Weight-loss surgeries are procedures that can be used to cause significant weight loss if you are very obese.

Weight-loss surgeries lower the body's intake of calories, which help you lose weight. Calorie reduction occurs in two ways:

• After the surgery, your stomach is smaller. You feel full or satisfied faster and learn to reduce the amount that you eat at any given time. (This is called a restrictive procedure)
• When you eat, the food skips over part of your stomach and small intestines so that they absorb fewer calories. Unfortunately, sometimes nutrients are lost as well. (This is called a bypass or malabsorptive procedure.)

Some surgeries use both of these techniques.

Before any weight-loss operation, your doctor will give you a complete medical examination and evaluate your overall health.

You also will have a psychological evaluation. This will determine whether you are ready to stick to a healthier lifestyle. If you are not ready to make lifestyle changes (and have not tried hard to do so already), you will not be considered eligible for the procedure. Without changing your lifestyle, the surgery will not be a success.

You will also receive nutritional counseling before and after your surgery.

GASTRIC BYPASS

Roux-en-Y gastric bypass is the most common surgery of this type.

The surgery is performed under pain-killing medicine (anesthesia). There are two basic steps:

• STEP 1 -- The first step in the surgical procedure makes your stomach smaller. The surgeon divides the stomach into a small upper section and a larger bottom section using staples that are similar to stitches. The top section of the stomach (called the pouch) will hold your food.
• STEP 2 -- After the stomach has been divided, the surgeon connects a section of the small intestine to the pouch. When you eat, the food will now travel from the pouch through this new connection ("Roux limb"), bypassing the lower part of the stomach. The surgeon will then reconnect the base of the Roux limb with the rest of the small intestines from the bottom of the stomach, forming a y-shape.

This "y-connection" allows food to mix with pancreatic fluid and bile, helping to absorb important vitamins and minerals. You still may have poor absorption of certain nutrients.

The risk of poor absorption is of greater concern in gastric surgeries that skip over a larger portion of the small intestines. These are performed much less often than the Roux-en-Y gastric bypass described here.

Gastric bypass can be performed as open surgery with a larger surgical cut in the abdomen.

It may also be done using a camera placed in the abdomen (laparoscopy). This less-invasive technique allows the surgeon to make smaller surgical cuts, which lowers the risk of large scars and hernias after the procedure.

First, small surgical cuts are made in your abdomen. The surgeon passes thin surgical instruments through these narrow openings. The surgeon also passes a camera (laparoscope) through one of these small openings and watches through a lens and video monitor to do the surgery.

Not everyone is a candidate for the laparoscopic approach. Your surgeon will determine the best and safest approach for you.

You may NOT be a good candidate for laparoscopy if you:

• Have had past abdominal surgery, due to scar tissue
• Have significant heart and lung disease
• Weigh more than 350 pounds

Gastric bypass tends to work better for weight loss than purely restrictive surgeries. However, your body may not absorb vitamins and minerals properly.

LAPAROSCOPIC ADJUSTABLE GASTRIC BANDING (Lap-Band, LAGB)

A newer procedure, called the Lap-Band, places a band around the upper part of the stomach, creating a small pouch to hold food. The band limits the amount of food you can eat, and increases the time it takes the intestines to digest the food.

Your doctor can later adjust the band to allow food to pass more slowly or quickly through your digestive system. Possible complications include nausea, vomiting, and gastroesophageal reflux.

Final weight loss with gastric banding is not as much as with gastric bypass. However, it may be enough for many patients. You should talk to your physician about which procedure is best for you.

Weight-loss surgery may be an option if you are very obese and have tried unsuccessfully to lose weight on diet and exercise programs and are unlikely to lose weight successfully with nonsurgical methods.

Gastric bypass surgery is not a "quick fix" for obesity. The surgery can take several hours and has risks and possible complications. For example, people can vomit after the surgery if they eat more than the new, small stomach can hold.

Your commitment to diet and exercise must be very strong because even after the surgery, you must stick to these lifestyle changes. Otherwise, you are likely to have complications from the surgery.

The procedure may be considered for obese individuals who have:

• A Body Mass Index (BMI) of 40 or more. BMI is a calculation based on height and weight that is used to determine whether you are of normal weight or are overweight. Someone with a BMI of 40 or more is at least 100 pounds over their recommended weight. A normal BMI is between 18.5 and 25.
• A BMI of 35 or more along with a life-threatening illness that can be made better with weight loss, such as sleep apnea, type 2 diabetes, and heart disease.

