Metabolic reset: Benefits of bariatric surgery beyond weight loss
March 16, 2023
When a person has obesity, many of the factors that contribute to the excess weight result from a positive-energy balance, which is not as metabolically cheerful as it sounds.
The body stores this extra energy in fat cells, which may be under the skin, inside the belly, or in vital organs such as the liver and pancreas. Excess fat deposits interfere with production and effectiveness of hormones such as leptin, ghrelin, and insulin, which manage how our bodies sense hunger and use calories. This can result in further weight gain that creates inflammation, damages cells throughout the body, and taxes the cardiovascular and metabolic systems.
More than 42% of adults in the U.S. have obesity, and although there is a lot of variability in how a higher body weight may affect the health of individuals, excess body fat can greatly increase the risk for health complications in people with obesity in addition to impacting quality of life.
Obesity increases the risk of many cancers, including breast, uterine, and colon cancer. People with obesity face significantly elevated risks of cardiometabolic diseases, such as:
- Type 2 diabetes
- Heart failure
- Coronary artery disease
- Obstructive sleep apnea
Even patients who have obesity without significant health problems today are at greater risk of developing complications within three to five years.
Bariatric surgery is a safe, effective, and underutilized procedure for treating obesity that can lead to significant improvements in metabolic health. In some instances, it can put Type 2 diabetes and fatty liver disease into remission and significantly reduce the risk of heart disease and many cancers.
Unfortunately, bariatric surgery is often viewed as an extreme weight-loss procedure, even though surgical advances and post-operative care have made it as safe as having your gallbladder removed.
The narrative around bariatric surgery needs to change. It should be more accurately described as a preventive and therapeutic cardiometabolic procedure – one that can reverse or stop health conditions before they ever develop.
How bariatric surgery can reset metabolic health
Bariatric procedures such as sleeve gastrectomy, gastric bypass, and endoscopic sleeve gastroplasty revise the stomach and impact hormonal pathways that influence appetite, feelings of fullness, and blood sugar metabolism. Some of the hormone processes bariatric surgery alters include:
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- Ghrelin: The hormone that signals hunger and stimulates the appetite.
- Growth hormone secretagogue receptor (GHS-R): This receptor stimulates food intake and growth hormone secretion, which promotes storing fat rather than burning it for energy.
- Leptin: This hormone signals satiety (feeling full). Obesity can cause leptin resistance, which may lead to overconsumption of calories.
- Insulin: This hormone manages how the body uses and stores sugar. Excess body fat can cause insulin resistance, which can contribute to further weight gain and Type 2 diabetes.
UT Southwestern’s accredited Bariatric Surgery Program has pioneered and advanced weight-loss surgery for more than two decades, offering all types of bariatric operations – including minimally invasive and robotic procedures.
Our expert bariatric surgeons have performed more than 4,000 operations and have trained more than 100 board-certified surgeons. The team also works closely with subspecialists in cardiology, endocrinology, gastroenterology, plastic surgery, abdominal wall reconstruction, and our Weight Wellness Program to deliver comprehensive care before and after surgery. Many insurance providers only cover bariatric procedures done at centers of excellence like UT Southwestern.
Along with treating obesity, we are also studying its causes and preventive measures to truly understand how to achieve success in sustained, long-term weight loss. In 2022, UTSW was named one of just 13 NIH Nutrition Obesity Research Centers in the U.S. We ensure the latest advancements are accessible to our patients.
Weight loss goals for metabolic health
One of the first questions that usually comes up when discussing bariatric surgery is, “How much weight will I lose?”
It’s important to understand that weight loss varies between people, whether it is from dieting, working out, medications, or surgery. BMI is a medical formula of weight divided by height. Bariatric surgery is typically recommended for patients with a BMI of 35 or above with an obesity-related complication such as hypertension or Type 2 diabetes or a BMI greater than 40 without any complications.
“Rather than looking at bariatric surgery as a weight-loss procedure, we need to change the narrative to describe what it really is – a preventive and therapeutic metabolic surgery. And we should discuss it with patients before chronic, potentially fatal metabolic conditions develop.”
New guidelines that were recently published by the major US and international bariatric surgery societies propose that patients should be considered for bariatric surgery at lower BMI such as greater than 30 with an obesity-related complication or greater than 35 without a complication.
Some groups are considered to have obesity at a lower BMI as they are at risk for obesity-related complications at lower body weights. For example, in patients of South Asian ethnicity,
A BMI over 25 kg/m2 suggests clinical obesity, and individuals with a BMI over 27.5 kg/m2 can be offered bariatric surgery.
Assigning a specific weight loss goal as a number of pounds is too broad and not individualized to the patient or the health conditions we may be trying to prevent or treat.
Research shows that a weight loss of 10% of body weight significantly reduces the risk of major cardiovascular events and can alleviate comorbidities such as Type 2 diabetes, high blood pressure, and fatty liver disease. Studies show that greater magnitudes of weight loss can lead to remission in conditions like Type 2 diabetes and may prevent certain cancers.
Many of our patients who complete bariatric surgery achieve weight loss, ranging from 15% to 40%. This degree of weight loss can positively impact four major areas of metabolic risk associated with obesity.
