Sept. 24, 2010 — Nearly a quarter of obese Americans say they have been diagnosed with depression, a significantly higher percentage than normal weight people, according to the latest Gallup-Healthways Well-Being Index.

The new survey also says that more than one in four American adults who are obese are considerably more likely than people who are a normal weight to report experiencing negative feelings of stress, worry, anger, and sadness.

The survey finds that 23.2% of obese adults report having been diagnosed with depression, compared to 14.9% of people who are overweight, 14.3% of people of normal weight, and 19.1% of underweight people.

The report also says that:

• 41.6% of obese people feel stressed, 34.5% say they worry, 15.7% report they feel angry, and 19.9% experience sadness.
• 37.4% of overweight people feel stressed, 29.5% worry, 13.1% feel angry, and 15.8% suffer from sadness.
• 39.4% of people of normal weight feel stressed, 30.6% worry, 12.6% experience anger, and 16.3% report sadness.
• 42% of people who are underweight say they feel stressed, 35.9% worry, 16% feel angry, and 21.3% experience sadness.

The findings were based on more than 250,000 interviews between January-September 2010.

Classifications Based on Body Mass Index

Gallup calculates body mass index scores based on survey respondents’ self-reports of height and weight. BMI values of 30 or above are classified as obese, 25.0-29.9 as overweight, and scores between 18.5 and 24.9 put people in the normal range. A BMI of less than 18.5 is classified as underweight.

Gallup says that “carrying some extra weight does not appear to have the same effect as being obese, as negative emotion levels among those who are overweight are about the same as among those who are a normal weight.”

Underweight People Also Feel Blue

Dan Witters, Gallup’s well-being scientist, tells WebMD in an email that many people who are underweight have eating disorders, which explains why there is a relatively high percentage of underweight depressed people, according to the survey.

“Anorexia and bulimia are both substantially linked to depression in both men and women, and anorexia is linked to suicide among women,” Witter says. “Sometimes — particularly among women — the depression comes first and the eating disorder comes second.”

Gallup notes that only about 1.7% of adult Americans are underweight.

Prevalence of Overweight and Obesity

Gallup says it classified 36.3% of Americans as overweight, based on respondent’s self-reports of height and weight, and 26.7% as obese. About 35% of adults are of normal weight.

Gallup says it’s possible that people who have been diagnosed as depressed may be more likely to become obese or feel stressed or worried.

“High levels of stress, worry, anger, sadness, and depression in particular decrease a person’s quality of life and can have an impact on his or her engagement in society and work,” Gallup says. “To add to the problem, the average number of Americans classified as obese is up to 26.7% so far in 2010, compared with 25.5% in 2008,” when the company first started tracking obesity levels.

With so many people obese, their decreased emotional well-being could prove costly in terms of productivity and health care costs, Gallup says.