The risks of weight-loss surgery include:

• Anemia from iron or vitamin B12 deficiencies
• Bleeding
• Breakdown of the pouch needing repair
• Calcium deficiency, which can contribute to the development of early osteoporosis or other bone disorders
• Death from breathing (respiratory) failure, blood clots to the lungs, or problems with the bypass procedure
• Follow-up surgeries to correct complications, or to remove extra skin
• Gallstones and gallbladder attacks
• Gastritis and heartburn
• Infections
• Malnourishment
• Vomiting from eating more than the stomach pouch can hold

Follow-up surgeries may be less likely if gastric bypass is done with a laparoscope.

Another common complication from weight-loss surgery is "dumping syndrome." The symptoms often include:

• Bloated feeling
• Diarrhea
• Dizziness
• Nausea and vomiting
• Sweating

The weight loss results of gastric bypass surgery are generally good. Most patients lose an average of 10 pounds per month and reach a stable weight 18 - 24 months after surgery. Often, the greatest rate of weight loss occurs in the very beginning (just after the surgery when you are still on a liquid diet).

Losing enough weight as a result of surgery can improve or even relieve many medical problems, such as:

• Asthma
• High blood pressure (hypertension)
• Obstructive sleep apnea
• Stress incontinence

After the surgery, you will need to follow up with your doctor fairly often during the first year. During those visits, your physician will be checking your physical and mental health, including any change in weight and your nutritional needs. You will likely see a dietitian during those visits as well.

The surgery is not a solution by itself. Although it can train you to eat smaller amounts of food and feel full more quickly, you still have to do much of the work. To lose weight and avoid complications from the procedure, you must exercise and eat properly -- according to important, healthy guidelines that your doctor and nutritionist will teach you.

Most people stay in the hospital for a few days or less after gastric bypass surgery. Some may need to stay 4 - 5 days. Your doctor will approve your discharge home once you can do the following:

• Eat liquid and/or pureed food without vomiting
• Move without too much discomfort
• No longer require pain medication given by injection

You will remain on liquid or pureed food for several weeks after the surgery. Even after that time, you will feel full very quickly, sometimes only being able to take a few bites of solid food. This is because the new stomach pouch at first only holds a tablespoonful of food.

The pouch eventually expands. However, it will hold no more than about one cup of chewed food (a normal stomach can hold up to one quart).

Upon follow-up, your doctor will determine if you need replacement of iron, calcium, vitamin B12, or other nutrients. Supplements, such as a multivitamin with minerals, can provide any nutrients that you may not be getting from your diet. This lack of nutrients can occur because you are eating less and because the food moves through your digestive system more quickly.

Once your diet begins to consist of more solid food, remember to chew each bite very slowly and thoroughly.

You will be instructed to eat small meals (usually six meals) often throughout the day, rather than large meals that your stomach cannot handle.

Your new stomach probably won’t be able to handle both solid food and fluids at the same time. You should separate fluid and food intake by at least 30 minutes and only sip what you are drinking.

You won’t be able to tolerate large amounts of fat, alcohol, or sugar. You should reduce your fat intake, especially:

• Deep-fried foods
• Fast-food meals
• High-fat foods
• High-sugar foods such as cakes, cookies, and candy

Exercise and the support of others (for example, joining a support group with people who have undergone weight-loss surgery) are extremely important to help you lose weight and maintain that weight loss after gastric bypass.

You can usually start exercising again 6 weeks after the operation. Even sooner than that, you will be able to take short walks at a comfortable pace, with the approval and guidance of your doctor. Exercise improves your metabolism, and both exercise and attending a support group can boost your self-esteem and help you stay motivated.

Frank A. Bariatric surgery: too many unanswered questions. Am Fam Physician. 2006;73:1403-1408.

Virji A, Murr MM. Caring for patients after bariatric surgery. Am Fam Physician. 2006;73:1403-1408.

Allen JW. Laparoscopic gastric band complications. Med Clin North Am. 2007;91:485-497.

Leslie D, Kellogg TA, Ikramuddin S. Bariatric surgery primer for the internist: keys to the surgical consultation. Med Clin North Am. 2007;91:353-381.

Townsend Jr. CM, Beauchamp RD, Evers BM, Mattox KL. Townsend: Sabiston Textbook of Surgery. 18th ed. Philadelphia, Pa: Saunders; 2008.

Buchwald H, Estok R, Fahrbach K, Banel D, Sledge I. Trends in mortality in bariatric surgery: a systematic review and meta-analysis. Surgery, 2007;142:621-632.