"At the end of the day, we still have the law of energy balance to contend with," he said. "If you ingest more than you expend you are going to gain weight, period."
Dhurandhar conceded that eating and exercise play a significant role in obesity, but said that role is not as well understood as the general public thinks.
"We've focused almost all our resources on the so-called 'Big Two' of diet and exercise for more than 50 years and it hasn't helped," he said. "We will have to move beyond 'eat less and move more' if we want to make progress."
Ochner said he agreed that trying to lose weight and keep it off in the long term by exercising and cutting back on calories has less than a 1 percent chance of succeeding. He acknowledged that the reasons for weight gain vary greatly for each individual and the precise formula for energy balance through diet and exercise is nearly impossible to determine.
"There is literally, there is no difference between an emaciated person starving to death and an obese person on a healthy weight loss diet in terms of physiological reactions," he said. "That is going to be a tough problem to solve."
So what do you think? Do you believe obesity comes down to personal responsibility or are there other factors at play that thwart weight loss efforts? Share your thoughts in the comments section below. Better yet, voice your opinion during today's obesity tweet chat at 1 p.m., ET.
Our ABC Health tweet chat is moderated by Dr. Richard Besser, ABC News' chief health and medical correspondent. The American Medical Association, The Obesity Society and the Robert Wood Johnson Foundation are among the health groups and distinguished experts joining the conversation on this important health topic. If you'd like to join in too, click here for more details.