One Simple Swap: Afterschool Program Helps Children Achieve Healthier BMI Scores

Childhood obesity remains one of the most stubborn public health challenges in the United States. While the adult obesity rate appears to be slowing, nearly one in five school-aged children is affected by obesity, a figure that has remained historically high despite decades of clinical guidance, school wellness policies, and public awareness campaigns. Many interventions have tried to tackle the problem by urging children and their families to change multiple behaviors at once—exercising more, eating better, sleeping longer—but such multi-component programs are often difficult to implement at scale and unrealistic for families to sustain over time. A new randomized controlled trial led by researchers at Boston University School of Public Health suggests that a far simpler strategy, focused on a single dietary change, can meaningfully shift children’s weight trajectories in a healthier direction.

The study, published in JAMA Network Open, evaluated a community-based behavioral intervention called H2GO!, which was designed to reduce children’s consumption of sugar-sweetened beverages and encourage them to drink more water. Over a 12-month follow-up period, children who participated in the intervention showed a significantly greater reduction in their body mass index z-score, or zBMI, compared with peers at comparison sites. The zBMI measure is a standard tool in pediatric research because it tracks BMI in growing children while accounting for age and sex, allowing researchers to assess whether a child’s weight status is improving or worsening relative to growth expectations rather than relying on raw BMI numbers alone.

Why focus on sugary drinks? Sugar-sweetened beverages, including regular sodas, fruit-flavored drinks, sports drinks, and energy drinks, are the largest source of added sugars in children’s diets. These liquid calories carry a particular metabolic liability: they do not produce the same sensation of fullness as solid food, so children who consume them tend not to compensate by eating less at their next meal. The result is an excess of total daily calories that can drive weight gain over time and raise the risk of developing type 2 diabetes, cardiovascular disease, and dental decay. Because beverage consumption patterns are established during formative life stages, and because intake remains stubbornly high among children and adolescents, sugary drinks represent an attractive and concrete target for prevention.

The intervention was delivered at Boys & Girls Club sites across Massachusetts, an organization that serves more than four million school-aged youth nationwide through academic, social, and leadership programming at roughly 5,500 locations. Trained club staff led 12 in-person group sessions with 437 children ages 8 to 13, each participating alongside a parent or caregiver. The six-week program, conducted in multiple waves between 2020 and 2025, blended interactive education with youth engagement: children took part in taste tests and sugar measurement demonstrations that made the hidden sugar content of common drinks visible and tangible, created print, music, and video projects explaining why drinking water mattered to them personally, and completed take-home activities with their parents to reinforce the message outside the club.

The study population reflected the communities that bear a disproportionate share of the childhood obesity burden. More than two-thirds of participating children qualified for free or reduced-price lunch, and more than half identified as Hispanic or Black. These communities are more likely to face structural barriers to maintaining a healthy weight, including economic constraints, neighborhood and environmental conditions that limit access to affordable healthy foods and safe opportunities for physical activity, and unequal access to preventive healthcare. The research team deliberately designed H2GO! to work within a trusted youth-based setting where children already develop everyday habits, rather than expecting families to seek out clinical services or navigate unfamiliar systems.

That design philosophy grew out of the team’s formative work with families and community partners. Corresponding author Dr. Monica Wang, associate professor of community health sciences at Boston University School of Public Health, who co-led the study with Selenne Alatorre, a senior research project manager at BUSPH at the time of the study, explained that asking families to change many dietary behaviors at once can quickly become overwhelming, particularly for those facing competing time and financial pressures. It is also difficult for a child, or an adult, to simply choose differently when sugary drinks are everywhere in the environment. The team focused instead on one simple, concrete change that did not require a costly or complicated overhaul of family life: drink fewer sugary beverages and more water.

The results at the 12-month follow-up were striking. At the start of the study, children consumed an average of 12 ounces of sugar-sweetened beverages and 24 ounces of water per day. By the end of the follow-up period, children who received the H2GO! intervention reported reducing their daily sugary drink intake by an average of 3.6 ounces while increasing daily water consumption by an average of 6.6 ounces. In exploratory analyses, nearly 30 percent of participating children shifted to a lower BMI category over the 12 months, compared with 18 percent of children at comparison sites. Among children who began the study with overweight, 44.4 percent of those in the intervention moved into the healthy-weight category, compared with 31.6 percent at comparison sites, and fewer progressed to obesity, at 5.6 percent versus 21.1 percent. Among children who began with obesity, 47.5 percent of those in H2GO! moved to a lower BMI category, compared with 36.7 percent at comparison sites.

Dr. Wang described one of the most striking findings as the ability to shift participants’ BMI in a healthier direction at a time when national childhood obesity trends were moving the opposite way, a signal that well-designed, community-based behavioral interventions can make a meaningful difference even against a difficult broader backdrop. The results also reaffirm that improving children’s health happens far beyond the pediatrician’s office. Community organizations, she noted, are critical partners in prevention because they are where children spend time, build relationships, and learn from one another. Embedding evidence-based health programming in settings children already trust may be one of the most practical routes to reaching families who face the greatest barriers to clinical care.

The trial builds on an earlier H2GO! pilot study conducted over six months at two Boys & Girls Club sites from 2016 to 2017, which also produced lower zBMI scores and reduced sugary drink intake among participants. The latest multi-site randomized controlled trial expanded the approach across the Commonwealth of Massachusetts, demonstrating that the community-tailored model is both effective and scalable. The intervention culminated in a community event where children showcased the work they had created and the lessons they had learned, reinforcing ownership of the health messages they had crafted themselves. The study was funded by the National Institute of Diabetes and Digestive and Kidney Diseases and coauthored by researchers at Boston University School of Public Health, Harvard T.H. Chan School of Public Health, Boston Medical Center, the University of Connecticut School of Social Work, the Massachusetts Alliance of Boys & Girls Clubs, and the University of Massachusetts T.H. Chan School of Medicine.

The researchers are careful to note the limitations of the work. Measurement differences and reliance on self-reported sugary beverage and water intake mean that more research is needed to understand whether additional factors may have contributed to the observed changes in children’s BMI trajectories. Future studies, the team says, should explore how this type of intervention could be delivered in other community settings and applied to other dietary behaviors, such as the consumption of ultra-processed foods. Still, the central message is an encouraging one for public health: large-scale policy and environmental changes remain essential, but communities do not have to wait for them to make progress. By giving children and families practical tools to make healthier choices within the environments they live in now, programs like H2GO! demonstrate that acknowledging structural barriers and strengthening the agency that families and communities already have can go hand in hand—and that sometimes the most powerful intervention is also the simplest one.

Subject of Research: A community-based behavioral intervention reducing sugar-sweetened beverage consumption and body mass index in school-aged children

Article Title: Afterschool-based intervention helps steer children toward healthier BMI scores

Article References: Afterschool-based intervention helps steer children toward healthier BMI scores. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: childhood obesity, sugar-sweetened beverages, BMI z-score, randomized controlled trial, afterschool programs, Boys & Girls Clubs, water consumption, behavioral intervention, public health, health equity, pediatric nutrition, JAMA Network Open