Dr. Terry Bennett believes in being honest with his patients, but one woman was so offended about the way he spoke to her about her weight, she filed a complaint with the state Board of Medicine.
The New Hampshire state attorney general launched an investigation, asked Bennett to take a medical education course and admit he has made a mistake.
Bennett refused to take the course and says he is outraged by the investigation.
"Part of my job is to tell you the truth," Bennett said. "You come in here, you pay $75 to sit on the couch. I'm not going to sit here and talk about the weather with you. If you're noticeably obese, I know that you are going to have future health problems."
Obesity increases the risk of serious chronic diseases such as diabetes, heart disease, some cancer and arthritis and is a contributing factor in many deaths, according to the Centers for Disease Control and Prevention.
"They're trying to define me as a disruptive physician because I told somebody the truth," Bennett said.
The case has some medical professionals concerned.
"We are really walking on thin ice when we have the legal system coming into a doctor's office and saying what we can or cannot do," said Dr. Mark Fendrick, a professor of medicine at the University of Michigan.
Obesity is a growing concern in the United States. A new report finds that every state in the nation except for Oregon is getting fatter.
Still, Bennett said he realizes it's a sensitive topic.
"If you go light, they don't hear anything," he said. "If you go heavy, you lose them. So you are running on a razor blade."
Melinda Haney, another one of Bennett's patients, was initially offended when he told her she needed to lose weight.
"I left the office, got in my car and decided I was never coming back," Haney said.
But Haney did come back, and with Bennett's help she has lost more than 150 pounds. She has organized a petition to support him.
"Dr. Bennett is protecting us," Haney said. "He's telling us the truth and helping us to live longer, healthier lives."
The New Hampshire board would not comment, but member Kevin Costin told The Associated Press, "Physicians have to be professional with patients and remember everyone is an individual. You should not be inflammatory or degrading to anyone."
Bennett said he regrets offending a patient and wrote her a personal letter of apology when he learned of the complaint. But Bennett still believes in being blunt with patients.
"My job is not to offend you," Bennett said. "It's to educate you and that's all I'm trying to do."