Junxiu Liu does not do stand-up comedy.

But if you attended high school 20 or more years ago and consumed the nutrient-lacking, calorie-loaded lunches served back then, what the doctor who does medical research said to HealthDay Reporter Alan Mozes comes across as the bad punch line to a bum joke.

She said: “School is the healthiest place for Americans to eat right now.”

She didn’t say this to amuse. She said this to summarize a study she led as a postdoctoral student at the Friedman School of Nutrition Science and Policy at Tufts University in Boston. That study was published on JAMA Network Open on April 12.

Because it had never been done before, Liu and three colleagues set out “to investigate patterns and trends in diet quality by [specific] food sources.” So as they reviewed about 61,000 surveys completed by adults and children for the eight National Health and Nutrition Examination Surveys done between 2003 and 2018, they charted whether the foods consumed came from a grocery store; a restaurant, including all possible quick-service options like pizza shops and convenience stores; a school cafeteria; a worksite; or a miscellaneous source, everything from a gift from a friend to a snack from a food truck.

They graded the food choices as “poor,” “intermediate,” or “ideal” by using indices created by the American Heart Association and the federal government. In their review of the final survey from 2017-2018, the researchers found “modest improvements” in the foods consumed from grocery stores, “small improvements” in the restaurant meals, and “a worsening diet quality for the foods consumed from other sources.”

Except school cafeterias.

The improvement there was deemed “significant.”

In the 2003-2004 survey, 55.6 percent of the school cafeteria food consumed was graded as “poor.” By the 2017-2018 survey, the percentage of consumed foods receiving that rating plummeted 21.2 points to 24.4 percent.

Because this was the lowest poor-food percentage of any food source in the most recent survey, Liu told Mozes that schools are “the healthiest place for Americans to eat right now,” creating the sort of news that should make one former First Lady feel at least three times finer than expensive china.

Michelle Obama spearheaded the “Healthy, Hunger-Free Kids Act” of 2010. That legislation allowed the United States Department of Agriculture, according to their website, “to make real reforms to the school lunch and breakfast programs for the first time in 30 years,” reforms that eliminated many poor food choices from school menus.

But now’s no time to contemplate Michelle Obama’s emotional state. It’s time to consider the bad news behind the good news about school food - and if that bad news pertains to you.

The American Heart Association index that Liu and her colleagues used creates an overall assessment for each food and each food source. A mean score of 80 and above is considered “ideal”; under 40 percent, “poor.”

The average score for restaurant foods consumed by adults in the last survey is 29 percent, 11 percent below the middle-of-the-road “intermediate” range - and 51 percent below “ideal.” The average score for adults consuming grocery store foods is 38.3 percent, a better number you’d think - unless you think as I do.

How can anyone’s yearly grocery store score not add up to be “ideal”?

After all, you make the purchases. You have unlimited options. (My go-to grocery store, for instance, offers more than 100 different cereals.)

You can obtain any and every relevant piece of nutritional information via the internet. (If you don’t have the internet at home, you can access it at your local library.)

And while the nutritional improvement in school cafeteria food is certainly news, the too-often end result of the average American diet isn’t.

Obesity.

In a 2020 report, the National Center for Health Statistics listed the U.S. obesity rate at 42.4 percent. According to the U.S. National Institute for Diabetes, Digestive and Kidney Diseases, here’s the list of health woes that can accompany or follow excessive weight gain: type 2 diabetes, heart disease, high blood pressure, stroke, fatty liver disease, sleep apnea, arthritis, and gall bladder disease.

Now in the name of journalistic integrity, I feel the need to amend a previous statement. There is news about the obesity that so often results from the typical American diet.

It increases the adverse effects of COVID-19. Significantly.

A study that can be accessed online in Morbidity and Mortality Weekly Report found the chance of hospitalization and death increased in those who had contracted COVID-19 and were obese. And when in need of hospitalization, those with a body mass index of 45 or above (usually an indication of severe obesity) were 108 percent more likely to need mechanical ventilation.

Worse, the severely obese had a 61 percent greater chance of dying from COVID-19 than people with a healthy BMI.