Obesity and associated cardiovascular risk factors are highly prevalent in youth and are associated with early morbidity and mortality. Changing health behaviours is effective in reducing risk factors, but challenging to implement. The Living Green and Healthy for Teens (LiGHT) app has been rigorously developed as an evidence-based, user-friendly, stakeholder-reviewed tool to facilitate healthy behaviour change.

Primary Research Question
Among youth aged 10-15 years, does randomization of their family to the use of the interactive gamified Living Green and Healthy for Teens (LiGHT) app over a 1 year period, compared to a simple listing of healthy lifestyle information websites, increase the proportion of youth engaging in a composite of healthy active living behaviours?

Secondary Research Questions
Does the LiGHT app:
a) prevent an increase in BMI z-score at 1 year;
b) increase time spent in moderate to vigorous physical activity at 1 year; and
c) improve diet quality at 1 year?

Using a single-centre randomized, parallel, controlled single-blind design, 500 376 eligible youth-parent dyads will be allocated 1:1 to received: a) the LiGHT app system; or b) a list of links to websites providing information and tips on healthy eating and activity. They will be followed for 2 years. All families with at least one smart phone will be eligible. App usage will be monitored electronically. Visits at 6 months, 1 and 2 years will evaluate questionnaires on food frequency, breakfast intake, and screen and sleep time, as well as 1 week accelerometry data to quantify moderate and vigorous physical activity and sedentary time. The cohort from which many of the youth and parents will be drawn has already demonstrated a commitment to long-term follow-up.

The team is composed of individuals from McMaster University and the Childhood Obesity Foundation, who respectively have expertise in: recruitment, retention and high quality data collection among cohorts of youth, as well as successful completion of large randomized trials; and development, evaluation and community-based implementation of behavioural interventions including electronic tools for obesity treatment and prevention in partnership with industry and government.

Many health apps are either not developed based on evidence or are not engaging for users, and very few are studied systematically for their effectiveness in improving health, especially among youth. This trial will evaluate the fairly long-term use of an app that has been developed in Canada based on sound behavioural psychology, scientific evidence regarding behaviours relevant to cardiovascular health, and interactive, engaging technology. It further encourages family engagement and multiple motivators which are important for youth. We will learn whether a properly designed app can affect healthy behaviour change at a critical life stage, over a sustained period of time. If effective, wide dissemination on a population scale through simple electronic channels will facilitate improved cardiovascular risk profiles for any family with access to a smartphone.

Study Type

Interventional - Lifestyle

Study Design

RCT with an app

NO. of Countries


NO. of Sites


NO. of Participants


Study Period




CIHR Project Grant

Back To Top