Despite the growing evidence that America is packing on the pounds and the often-voiced health concerns about obesity, research suggests Americans aren't all that concerned.

In fact, a new report by the NPD Group shows dieting in the U.S. to be at an all-time low.

According to the group's 21st annual "Eating Patterns in America" report, even with those extra pounds, dieting has fallen out of favor, driven in large part by aging Baby Boomers, who are less likely than previous generations to follow a doctor-recommended diet.

While 60% of adults still say they would like to lose 20 pounds, NPD's research reveals that the percent of adults on a diet last year was at the lowest level in at least 16 years.

In 1990, a typical week throughout the year found that 35 percent of women and 26 percent of men were on a diet. Last year, those levels dropped to 26 percent of women and 19 percent of men on some kind of diet.

"Dieting is at an all-time low, despite more Americans being overweight than ever before," said Harry Balzer, vice president of The NPD Group and author of its 21st Annual Eating Patterns in America report.

NPD data shows that as Americans grow older, they are more likely to diet. The peak years for dieting are 55-64, which many Baby Boomers are now entering. However, individuals entering into this age group are less likely to be following a doctor supervised diet than previous generations. They are still using diets, but diets of their choice rather than one recommended or supervised by a doctor.

"It is not unusual for this Baby Boomer generation to set their own rules as to how they deal with dieting issues," Balzer said. "This is a time in life where health issues begin to creep into our lives and in the past, doctors provided advice that was followed on changing eating habits. It appears people in this age group today are either not getting -- or not listening to -- their doctor's advice. In fact, the number one diet in America is one that is called 'my own.'"

NPD Group compiles the annual report for the food and beverage industry, which uses it to to examine how Americans are really eating and drinking.

The report takes an in-depth look at the in-home and away-from-home food and beverage consumption habits, including trends in diet and nutrition, and concerns about health and food safety.