Metabolic Surgery Provides Effective Treatment for Obesity by Restructuring Digestive System and Regulating Gastric Hormone Secretion

Dr. TONG King Hung, Daniel

Honorary Consultant in General Surgery

Specialist in General Surgery

Most obese patients also have diabetes, i.e. diabesity, and they used to be blamed for their own condition due to some personal flaws: how could someone become obese except for lack of discipline? Couldn’t they cut down on their weight by just eating less and exercise more?

Thanks to the latest advances in medicine, we are beginning to understand obesity for what it is: an error of metabolism in the body.  

Weight Reduction Needs More than Determination

As a hunger hormone, ghrelin acts on the brain to promote appetite. Ghrelin secretion increases as obese patients experience metabolic imbalance, making them unable to control their eating. Due to inadequate production of insulin or insulin resistance, obese patients also often suffer from diabetes as their blood glucose levels increase.  Conventional treatment focuses on putting the condition under control with medication and lifestyle modification when it is still mild, with insulin injection as the last resort. Complications often appear after one or two decades of diabetes.

Mere persistence in dieting and exercise cannot achieve long-term weight loss. According to a published long-term follow-up study, obese patients could achieve no effective weight loss with whatever methods if their BMI was above a certain point, including dieting and exercise under professional guidance and supervision, Real, sustained weight loss was noted in only about 5% of participants in the study.

Due to problems with hormone secretion, some patients fail in weight reduction or achieve only short-lived results. As wrong signals are sent to the brain and therefore disrupt metabolism, it results in unwarranted weight gain or limited weight loss in obese patients despite all efforts. To treat metabolic syndrome caused by hormone disruption, metabolic surgery (also named bariatric surgery) is performed by specialists in general surgery with a view to restructuring the digestive system and regulating hormone secretion. More effective than lifestyle modifications and medications, it can help maintain an ideal weight, resolve or delay complications, even provide a cure for diabetes. 

Restructuring the Intestines and Regulating Hormone Secretion with Metabolic Surgery 

There are over 20 types of metabolic surgery. Locally, around 300 metabolic surgeries are performed each year. Unlike placement of intragastric balloons (which induces satiety mechanically in patients to achieve weight reduction), metabolic surgery involves the restructuring of the digestive system through sleeve gastrectomy or the less common laparoscopic Roux-en-Y gastric bypass based on individual condition.       

Sleeve gastrectomy can achieve weight reduction by reducing the stomach size. A large portion of stomach is removed to create a sleeve-shaped, much smaller version, thereby shortening the digestion period. With the hunger hormone-producing fundus also removed during surgery, patients are less likely to feel hungry and have a lower appetite after sleeve gastrectomy. It also results in early entry of food into the intestines. With the ensuing secretion of two hormones by the distal intestinal wall, namely glucagon-like peptide 1 (“GLP-1”) and peptide YY (“PYY”), the pancreas is stimulated to release insulin, keeping the blood glucose levels effectively in check after eating. A safe, simple procedure with a low long-term complication rate, sleeve gastrectomy accounts for 80 to 90% of metabolic surgery. The quality of life is also satisfactory for most patients after surgery.  

By comparison, the two-step laparoscopic Roux-en-Y gastric bypass is more complex than sleeve gastrectomy. In laparoscopic Roux-en-Y gastric bypass, the stomach is first divided with the proximal stomach being turned into a small stomach pouch of 150ml to limit food intake. It is followed by the rerouting of duodenum and proximal jejunum to decrease nutrient absorption, as the proximal small intestine is connected to the newly created stomach pouch. After surgery, the food can quickly pass through the stomach pouch and directly reach the distal small intestine. Laparoscopic Roux-en-Y gastric bypass is more effective then sleeve gastrectomy in treating type-2 diabetes. It can improve blood glucose levels by lowering appetite and decreasing the production of an appetite-stimulating hormone called incretin. But the downsides include longer operating time and higher surgical risk. Also it adds to difficulties in examining the distal stomach by gastroscopy, and is therefore not desirable for Asians, given their higher incidence of stomach cancer.  

While long-term use of supplements or stomach medicine is not required after sleeve gastrectomy, patients are required to take supplements for life after laparoscopic Roux-en-Y gastric bypass. In general, the risk of metabolic surgery is extremely low, i.e. anastomotic leakage (<5%), bleeding (<5%) or death (<0.1%), and the outcome is satisfactory in over 80 to 90% of patients. However, the fact that metabolic surgery can reduce food intake substantially doesn’t mean that you are now free to eat as much as you want, as obesity may return with a vengeance once you fall back on your old eating habits. You still need to adopt and adapt to a new eating habit after surgery, such as a low-fat, low sugar diet under dietitian guidance, as well as exercise regularly to maintain the outcome.  

Metabolic surgery is not recommended if patients fail to control their appetite due to the following conditions or remain unstable after certain procedures:

1. Mental disorders, e.g. schizophrenia

2. Congenital genetic problems

3. After heart valve surgery or heart transplantation and still in unstable condition

Case Studies：

1. A man of 50 had poor renal function and suffered from severe proteinuria. He was referred by his endocrinologist when medications failed, and in the absence of proper follow-up, might require renal dialysis, even renal transplantation after 5 years. With encouragement from his children, the patient agreed to undergo metabolic surgery, and was cured of proteinuria, diabetes and other related skin conditions. Instead of injections or renal transplantation, he now only needs low-dose diabetes medications.

2. A man in his late 20s was a heavy drinker with a BMI of 36. He also had severe diabetes, hypertension and fatty liver. Metabolic surgery was delayed when his aorta was found to be 3 times narrower than normal during pre-surgery examination. No metabolic surgery was carried out at last for unknown reasons. The patient was later diagnosed with renal cancer.

Effective in Preventing Complications with Inestimable Social Benefits

On overage, the lifespan of diabetes is 5 to 20 years shorter than normal people. Demonstrated by clinical data, metabolic surgery is proven to be effective in not only weight reduction but also producing significant benefits from the perspectives of personal health, medical insurance and society. While it takes time to achieve weight loss, thanks to the resulting changes in hormone mechanism, gastric probiotics and cholesterol circulation in the body, metabolic surgery can help return the blood glucose levels to normal within a short period of time and provide an effective cure for diabetes. It can also prevent or delay the onset of such complications as stroke, heart disease and renal failure in the long run without the need of dialysis for life or organ transplantation.

Consult your surgeon for details and receive proper treatment as advised before too late.