Bariatric Endocrinology: Obesity, Adiposity and Adiposopathy
October 2021
Volume 10, Issue 3

Chapter 3: Non-Invasive Procedures for Weight Loss

Radiology. 2019;291:792-800

Adipose tissue

The pharmacological treatment of overweight, obesity and adiposopathy is fraught with problems. Chief among them is the resistance of the medical community to prescribe them. For pharmacotherapy to be most successful, patients need to be educated on the concept of chronic disease management and the staged approach to its treatment. For most patients with chronic diseases, initial monotherapy will eventually need to transition to combination therapy. The current regulatory, financial, political and biased views on overweight and obesity, and ignorance about adiposopathy as a disease, continue to be major challenges in implementing effective medical treatment programs.

Bariatric surgery procedures are now firmly established as an additional treatment for overweight, obesity and adiposopathy. Outcomes data demonstrate that they improve survival and prevent the metabolic diseases associated with increasing fat mass. The American Society for Bariatric Surgery changed its name to the American Society for Metabolic and Bariatric Surgery (ASMBS) to reflect this knowledge.

Outcomes data allowed bariatric surgery to gain coverage from Medicare, which then opened the door for further coverage with third-party payers. Bariatric surgery is currently indicated for patients with overweight, obesity and adiposopathy who have significant burden from their disease. Patient selection is very important for successful outcomes with bariatric surgery. Every patient who undergoes bariatric surgery must understand that this is not a cure and that weight management needs to be for life. Every patient must also understand the long-term changes in physiology and metabolism that mandate ongoing, life-long, medical care. Re-intervention with pharmacotherapy to prevent weight regain after bariatric surgery is appropriate. Active surveillance for the development of nutrient deficiencies is necessary for all patients who undergo malabsorptive surgery.

There have been several studies that compared outcomes for glycemia, blood pressure and lipids between “intensive medical management” and bariatric surgery.  Every study documented that bariatric surgery was more effective in controlling all three areas of metabolic risk than medical management. The significant drawback of these studies is that formal treatment for obesity with currently available treatments was not implemented. There was failure of progression from monotherapy to combination therapy, and many patients in the trials did not receive any approved medications for weight loss. Treatments for glycemia, dyslipidemia and high blood pressure were put in place, but treatments for weight loss were not.

The decision to refer a patient to bariatric surgery is not trivial. Even in the age of laparoscopic procedures, there are significant short- and long-term risks for each of the bariatric procedures. The gap in weight loss between pharmacologic monotherapy and bariatric surgery has been an impetus for the development of bariatric surgery programs. This same gap is covered with progression of pharmacologic monotherapy to combination therapy. The gap is also the focus of “middle ground” procedures that do not involve entering the abdominal cavity. This chapter, and the next one, will review FDA-approved treatments currently in the US market, and briefly touch upon other treatments that are under development.

New devices in medical practice require FDA approval. Procedures, on the other hand, do not. The same procedure may be done differently by different surgeons, and therefore there may be variable success and complication rates for each bariatric procedure. To address this issue, a world concensus meeting was held in Deli, India, for standardization of bariatric metabolic procedures. The recommendations were published in July 2019. 

With devices, there is uniformity in use, which the regulatory process ensures. Of note, results are sometimes reported as absolute mass lost (i.e., pounds) from baseline. But many papers report percent of total entry weight loss, or percent of excess body weight loss. In assessing efficacy, it is important to distinguish the manner in which data is reported.

As of June 2021, there are four types of FDA-regulated devices intended for weight loss:

  • Gastric band
    • Adjustable gastric banding system (requires entering the abdominal cavity for placement)
  • Electrical stimulation systems
    • Rechargeable system (requires entering the abdominal cavity for placement)
  • Gastric balloon systems (requires endoscopy for placement, retrieval or both)
    • Intragastric balloon system
    • Balloon system
    • TransPyloric Shuttle/TransPyloric Shuttle delivery device
  • Gastric emptying systems
    • Percutaneous gastrostomy

As of June 2021, there are two types of FDA-regulated devices to aid with weight management; both of which do not require any invasive procedures:

  • Oral removable palatal space-occupying device
  • Ingested transient space-occupying device

This section will discuss the non-invasive devices for weight loss, as well as non-endoscopic procedures and devices.

Oral removable palatal space-occupying device

Devices and procedures for weight loss work by causing malabsorption of nutrients, altering afferent or efferent signals from the gut to the brain or restricting the volume of meals by decreasing capacity for food intake. The oral cavity is the first place where restriction of food boluses may take place.

The observation that a person with a sizable torus palatinus took longer than others to eat a meal, and that this person kept at a lean weight due to decreased caloric intake, led to the development of the oral removable palatal space-occupying device. It is a removable palatal retainer that is individually manufactured to fit the patient’s palatal and dental anatomy. Molds are made in the office and shipped to the manufacturer. Within the body of the retainer is a temperature sensor and a chip that stores this information. The temperature data translates into time used and adherence data for the individual. The chip data is transferred through a wireless mechanism to a reader. The reader data is then uploaded to the company’s database, which trends usage data. Weight data is also recorded, and company staff offer coaching to encourage mindful eating.

Ingested transient space-occupying device

The ingested transient space-occupying device is a superabsorbent hydrogel made of modified cellulose cross-linked with citric acid. It is ingested in three capsules with 500 mL of water 30 minutes prior to lunch and dinner (6 capsules total daily dose). Expansion comes about from rapid absorption of water by the particles. This causes a three-dimensional matrix of expanded particles to form. The particle expansion is designed to mimic the three dimensional structure of naturally occurring dietary fibers in vegetables. The hydrogel can uptake fluids to be up to 100 times its original weight fully hydrated. The particles do not aggregate, but do form a matrix that resembles ingested fiber.

These particles occupy volume in the lumen of the stomach, achieving the elasticity of solid ingested foods and leading to fullness with less ingested meal volume. Compared to other fibers, the superabsorbent hydrogel has the capacity for occupying more volume longer in the lumen of the stomach. The particles remain hydrated in their passage through the small intestine, but the three-dimensional structure is lost due to the effects of digesting enzymes. The particles release their water content in the colon and then pass with the stool. There is no absorption of the hydrogel into the circulation, so there is no pharmacological effect.

The superabsorbent hydrogel is the easiest device to put into use.  There are no procedures required for the patient to start. In clinical trials there was no significant difference in side effects compared to placebo. As a very safe intervention, it stands to add to the pharmacotherapy interventions for weight management.

Investigational

Fecal transplantation (fecal microbiota transplantation) is under investigation for treatment of overweight, obesity and adiposopathy in humans. In germ-free mice the transfer of fecal microbiota from human donors determines phenotype. Mice receiving microbiota from people with obesity accrue excess fat mass. Mice receiving microbiota from people who are lean do not accrue excess fat mass. Preliminary results from studies in humans are encouraging that this may soon become an effective treatment.

Bariatric embolization, in the realm of interventional radiology, has been shown to be a safe and effective treatment for excess weight. By embolizing the left gastric artery, which supplies the gastric fundus, there is a marked reduction in the production of ghrelin.  Ghrelin, produced by the stomach, is the only known hormone to produce hunger. Suppressing ghrelin suppresses hunger. The Gastric Artery Embolization Trial for Lessening of Appetite Non-surgically (GET LEAN) showed that this approach is feasible. The Bariatric Embolization of Arteries for the Treatment of Obesity (BEAT Obesity) trial is ongoing. Up to date the magnitude of weight loss is on the par with endoscopic procedures or combination pharmacotherapy.

Commentary

Next Article:
Chapter 4: Endoscopic Procedures for Weight Loss
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