More than a third of Americans are obese, suggesting that diet and exercise alone aren't enough for millions of people trying to slim down.

But they're not exactly clamoring for medical treatments for their disease, leaving a large and relatively untapped market for a number of new approaches that are in the pipeline.

Weight loss surgery is highly effective, but less than 2% of people who are candidates for it take that step, according to one estimate. "Patients are very reluctant to undergo surgery," says Caroline Apovian, the director of the Nutrition and Weight Management Center at Boston Medical Center. "They just don't realize that their obesity is not under their control, that it's a disease."

In January, the FDA approved the MAESTRO System, a pacemaker-like device designed to control hunger and fullness by blocking the vagus nerve, which extends from your brain to your stomach. The system, called the VBLOC, is one of a few intriguing approaches that researchers are studying as potential obesity treatments. VBLOC doesn't alter the stomach or intestine like many of the weight loss surgeries.

The devices represent a field energized by recent FDA approvals of four new obesity drugs: Qsymia in 2012, Belviq in 2013, Contrave this past September, and Saxenda in late December.

Sales of those treatments haven't taken off, though, in part because some people might not like the side effects, and some of the drugs aren't covered by insurance.

The history of failed obesity medications seems to have dampened people's enthusiasm for taking pills to help control their weight, says Harold Bays, MD. He's the medical director and president of the Louisville Metabolic and Atherosclerosis Research Center. "The problem is almost all of them ended up having bad side effects," Bays says.

Still, researchers continue to look for safer drugs, as well as for devices that might be more attractive than surgery.

These are some of the potential new treatments:

The ReShape Duo, a double balloon that is filled with saline and placed in the stomach for 6 months, has been on the market in Europe since 2007. It's intended to help people feel full, and it's under FDA review.

In a 6-month clinical trial of the device in obese patients in the U.S., more people who received the Reshape Duo device lost weight than those treated with counseling alone. The results were presented last November at the annual meeting of the American Society for Metabolic and Bariatric Surgery.

Nearly all patients had nausea, vomiting, and abdominal discomfort in the first few days. The symptoms went away in about a week, says Jaime Ponce, MD, a weight loss surgeon who led the study.

Gelesis100 is a cross between a pill and a device. It's a capsule filled with tiny particles created with raw materials used in food products.

The particles soak up water and expand in the stomach. They also mix with digested food and slow its passage out of the stomach, the company says. In a 12-week study reported at a medical conference last June, people on Gelesis100 lost 6.1% of their weight, compared to a 4.1% loss in a group of people who received a fake treatment.

The Elipse balloon, another device, has been revised several times. The researchers' goal was to make a balloon that could be placed in the stomach and removed without endoscopy, a procedure which usually requires sedation and a specially trained doctor.

Their latest model is attached to a long, thin, flexible tube. You swallow the balloon, which is then filled with about 15 ounces of water. The tube is then pulled out.

In its first human test, the balloon remained full for 6 weeks in six of eight people, researchers reported at last year's metabolic and bariatric surgery society meeting. Then it emptied and passed out of the body. Although the participants weren't prescribed diet or exercise, they lost 5 pounds on average. The balloon's maker, Allurion Technologies, is now doing a clinical trial in Europe, where it hopes to launch Elipse by early 2016.

The Obalon balloon works a little differently to help you feel full. First, you swallow a capsule that contains one balloon. The capsule dissolves and releases the balloon, which your doctor inflates through a tube attached to the capsule. The doctor then removes the tube. The doctor can place up to 3 balloons during the 12-week treatment. Then they are removed. The device is approved in several countries in Europe and in Mexico. In January, the company announced it had raised money to begin clinical trials in the U.S. In small studies, patients loss an average of 50% of their excess weight and 8% of their body weight, according to data provided by the company.

EndoBarrier is a thin, flexible liner placed at the beginning of the intestine. It's left in place for a year before being removed. Because it blocks food from a portion of the intestinal wall, it's supposed to alter the release of hormones that play a role in digestion.

Although it's not available in the U.S., it is on the market in several other countries. It's intended to treat obese people with a body mass index (BMI) of 35 or more, or those with a BMI of 30 or more with type 2 diabetes or at least one other obesity-related condition.

