What Difference Does School Lunch Make?

Obesity rates among students may be reduced through stricter school lunch standards for nutrition

(RxWiki News) More and more research is pointing to children's access to food as a major influence on their nutrition and risk for obesity. School lunches are a big part of that access.

A recent study found that strict school lunch standards appeared to make a difference in obesity rates among students.

States with strict school lunch standards – exceeding the USDA standards – had fewer obese students eating school lunches than states without those strict standards.

These findings took into account the geographical differences of states by comparing students within each state to each other.

"Pack a healthy lunch for your child."

The study, led by Daniel R. Taber, PhD, of the Health Policy Center at the Institute for Health Research and Policy at the University of Chicago, aimed to see whether students' weights improved with stronger nutrition standards in schools.

The researchers included 4,870 eighth grade students across 40 states in their study. The students were divided according to whether they paid regular price for lunch, received a free or reduced lunch or did not eat a lunch from the school cafeteria.

The measurement for the study was the difference between the weights of students who ate lunch from the school cafeteria and the weights of students who did not eat a school cafeteria lunch.

Children's weights were measured using body mass index (BMI) and obesity status. BMI is a ratio of a person's height to weight and is used to determine whether a person is a healthy weight or not.

Normal weight is a BMI between 18.5 and 24.9. An overweight adolescent has a BMI of 25 to 29.9, and those with a BMI of 30 or higher are considered obese.

These differences between students were compared between the states whose meal nutrition standards were stricter than those of the US Department of Agriculture and the states where nutrition standards did not exceed USDA standards.

By conducting the study this way, the researchers could compare the students against others in the same state as well as across states. This study design allowed the researchers to understand the results without geographical differences in child obesity rates interfering with the results.

The researchers found that in states with standards higher than USDA's standards, the difference in obesity between students getting free or reduced lunches and those not eating school lunches was 12.3 percentage points smaller than the difference between the same groups in states without standards higher than those of the USDA.

The researchers also found the average BMI difference between these students was 11 units smaller in the states whose standards were higher than USDA standards.

The researchers had also gathered data through family questionnaires on the students' demographic information, household income and their nutrition behaviors.

These diet behaviors included how much fast food they ate, how often they bought sweet or salty snacks and how much sugar-sweetened beverages they drank.

These findings were taken into account in comparing the students who received a free or reduced school lunch and those who did not.

"There was little evidence that students compensated for school meal laws by purchasing more sweets, salty snacks, or sugar-sweetened beverages from other school venues (eg, vending machines) or other sources (eg, fast food)," the researchers wrote.

"Stringent school meal standards that reflect the latest nutrition science may improve weight status among school lunch participants, particularly those eligible for free/reduced-price lunches," they concluded.

Deborah Gordon, MD, a dailyRx expert who specializes in nutrition but was not associated with this study, said the higher lunch standards led to clear benefits for the students.

"In schools that exceeded USDA standards, those students who qualified for free lunch not only ate the lunch but were able to refrain from excessive indulgence in sweets and sodas from the 'food' machines located in the school," Dr. Gordon said. "Their reward was a lowered incidence of obesity, and presumably all the health benefits accruing from that."

Dr. Gordon said the school districts with the higher standards took the first steps toward offering healthier lunches.

"The wiser school districts sensibly increased fruits and vegetables and limited (though didn't eliminate) products containing trans fats," Dr. Gordon said. "The best news about this study is that health professionals are minding the details of what our children eat for lunch at school."

Some examples of the state laws for school lunches that were stricter than those of the USDA's guidelines from 1995 included "encouraging or requiring a specific number of fruits/vegetables," "...[ensuring] at least half of all grains sold/served were whole grains; reductions in products that contain trans fats; and/or restrictions on milk to 1% or skim milk."

These standards were, however, adopted by the USDA along with others in the most updated school meal policies instituted in 2012.

The study was published April 8 in JAMA Pediatrics. The research was funded by the Robert Wood Johnson Foundation and the National Heart, Lung and Blood Institute. The authors declared no conflicts of interest.

Review Date: 
April 8, 2013