Not all surgical weight-loss procedures work the same way. There are those that shrink the size of your stomach, those that limit how much food your body absorbs, and those that do both.

There are many things to consider when choosing the procedure that is right for you. An important consideration is long-term results: What is the best way to lose the most weight safely and keep it off?

To answer this question, researchers reviewed the findings of 29 studies on gastric bypass and gastric banding weight-loss procedures, looking at how much weight people lost on average with each procedure and what the risk of medical complications for each surgery tended to be.

It's more important to look at the long-term effects of treatments like surgery rather than their short-term benefits, since obesity, type 2 diabetes, hypertension, and elevated cholesterol are chronic, long-term illnesses.

Approximately 120,000 weight-loss surgeries are performed each year in the US, and gastric bypass is the most common. The procedure, known as Roux-en-Y, is the gold standard for bariatric surgery. The technique bypasses a portion of the stomach and small intestine, creates a small stomach pouch, which restricts food intake, and then with a shorter intestine you absorb fewer calories.

Gastric banding uses an adjustable band to create a small pouch at the top of the stomach which limits the amount of food that can be consumed and slows down the release of food into the intestine.

Gastric bypass surgery outperformed gastric banding for weight loss. People who had gastric bypass lost an average of 66 percent of their excess weight compared to 45 percent for those who had gastric banding performed.

“We know gastric bypass brings more weight loss success and relief of commonly-associated illness versus gastric band at one year after surgery…We also know these procedures maintain their safety profile long-term,” researcher Nancy Puzziferri, part of the bariatric surgery team at UT Southwestern said in a statement.

More people with type 2 diabetes, hypertension, and hyperlipidemia experienced remission of these diseases after gastric bypass when compared to gastric banding.

It's more important to look at the long-term effects of treatments like surgery rather than their short-term benefits, since obesity, type 2 diabetes, hypertension, and elevated cholesterol are chronic, long-term illnesses, according to Dr. Puzziferri.

The risk for long-term complications for both procedures was low, but gastric bypass had a slight advantage over gastric banding.

Gastric sleeve procedures were not part of the review because too few studies have been done on them. They appear to have the same advantages of gastric bypass surgery for weight loss, but more evidence is needed before they can be fully evaluated.

Both procedures make patients feel full more quickly so they eat less and lose weight. Even after surgery, however, people must make lifestyle changes and pursue healthy eating habits and physical activity to achieve long-term successful results.

The review was published in JAMA, the Journal of the American Medical Association.