CHICAGO (CBS) — A Northwestern University researcher says the current generation of adolescents is the unhealthiest in U.S. history.

As WBBM Newsradio’s Regine Schlesinger reports, Dr. Donald Lloyd-Jones of the Feinberg School of Medicine at Northwestern says his study followed 5,547 children and adolescents between the ages of 12 and 19.

LISTEN: WBBM Newsradio’s Regine Schlesinger reports

He found more than one in three to be overweight and obese.

The study also found that many of the youngsters have high blood sugar levels, have a “lousy” diet, don’t get enough physical activity, and even smoke cigarettes.

The youth represent a sample of 33.1 million children and adolescents in the United States from the National Health and Nutrition Examination Surveys conducted from 2003 to 2008.

“Cardiovascular disease is a lifelong process,” Lloyd-Jones said in a Northwestern news release. “The plaques that kill us in our 40s and 50s start to form in adolescence and young adulthood. These risk factors really matter.”

None of the youngsters’ diets met the five criteria for being healthy. They had too much sodium and too many sugary beverages, and lacked fruits, vegetables, fiber and lean proteim.

“They are eating too much pizza and not enough whole foods prepared inside the home, which is why their sodium is so high and fruit and vegetable content is so low,” Lloyd-Jones said in the release.

The high blood sugar problem, which affected more than 30 percent of boys and more than 40 percent of girls, can lead to type 2 diabetes. About 25 percent of the survey respondents had smoked within a month of being surveyed.

While 52 percent of boys had an ideal level of physical activity, only 38 percent of girls did.

The effects of worsening teen health are already being seen in adults, with an increase in deaths from cardiovascular disease among adults ages 35 to 44 for the first time, particularly in women, the doctor said.

“We are all born with ideal cardiovascular health, but right now we are looking at the loss of that health in youth,” Lloyd-Jones said in the release. “Their future is bleak.”