Reducing the Big 4 metabolic risks
Research shows that bariatric surgery can reduce cardiovascular events – including coronary artery disease events, stroke, heart failure, and atrial fibrillation – by 39%. Even in people with established heart disease, all-cause mortality declines.
Goal: Complete cardiometabolic bariatric surgery to decrease or resolve risk factors associated with cardiovascular disease and to decrease the long-term risk for cardiovascular disease or further events in those with established disease.
Type 2 diabetes
The more weight you lose with bariatric surgery, the better your chances of reversing Type 2 diabetes. And the sooner you receive the procedure, the better your outcomes.
The updated diabetes treatment guidelines from the American Association of Clinical Endocrinology suggest that offering people with Type 2 diabetes and obesity bariatric surgery sooner, rather than exhausting other weight loss options first, can almost double the chances of diabetes remission.
People with Type 2 diabetes and a BMI above 35 should be recommended for bariatric surgery because of the benefits on blood sugar control and decreasing diabetes complications. Patients with a BMI of 30-35 and inadequately controlled diabetes can also be considered for bariatric surgery.
In patients who had surgery after having Type 2 diabetes for less than one year, more than 90% experienced remission of their diabetes at two years after surgery. For those who underwent surgery after having Type 2 diabetes for four years or more, about 40% achieved remission at two years.
You can almost double your chance of Type 2 diabetes remission if you have bariatric surgery sooner. But this is the exact opposite of what we currently do in the U.S.; many providers and patients believe people can overcome obesity and Type 2 diabetes by drinking more water, exercising more, and dieting. While that may be true for some, taking this approach may not set people up for success, especially for those with multiple obesity-related complications.
Goal: Aim for at least a 20% weight reduction with bariatric surgery to maximize the chances of Type 2 diabetes remission and fewer diabetes complications. This is part of our recommendations in UTSW’s Weight Wellness Program.
Fatty liver disease
About 25% of the U.S. population – more than 83 million people – have nonalcoholic fatty liver disease, including half of people with Type 2 diabetes. Interestingly, people with Type 2 diabetes and fatty liver who undergo bariatric surgery are more likely to get rid of their diabetes than people without fatty liver.
Fatty liver disease is due to excess fat accumulation in the liver caused by a combination of genetic and lifestyle factors. When fat is stored in and around organs like the liver, it is called ectopic fat. Researchers have found that ectopic fat causes insulin resistance and weight loss rids the body of excess fat and decreases insulin resistance, which improves the chances of diabetes remission.
More than 90% of people who achieve greater than 10% weight loss will achieve remission from liver inflammation (steatohepatitis) caused by fatty liver disease. A recent study showed that people with fatty liver inflammation who completed bariatric surgery had an 88% reduction in the risk of adverse liver outcomes such as cirrhosis, liver cancer, need for liver transplant, or death related to liver disease.
Goal: Aim for more than 10% weight loss and consider bariatric surgery.
Related reading: Obesity amplifies genetic risk of nonalcoholic fatty liver disease
Having excess body fat can increase inflammation, which can contribute to insulin resistance, thereby leading to increased growth factors. When a patient also has Type 2 diabetes, they face double the cancer risk.
In the Swedish Obesity Study, patients with Type 2 diabetes who completed bariatric surgery had approximately 50% fewer cases of cancer 30 years later compared with those who did not have surgery.
Research has shown that greater weight loss after bariatric surgery was associated with greater reductions in cancer risk – and not just for those cancers that are identified as obesity-related. Some of the cancer types that were reduced include:
- Colon and rectum
Recent research highlights the benefits that bariatric surgery can have beyond weight loss and improvements in traditional obesity-related complications such as hypertension and Type 2 diabetes. It also highlights the importance of optimizing weight loss after surgery and helping patients to maintain a healthier weight long-term.
Maintaining a healthy weight is an effective cancer prevention tool and keeping the weight off is equally important. We work closely with specialists in UTSW’s Breast Cancer team, which often refers patients to us to achieve a healthier weight after breast cancer.
Goal: Consider bariatric surgery in those with obesity who may be at greater risk for cancer.
Bariatric surgery is metabolic surgery
Patients who have bariatric surgery get much more from it than just weight loss. By treating obesity, we have a chance to reduce their risk of preventable, chronic diseases such as diabetes, as well as to treat obesity-related complications if they have already developed. New bariatric surgery guidelines that now recommend surgery at lower body weights will allow people to treat obesity more effectively and prevent complications.
We must stop thinking of bariatric surgery as solely a weight loss treatment. Instead, we should think of it as a procedure that can prevent, eliminate, or significantly reduce complications of obesity that include Type 2 diabetes, fatty liver, cardiovascular disease, and some cancers.
To schedule a bariatric surgery consultation, call 214-645-8300 or request an appointment online
Meet Dr. Almandoz
Jaime Almandoz, M.D., an endocrinologist and Director of UT Southwestern's Weight Wellness Program, is passionate about helping people overcome the chronic and complex condition of obesity. His research and clinical expertise have made Dr. Almandoz a national recognized leader in the field of obesity medicine.