This is the most common of the gastric bypass procedures, allowing small amounts of food to be tolerated and some calories to be absorbed.

The RGB operation staples and divides the upper stomach horizontally, leaving a small pouch with approximately a one-ounce capacity. Three types of RGB operations are available:

Proximal: This is the most common surgical weight loss procedure and the least aggressive gastric bypass. It reduces absorptive capacity of the small intestine by 20%. Five-year weight loss averages 50%-75%.

Medial: This moderately aggressive gastric bypass reduces the absorptive capacity of the small intestine by 50%. Five-year weight loss averages 70%-80%.

Distal: The most aggressive gastric bypass, it reduces the absorptive capacity of the small intestine by 70%-80%. More than half the calories ingested are not absorbed and the distal patient must take more vitamin, mineral and protein supplements than other bypass patients. The five year weight loss averages 75%-85%.

Gastric bypass is one of the most time-tested procedures for long-term weight loss. In most cases it can now be performed laparoscopically—as a minimally invasive surgery that results in fewer complications and less pain during recovery.