Dr. Sarah Lester, a pediatrician from Andover, N.H., told ABCNews.com she lost 30 pounds, setting a good example for her patients' families.
"I do think it makes a big difference," said the 38-year-old. "Many ask me how I did it and when I tell them more exercise and eating less many are disappointed. However when they hear even for me there isn't a magic bullet, I think it helps."
New CDC data show that compared with whites, African Americans have a 51 percent higher prevalence of obesity and Hispanics have 21 percent higher obesity prevalence.
Some say that as an African American, Benjamin could set a better example.
"It is important to 'walk the walk and not just talk the talk,'" said James Anderson, a professor of medicine and clinical nutrition at University of Kentucky Medical Center. "Oprah struggles as a role model and has given up, as I understand it. Rumor has it that President Obama still smokes. We need role models who are attempting to be leaders for change in health and lifestyle to be role models."
But other top health professionals argue that one can be fit and fat.
"I thank God that Dr. Regina Benjamin is a fat woman," said Joanne Ikeda, a nutrition specialist at the University of California, Berkeley. "Maybe now we will stop making the assumption that all fat people are unhealthy particularly in light of new data coming from the National Health and Nutrition Examination Survey."
Data from that survey show that more than half of so-called overweight people are metabolically healthy, compared to one-quarter or about 16.3 million adults 20 years or older, who are "metabolically abnormal."
The study emphasizes looking at a person's metabolic health -- blood pressure, cholesterol, inflammation and sugar level indicators -- as a better diagnostic tool for future health problems.
"I am appalled that this amount of bias and discrimination exist regarding large people," said Steven Blair, professor of exercise science at Arnold School of Public Health, University of South Carolina. "The focus should be on Dr. Benjamin's credentials and accomplishments. What difference does her size make?"
The former CEO of the Cooper Institute agreed that it is impossible to determine from a photo whether someone is eating a healthy diet or exercising regularly, the cornerstones of physical fitness.
"I cannot resist stating that although too many people assign all sorts of bad traits to overweight/obese people, from being lazy, poor workers, I can think of some pretty bad characters who are thin," he said.
Blair, who told ABCNews.com that he is also overweight, said "even people who are obese are themselves biased."
That negative stereotype even colors national research, which puts an emphasis on caloric intake rather than energy expenditure, according to Blair.
"Should the face of public health practice a healthy lifestyle?" he asked. "Yes, she should not smoke or engage in other unhealthy behaviors and not exercise. I have been harping on this for the last 10 to 15 years. Let's focus on healthful behaviors instead of the way they look."
But Dr. Otis Brawley, chief medical officer for the American Cancer Society, and an African American, said there may be "some discrimination people don't realize."
"Obesity has a huge environmental component and is rooted in how one is fed in childhood and what physical activities you partake in the inner city," he told ABCNews.com.