eating and exercise habits.

It’s important to recognize bariatric surgery as a viable tool for long-term weight loss success. Bariatric surgery has been shown to increase lifespan longevity, resolution or improvement of metabolic illness, and better overall quality of life.

It’s important to note that not all people with obesity will be successful after bariatric surgery. However, people with obesity who use this metabolic surgical tool properly will achieve favorable long-term weight loss outcomes.

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patricia cherasard


Dr. Patricia Cherasard is the Chief Physician Assistant for Winthrop Surgical Associates and Bariatric Surgery at NYU Health's NYU Winthrop Hospital. Her role in the perioperative period of our bariatric surgical patient population includes guidance in the preparation for weight loss surgery, helping to attain their weight loss goals, and maintenance of their weight loss as well as improved health outcomes.
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