Studies have shown that most overweight individuals have a hard time estimating their weight problem.

In fact, 70 percent of obese people in the United States think they are merely overweight, a new poll shows. Thirty percent of overweight people said their weight was normal, and 39 percent of morbidly obese participants (those who were 100 pounds or more overweight) said they were simply overweight.

How did the perspectives of so many become so skewed?

Researchers theorize that this gap between reality and how people perceive themselves – and their loved ones – comes from a tendency to assume that carrying some extra weight is "normal," leading many people to underestimate their weight problems, according to the National Institutes of Health (NIH).

"While there are some people who have body images in line with their actual BMI [body mass index], for many people they are not, and this may be where part of the problem lies," Regina Corso, vice president of Harris Interactive, the company that conducted the new poll, said in a statement.

"If they do not recognize the problem or don't recognize the severity of the problem, they are less likely to do something about it," Corso said.

The poll included 2,418 respondents who gave their height and weight, then calculated their BMI, a ratio of weight to height, in an online questionnaire. Participants were then asked to select a category of weight that they thought they fell into.

Other obesity experts believe that people fail to view their weight realistically because of the stigma associated with being overweight and obese, George Blackburn, chair in nutrition medicine at Harvard Medical School in Boston, told Life's Little Mysteries.

In another study, parents were found to misclassify their childrens' weight problems. Half of mothers and 39 percent of the fathers said that their obese four- or five year-olds were normal weight; 75 percent of mothers and 77 percent of fathers thought that their overweight child was normal weight, according to the results of an 800-parent survey published in the February issue of the journal Acta Paediatrica.

When asked to choose their child's body shape from seven different sketches, 95 percent of the overweight children's parents chose a slimmer sketch than the data they provided about their child indicated. The parents of normal weight children had similar results, with 97 percent choosing a slimmer sketch, according to the study, which was conducted by researchers from the University Medical Centre of Groningen in the Netherlands.

Those unsure of how much weight they need to lose in order to fall into a healthy BMI category should be evaluated by a medical professional, according to the NIH. Nutritionists and doctors can customize safe weight-loss plans for overweight or obese individuals.

This article was provided by Life's Little Mysteries, a sister site to LiveScience.