Study shows benefits of Healthy Harlem programme

Mathematica Policy Research posted a new research brief that summarises findings from a study of Healthy Harlem, an after-school programme aimed at promoting healthy lifestyles. The study, by James Mabli, Martha Bleeker and Mary Kay Fox, showed that participation in the Healthy Harlem programme led to increased physical activity and improved weight status for overweight and obese pupils.

Key components of Healthy Harlem include physical activity, healthy snacks, nutrition education lessons and parent workshops. To assess Healthy Harlem’s effectiveness, the authors monitored pupils at 21 after-school sites during an initial baseline year and then measured programme impacts after two and three years of participation. They collected data through a pupil survey, a fitness test and direct measurements of height and weight. Key findings were as follows:

  • A 5.5 percent decrease in mean BMI z-scores after two years of participation and a 9.0 percent decrease after three years of participation. According to the report, a BMI z-score reflects the number of standard deviations a pupil’s BMI is from the mean BMI for a reference population.
  • A decrease of 12.2 percentage points in the percentage of pupils who were overweight or obese after two years, and a decrease of 18.4 percentage points after three years.
  • An increase in the percentage of pupils considered to be within the Harlem Fitness Zone, a measure of fitness based on a pupil’s ability to complete a minimum number of laps, defined for age-and-gender subgroups.

Source: The impact of Healthy Harlem on the body mass index and weight status of adolescents after two and three Years (March 2018), Mathematica Policy Research

Can schools help prevent childhood obesity?

A study published in The BMJ tests the effectiveness of a school and family based healthy lifestyle intervention (WAVES) in preventing childhood obesity.

Almost 1,500 pupils, aged five- and six-years-old, from 54 primary schools in the West Midlands took part in a randomised controlled trial of the WAVES programme. The twelve-month intervention encouraged healthy eating and physical activity, and included an additional 30 minutes of daily physical activity at school and a six-week programme with a local premiership football club.

Children’s measurements – including weight, height, percentage body fat, waist circumference, skinfold thickness and blood pressure – were taken when they started the trial. These measurements were taken again 15 months and 30 months later and were compared with children in a control group.

At the first follow-up at 15 months, the mean body mass index (BMI) score was not significantly lower for the intervention group compared with the control group. At 30 months, the mean difference was smaller and remained non-significant. The results suggest that schools alone may not be effective in preventing childhood obesity.

Source: Effectiveness of a childhood obesity prevention programme delivered through schools, targeting 6 and 7 year olds: cluster randomised controlled trial (WAVES study) (February 2018), BMJ 2018; 360:k211

Teenage onset obesity linked to school dropout

A new article in the Journal of School Health has shown that becoming obese during early adolescence increases the risk of school dropout.

Data on 5,066 children was obtained from the 1979 National Longitudinal Study of Youth, a longitudinal project that follows a sample of people in the US born between 1957 and 1964. Each wave of assessment included participants’ obesity status (BMI) and school enrollment status.

The study identified four trajectories of obesity from ages 6 to 18: (1) A non-obese group, (2) a chronically obese group with individuals who were obese in both childhood and adolescence, (3) decreasing trajectory (childhood-only obesity), and (4) increasing trajectory (adolescent-onset obesity). Adolescents belonging to the increasing trajectory group (adolescent-onset obesity) had a higher likelihood of dropping out of high school compared with those belonging to the other three groups.

The authors conclude that adolescent-onset obesity is a unique contributor to school failure. Although the reasons for this are unknown, they suggest that the high significance placed on social status during early adolescence combined with significant physiological changes as a result of puberty may have an especially adverse impact on those becoming obese during this transitional period. They also suggest that becoming obese during adolescence (as opposed to childhood) may be a disadvantage due to having less time to develop adaptive coping strategies.

The study also showed ethnicity playing a significant role, with white teenagers who become obese during adolescence particularly vulnerable to school dropout. The report suggests this may be explained by greater social stigma being placed on white versus African-American or Latino adolescents becoming obese.

Source: Is Obesity Associated With School Dropout? Key Developmental and Ethnic Differences (2015), Journal of School Health, 85(10).