Gallup's annual Consumption Habits survey, conducted July 10-14, also found only 4-in-10 favor setting higher rates for those significantly overweight.
This may reflect that while 45 percent of the 2,027 U.S. adults in Gallup's July Consumption Habits survey said they were overweight, but only 19 percent said they currently smoked.
Twenty-eight percent of U.S. adults who have smoked in the last week said higher insurance rates for smokers were justified, compared with 65 percent of those who didn't smoked.
Thirty-four percent of U.S. adults who said they were overweight supported setting higher health insurance rates for those who were overweight, compared with 47 percent among those who considered their weight to be about right.
Forty-seven percent of Republicans were more likely than Democrats at 37 percent to say it is justifiable to have higher health insurance rates for people who are significantly overweight.
Republicans are also slightly more supportive than Democrats of setting higher insurance rates for smokers. Differences in smoking and weight status cannot explain these partisan differences: Democrats are 1 percentage point more likely to be overweight and to smoke than Republicans.
The margin of error for the total survey was 3 percentage points, while the sample of smokers has a margin of error of 6 percentage points.