Over the years, Robert Kushner has seen many obese patients get "tripped up" trying to keep pounds off because they rely on fast food, juggle too many tasks and dislike exercise.

So Kushner, an obesity expert, began helping patients plan diet and physical activity around their lifestyles and habits.

"We don't necessarily put people on any specific diet; it really gets to what is their life, what are their struggles," he said. "We believe obesity care can't be inconsistent with culture, family or how you lead your life."

He recently suggested that a patient split meals with his wife when they dined out, rather than each having large portions or avoiding restaurants entirely. When the man said he was uncomfortable sharing a meal with his wife when the couple was out with friends, Kushner said to do it anyway.

"I said, 'It's a strategy that works whether you're with other people or not. . . . Be assertive,' " said Kushner. "I think people don't think about it because they just aren't raised to share."

The patient kept track of the foods he was eating, learning to avoid larger portions and fattening dishes. He has lost 15 pounds in six months, cutting about 500 to 700 calories per day.

More than a third of U.S. adults are obese, according to a 2015 report from the Centers for Disease Control and Prevention.

Kushner, who directs the Center for Lifestyle Medicine at Northwestern Medicine in Chicago, said he realized in the 1980s that obesity was a looming problem. He started combining diet, nutrition, exercise and behavioral changes into a plan for patients.

Since then, "what's changed is the maturity of the area, understanding more about the effects of stress and sleep on body weight, and some of the behavioral-change techniques have expanded," he said.

In addition to promoting good sleep habits and stress management techniques such as meditation, Kushner and his colleagues suggest bariatric surgery for patients with a body mass index of 40 or more and for some who are less obese but who have medical problems such as Type 2 diabetes, sleep apnea and heart disease. They also recommend medication for patients with BMIs as low as 30 who have additional medical problems or have failed to lose weight despite lifestyle changes.

While studies haven't generally proved that lifestyle changes are effective for weight loss, Kushner said patients often have trouble shedding pounds unless problems like stress are managed.

Kushner's approach proposes gentler, moderate changes. Rather than tell patients to cut out every unhealthy food they love, Kushner suggests focusing on alternatives with higher fiber and water content but fewer calories. (Think beans, vegetables, salads, fruits, broth-based soups and whole grains such as oatmeal.)

For the couch potato who finds exercise overwhelming, Kushner advises walking for short periods, building up to three 10-minute brisk walks daily to "boost your energy level and mood while you also burn calories."

He also suggests that dog owners walk their pet for 30 minutes daily rather than leave Fido in the back yard. Kushner found that dog-walking helped overweight and obese people lose weight in a study, and he wrote a book about it - "Fitness Unleashed!: A Dog and Owner's Guide to Losing Weight and Gaining Health Together" - with veterinarian Marty Becker.

"I call it an exercise machine on a leash," Kushner said. "It is a way for people to think about moving their body around in a fun way."

Most of his patients lose about 10 percent of their body weight (some more than 20 percent) after six months and keep it off during the program, Kushner said.

"Patients say they feel understood and more motivated as they are given personalized direction to make positive changes in their lifestyle," he said.

Kushner created a questionnaire to screen patients for traits that prevent weight loss - such as eating what's convenient rather than planning healthy meals or having an all-or-nothing mentality - traits that Kushner and colleagues found in a study to be strongly linked with obesity.

"Once you take the quiz and know your factor type, I can personalize a plan to help you lose weight and keep it off," Kushner said.

Another way Kushner hopes to help patients tackle obesity is by teaching medical students about treating and preventing it. He found in a recent study that the U.S. Medical Licensing Examination was focusing much more on diagnosing and treating obesity-related illnesses, such as Type 2 diabetes and sleep apnea, than on how to counsel patients on diet, physical activity, behavior changes, the use of medications and bariatric surgery.

But Kushner said his approach isn't only about weight loss.

"We know that as little as 5 to 10 percent weight loss will improve the health and well-being of individuals and can also improve blood sugar, blood pressure, the fats in your blood, arthritis or reflux symptoms, as well as your mood and energy level."