In the U.S., EndoBarrier is being studied to treat type 2 diabetes in obese people, maker GI Dynamics said in a statement.

Beloranib "allows the patient to burn off stored fat without feeling hungry," says Thomas Hughes, PhD. He's the CEO of Zafgen, the Boston company that developed the drug. The first drug of its type, beloranib is given in twice weekly injections.

Weight loss drugs already on the market "do not address the underlying problem in obesity," which is the way obese people metabolize fat, Hughes says. Trials of beloranib have shown that patients convert less of the calories they're eating into stored fat, and it stimulates the burning of fat that's already stored, he says.

Zafgen is seeking approval for beloranib for three conditions: Prader-Willi syndrome, a genetic disorder that causes unstoppable hunger and profound obesity; "acquired Prader-Willi syndrome," which results from the treatment of benign tumors in the middle of the brain; and severe obesity complicated by type 2 diabetes.

Mirabegron, approved by the FDA in 2012 as Myrbetriq to treat overactive bladder, might also help people lose weight. It works by activating a protein on bladder cells, which also is found on fat cells.

A study funded by the National Institutes of Health tested whether mirabegron could activate brown fat, a type of body fat that creates heat by burning calories.

A single high dose raised the metabolic rate -- the amount of energy the body burns at rest -- in 12 thin young men by an average of 13%, researchers reported Jan. 6 in Cell Metabolism.

"We don't know yet what to expect on metabolism in non-lean people," says Aaron Cypess, MD, PhD, of the National Institute of Diabetes and Digestive and Kidney Diseases.

He is planning longer-term studies of mirabegron in more diverse groups, including women and obese people.

Slideshow: Obesity and Diabetes Around the World

Booming Without Borders

It’s a dangerous trend with no end in sight. Obesity and diabetes are on the rise around the globe. Take a look at the shocking data.

10 Countries Stand Out

Over a billion people across the globe weigh in as obese. Over a third of the U.S.’s population falls into that category, followed closely by New Zealand, Australia, the United Kingdom, Mexico, Canada, Chile, Czech Republic, Slovakia and Ireland. The big picture is clear: The world is getting heavier. Global figures for obesity have nearly tripled since 1975. Worldwide, 39% of adults are overweight or obese, and so are 18% of children.

Little Islands, Big Waistlines

The islands of the South Pacific are not just a tropical paradise. They are also some of the most common places for people to be obese or overweight; especially women. In Tonga, where about 107,000 people live, 70% of women are overweight or obese and almost 47% of the men. In  Cook Island, it's 66% of women and 57% of men. Researchers say obesity in these countries comes from eating imported foods and adopting Western habits.

Who Eats the Most Calories?

Surprise: It's not the U.S. The top countries in the world for average daily calories stack up like this:  

  1. Austria: 3,768
  2. Turkey: 3,706
  3. U.S.: 3,682
  4. Ireland: 3,600
  5. Italy: 3,579 

To put those numbers in context, women should eat about  1,600-2,400  and men about 2,000-3,000 calories, depending on your age and how active you are. 

Sit or Cycle?

While 86% of Americans sit in traffic, nearly half of the Chinese walk or cycle to and from work. The Dutch, the Danes and the French are also big fans of a car-free commute. Those countries all have obesity rates below 20%, compared with roughly 37% in the U.S. Between work, commutes, and leisure time, nearly half of adults around the world sit for at least 4 hours a day.

The Diabetes Explosion

Globally, about 422 million people have diabetes. That's 8.5% of the world's population. Nearly half of them don't know they have it. About 60% of all people with diabetes are Asian. Doctors think Asians get it younger and at lower weights than Westerners.

The Numbers Keep Rising

Another 210 million people worldwide are expected to get diabetes by 2035. That's 10% of the world's population. Experts say this trend will continue as people become more urban, less active, and eat more calories -- all of which will make obesity even more common than it is now.

No Longer Just for Adults

Type 2, in which the body doesn't make enough insulin or can't use it properly, used to be an adult problem. Now it's showing up in kids and teens, too. Recently, there has been an almost 5% increase in the number of youths that are newly diagnosed each year with type 2 diabetes. Now, type 2 accounts for 90-95% of all cases diagnosed. In some parts of the world, more kids have type 2 than type 1, which usually shows up in childhood. Researchers say this is because obesity is on the rise in children, and kids are less and less active.

