TUESDAY, September 16, (News Locale) - Morbidly obese patients are advised gastric bypass surgery as a last resort to lose unwanted weight. However if these individuals have diabetes, the surgery may not help much, according to a new study.

Researchers at the University of California, San Francisco analyzed data from 310 patients who had undergone gastric bypass surgery. Among them 114 patients had diabetes at the outset. Ideal weight loss after surgery was defined as losing more than 40 percent of the pre-surgery body weight.

Overall the participants had an average body mass index (BMI) of 52 prior to undergoing gastric bypass surgery. Some 12 months after the surgery the average BMI was 34 in a majority of the participants who had lost at least 60 percent of excess weight.

However 38 patients did not have the desired weight loss and in fact lost less than 40 percent of excess body weight even after the surgery.

The researchers took into consideration various confounding factors before concluding diabetes and excessive stomach size were linked to poor weight loss following gastric bypass surgery.

"When performed in high-volume centers and with a low rate of complications, gastric bypass provides sustained and meaningful weight loss, significant improvements in quality of life, improvement or resolution of obesity-associated co-morbidities, and extended life span," the researchers, led by Dr. Guilherme Campos, director of the Bariatric Surgery Program at University of California, San Francisco, write in the September issue of the journal Archives of Surgery.

The theory is insulin and other drugs taken to control blood sugar in diabetic individuals stimulate the production of body fat and excess cholesterol. Hence diabetic patients gain weight even after remedial surgery.

According to the National Institute of Diabetes and Digestive and Kidney Diseases, bariatric surgery produces weight loss by restricting food intake and, in some cases, interfering with nutrition through malabsorption. There are four types of gastric surgery for severe obesity; adjustable gastric band (AGB), Roux-en-Y gastric bypass (RYGB), gastric sleeve (GS), and biliopancreatic bypass with a duodenal switch (BPD).

In the present study Roux-en-Y Gastric Bypass, which works by restricting food intake and by decreasing the absorption of food.

Commitment to weight loss is often a pre-requisite in these types of surgeries. However the presence of diabetes complicates matters and requires strict dietary regime to control weight even after surgery.