Cardiovascular risk factors and obesity are highly prevalent in youth. Changing health behaviours is effective in reducing risk factors, but challenging to implement. One possible solution is an interactive smartphone app system for healthy behaviour change that is evidence-based and user-friendly.

Research Questions
Among youth aged 10-16 years and a parent, does randomization to the use of one of two Living Green and Healthy for Teens (LiGHT) apps over a 1 year period affect the proportion of youth with healthy active living behaviours, and healthy body size?

Using a single-centre randomized, parallel, controlled single-blind design, 250 eligible youth-parent dyads will be allocated 1:1 to receive one of two apps that provide information and tips on healthy eating and activity in different ways. They will be followed for 1 year. All families with at least one smartphone or tablet will be eligible. App usage will be monitored electronically. At the beginning, and 3 months and 6 months after starting, youth and parents will complete questionnaires (health, food intake, and activities including screen time) and body measurements, and youth will provide a urine sample and complete fitness tests and 1 week of accelerometry monitoring to quantify moderate and vigorous physical activity, sedentary time and sleep time. At 1 year participants will be asked to complete an online questionnaire.

For this project, we have teamed up with the Childhood Obesity Foundation, who have expertise in the development, evaluation and community-based implementation of behavioural interventions including electronic tools for obesity 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. Through this trial, 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.

Questions? Email

Download LiGHT study recruitment poster (PDF)
Study Type

Interventional - Lifestyle

Study Design

RCT with an app

NO. of Countries


NO. of Sites


NO. of Participants


Study Period

2019 - 2023



CIHR Project Grant

Childhood Obesity Foundation

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