The Rest is History

While diabetes is breaking records worldwide, it's been around for a long time. The ancient Egyptians described diabetes 3,000 years ago. A papyrus dated around 1550 B.C. notes remedies “to eliminate urine which is too plentiful,” a common sign of high blood sugars. Today, about 16.7% of all Egyptians have diabetes. 

Reviewed by Melinda Ratini, DO, MS on November 10, 2017

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© 2015 WebMD, LLC. All rights reserved.

Slideshow: Can't Wait for the Future? Try These Weight Loss Tips Now

It’s OK to Lose Weight Fast

You’ve heard the mantra -- to keep weight off you need to lose slowly. Not so. Researchers tracked people for a year who dropped pounds slowly vs. those who took them off quickly. They found no difference in who kept the weight off and who didn’t. In fact, they say, some obese people just lose weight fast and no one knows why. Slowing it down could derail any chance of success.

Losing a Little Can Help

Here’s a weight loss hack that will get you to your goal and boost your health. Focus on losing 10 pounds -- or whatever equals 5 to 10 percent of what you weigh now. Why? You’ll see results right off the bat -- and not just on the scale. You’ll lower your cholesterol and blood pressure along with your risk of diabetes and heart disease. And if you already have one of these problems, a small loss will improve that, too.

Workouts Don’t Help That Much at First

Turns out that when you’re getting started, diet is what really drives weight loss. That’s because it’s easier to cut extra calories than to do the amount of exercise you'd need to burn them. As you lose weight, though, workouts help keep the pounds off and rev your metabolism.

Low Fat Diets Don’t Work

Butter and red meat are back on the menu, in moderation. Why? Doctors learned that cutting fat doesn’t always lead to weight loss and that fat in your diet doesn’t always lead to fat on your body. Your best bet: Aim for healthy fats most of the time.

High-Protein, Low-Carb Is Healthy

Your body uses more energy to digest proteins than it does fat or carbs. Proteins make you feel full longer. And they keep your blood sugar steady -- none of the spikes you get after eating carbs like white bread or a potato.

Eating More Fruits and Veggies Won’t Help

Broccoli alone won't budge the scale. Weight loss comes when you reduce calories across the board. It’s a balancing act, so you’ll need to load up on the green stuff and cut back portion sizes for other items.

Your Pants Size Matters More than Your BMI

Even people with a normal weight or BMI are more likely to have heart disease and diabetes -- and to die from them -- if they carry extra pounds around the middle. Doctors call this a high waist-to-hip ratio.

You Can't Be 'Fit and Fat'

Yes, you can be overweight and still run a 10K or do push-ups. Tests might even show that your heart and blood sugar levels are normal. But if the fat is around your waist, you're more likely to have health problems later on, like some cancers, diabetes, and heart disease.

It Has Nothing to do With Willpower

Obesity is a medical condition. We don’t overeat because we lack self-control. Our weight and eating habits have a lot to do with our body’s biology, genes, how we handle our stress and emotions, and what types of food we can afford. Hormones play a role. Obese people may not respond to leptin and other appetite control hormones like everyone else does.

Weight Loss Surgery Can Cure Diabetes

Almost 80 percent of people with type 2 diabetes went into remission after weight loss surgery. Doctors aren’t completely sure why. It’s tied to shedding pounds but some people see a drop in blood sugar before they even leave the hospital. If you have a weight-related condition like high blood pressure, sleep apnea or asthma, the procedure may reverse it, too.

Reviewed by Brunilda Nazario, MD on January 08, 2015

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This tool does not provide medical advice. See additional information: Disclaimer

© 2015 WebMD, LLC. All rights reserved.

People in the U.S. eat more calories than any other country.

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The correct answer is: Testicular

The U.S. isn't in the lead, but it is right up there -- we come in third with 3,680 calories consumed each day.

Patients ... just don't realize that their obesity is not under their control, that it's a disease." -Caroline Apovian, MD, Boston Medical Center