Roux-en-Y Gastric Bypass (RYGB) is a surgical procedure for weight-loss in morbid obesity patients. It is one of the most common types of bariatric surgery in the United States. Approximately 47% of obese patients undergoing surgery using the RYGB technique.

Roux-en-Y Gastric Bypass Weight-Loss: Mechanisms, Advantages, and Disadvantages
Roux-en-Y Gastric Bypass
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But this procedure is thought to be associated with long-term disadvantages, such as vitamin and mineral deficiencies. This operation can be performed laparoscopically (small incisions to the abdomen) or robotically (computer-assisted surgery used to aid in surgical procedures).

Roux-en-Y Gastric Bypass Mechanisms

How does gastric bypass help lose weight? There are two weight loss mechanisms in Roux-en-Y Gastric Bypass (RYGB), namely gastric restriction and mild malabsorption. The operation is carried out by separating a little part of the stomach and then making a small bag (pouch) about 10-20 mL from the part of the stomach separated. This small pocket will later become a productive gastric.

a. Restriction: the upper portion of the stomach separated from the lower portion. The upper portion (or the "pouch") is then connected to a limb of the small intestine, called the "Rouxlimb." The new stomach pouch restricts the amount of food, making it feel full after eating only a small amount of food.

b. Mal-Absorbtion: Create a pouch; the digestive system rerouted to bypass the larger part of the stomach and part of the small intestine. The bypass is to absorb fewer calories and nutrients from the food you eat (mal-absorption). 

Advantages and Disadvantages

a. Advantages Roux-en-Y Gastric Bypass

The Roux-en-Y Gastric Bypass (RYGB) procedure was reported to increase the YY and glucagon-like peptide levels from 2 days after it was performed, causing a decrease in appetite. In contrast to other methods, decreased appetite after RYGB was reported to be persistent.

On average, patients who experience Roux-en-Y Gastric Bypass (RYGB) can lose up to 60% of their initial body weight. A study on veterans in the United States with ten years of follow-up concluded that the RYGB method could lose more weight than the Adjustable Gastric Banding (AGB) or Sleeve Gastrectomy (SG) method.

In obese patients with type 2 diabetes mellitus, RYGB can lose weight accompanied by a decrease in HbAIc and cardiovascular risk that lasted longer than an intensive weight loss program.

RYGB also provides a greater benefit in improving the patient's quality of life. A systematic review published in 2018 concluded similar results. This study says that RYGB is more effective than SG in losing weight and improving glycemic control and lipid profile in the short-to-medium term.

The RYGB method is also associated with decreased blood pressure and increased insulin sensitivity and secretion. RYGB has also been reported to affect the bone remodeling process through adipocyte proteins related to the bone remodeling cycle. 

In polycystic ovary syndrome, RYGB improves patient fertility, reduces the abnormal menstruation incidence, and overcomes hyperandrogenism.

b. Disadvantages of the Roux-en-Y Gastric Bypass 

This procedure is not reversible, more pain, and a bit longer because the digestive organs are rerouted. 
Regaining weight is the least expected of patients undergoing Roux-en-Y Gastric Bypass (RYGB). A cohort in 2015 involving 300 study subjects showed that all participants experienced weight regain with an average of 23.4% of the weight-loss. Excess weight gain occurs in 1 in 3 patients.

In addition to weight gain, RYGB is also associated with malabsorption and nutrient deficiency. This procedure reduces the gaster's ability to absorb nutrients and calories, so it makes nutrient deficiency. Nutrient deficiencies often reported after RYGB are deficiencies of vitamin B12, iron, calcium, and folic acid. This deficiency can later lead to pernicious anemia, iron deficiency anemia, and other diseases.

Nutrient deficiency occurs in nearly 90% of patients and persists even when given vitamin and mineral supplementation. A systematic review by Weng et al. reported an increase in ferritin deficiency from 7.9% postoperatively to 13.4% at 12 months of follow-up and 23% at 24 months of follow-up. Vitamin B12 deficiency also increased from 2.3% postoperatively to 6.5% at 12 months of follow-up. This study also showed an increased anemia incidence from 12.2% postoperatively to 20.9% at 12 months of follow-up, and 25.9% at 24 months of follow-up.

Roux-en-Y Gastric Bypass (RYGB) is a surgical procedure for weight loss in morbid obesity patients. This procedure is performed by separating a little part of the stomach and then making a small bag (pouch) about 10-20 mL from the part of the stomach separated.

RYGB can affect gastrointestinal hormones, thereby reducing appetite and accelerating satiety. RYGB is also associated with significant weight loss, improved glycemic control, and improved lipid profile. However, several studies have also shown that RYGB is associated with a high incidence of weight regain and can lead to vitamin and mineral deficiencies.