Last week’s FBR blog examines the growing rates of obesity in pet cats and dogs, as well as interventions reached through animal research that could help curb the epidemic. This post is devoted to the myths surrounding bariatric weight-loss surgery in human patients, and the studies with animals that have led to new medical knowledge on the subject.  

Yet again, polls have shown the three most popular goals to which people have committed themselves in the new year remain, in this order: exercise more, lose weight, and eat more healthfully.

As millions of Americans have learned, lifestyle changes are difficult to adopt, and perhaps even harder to maintain. US News reports approximately 80 percent of people will fail to keep their resolutions by the second week of February.

For many people, healthy changes to diet and exercise simply aren’t enough.  Their weight is an acute health issue that requires medical intervention in addition to supplemental lifestyle adjustments. And today, there are more options than ever to help them get healthier.

In these cases, for patients who are morbidly obese (more than 100 pounds overweight), with a body mass index (BMI) greater than or equal to 40—far above the 19-25 range that’s generally considered healthy—physicians may recommend bariatric surgery. There are several different types of bariatric procedures, but they all reduce the size of the patient’s stomach, leading to weight loss: In what is called a sleeve gastrectomy, 85 percent of the organ is surgically removed—laparoscopically, through small incisions with the aid of a camera—and the shape of the stomach thereafter resembles a tube, or a sleeve. A gastric bypass, by contrast, is performed by dividing the stomach into an upper pouch and a much larger, lower “remnant” pouch, causing a reduction in the functional size of the stomach.

Each available surgery was made possible by animal research, primarily involving rodents. Together, they represent a milestone in the fight against obesity. These treatment options are especially welcome considering the number of obese adults has increased, now exceeding 35 percent in five states (LA, AK, AL, MS, and WV). And the number of Americans living with diabetes or prediabetes also rose to more than 100 million in 2017.

Patients who undergo bariatric surgery must still adopt healthy diet and exercise habits, as they must work to maintain long-term weight control. They also face possible risks associated with the procedure, ranging from blood clots and gastro-intestinal leakage to hernias and gallstones. But in research labs and clinics, scientists and physicians have witnessed the tremendous success of these procedures in helping patients successfully lose weight. The New York Times quoted a clinical epidemiologist who concluded from her experience with significantly overweight patients, and from her analysis of studies on weight-loss surgery, that it “is probably the most effective intervention we have in healthcare.”

People who undergo weight-loss surgery report lasting benefits to their health and well-being. The results of studies that tracked patients for five to 25 years post-op show they are likelier to have longer lives, and most will maintain their weight loss in the long-term. This research contradicts some popular misconceptions, especially among people outside the scientific and medical establishment—many of whom believe, incorrectly, that patients who undergo gastric bypass or gastric sleeve generally regain the weight.

Adding to the results of clinical studies with human patients is the new knowledge gained from animal research, which helps to explain more comprehensively the mechanisms by which bariatric surgery leads to weight loss. These studies have helped scientists and clinicians better understand why such procedures are safe, and why they have lasting results.

In gastric bypass, weight loss is caused partially—though, as researchers learned through studies with rodents, not entirely—by a mechanistic process. Since the patient’s stomach has been cordoned off into two portions, weight loss occurs because the patient’s body absorbs fewer calories, and less food can be consumed with the newer, smaller stomach.

Researchers have also learned in recent animal studies that other factors play a significant role in weight loss after surgery. Among them, changes in blood circulation and brain signaling, which have been linked to reduced food consumption.

More compellingly, researchers and clinicians have learned in studies with rodents precisely how and why weight-loss surgery leads to rapid improvements in diabetic conditions, cardiovascular health, and metabolism function. In one study, stool from human patients was collected after their surgeries and implanted into mice. As a result, the bacterial composition of the rodents’ guts was changed in such a way that harmful fat deposits were reduced. In this way, the researchers determined patients who undergo bariatric surgeries develop bacteria that stimulate metabolic function and weight loss/maintenance.

As animal research leads to more evidence of the safety and long-term effectiveness of bariatric surgery, it may become more common and more accessible. This is good news for many in the scientific and medical communities who generally consider these procedures underutilized tools that could be better harnessed to treat morbidly obese patients.

As obesity rates continue climbing among people and pets, animal research will facilitate new and more effective treatment options—as well as new knowledge about the complex and interrelated topics of diet, exercise, weight maintenance, and surgical intervention.

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