What is the "Goldilocks" length in Bariatric Surgery?

In a SADI-S surgery, a loop of small intestine is brought up and connected to the end of the sleeve stomach.  This loop of small intestine is typically 300 cm from the end of the small intestine.  In this configuration, approximately 50-60% of the small intestine is bypassed, leaving 300 cm available to absorb calories. 

Why is it 300 cm?  Studies have shown that this the “Goldilocks” length of small intestine.  If we make this loop of small intestine too short, for example only 100 cm, there may be slightly more weight loss, but there will not be enough small intestinal length available to absorb necessary vitamins, resulting in higher chances of malnutrition.  In contrast, if we make this loop too long, for example 600 cm, there will be too much small intestine available to absorb calories, and therefore, there will not be enough weight loss.  

Studies have shown that 300 cm seems to be the right amount of small bowel length.  300 cm is enough small intestine to absorb vitamins and therefore, rates of malnutrition or chronic diarrhea are low.  300 cm is also short enough that there is excellent weight loss after surgery, with average excess weight loss between 70-90%.  The SADI-S therefore offers more average weight loss than the sleeve or gastric bypass.  The SADI-S is an excellent primary / initial bariatric surgery and is also a great option for revisional surgery after a sleeve gastrectomy.