Key messages

• Multi-component treatment approaches (addressing diet, physical activity, and/or other behaviours) slightly improved the physical well-being and body mass index (BMI) z-score (a score showing whether someone's weight is higher or lower than what’s typical for people of the same age and sex) of adolescents (aged 10 to 19 years) at two years. These treatments had limited overall effects on adolescents' mental well-being, physical activity, quality of life, and BMI z-score (at 12 months).

• The overall benefits and risks of multi-component treatments for adolescents remain uncertain, and most evidence in this review comes from high-income countries.

• More studies are needed in different populations and locations, to understand what works and what does not work for different adolescents.

What is the problem?

Obesity in adolescents is a global health challenge with many causes, including diet, physical activity, and behaviour. Obesity in adolescents is usually defined as having a body mass index (BMI – a number calculated from a person’s height and weight to check whether their weight is in a healthy range) that is much higher than what is typical for young people of the same age and sex. Treatment approaches that encourage healthier habits are often used to manage obesity in adolescents, but their long-term impact remains unclear.

What did we want to find out?

We wanted to determine if multi-component treatments promoting better diet, physical activity, and behaviour help adolescents (aged 10 to 19) living with obesity. We focused on how these treatments affect physical and mental well-being, quality of life, physical activity, and weight-related measures over the long term (follow-up of 12 to 24 months).

What did we do?

We searched for studies that tested treatments combining two or more areas: diet, physical activity, or behaviour change. We included only studies comparing these treatments to no treatment, usual care, or a waiting-list group. All studies had to have followed up the adolescents for at least one year from the start of the intervention. We compared and summarised the results of the studies and rated our confidence in the evidence, based on factors such as study methods and sizes.

What did we find?

We found 33 studies involving 5949 adolescents in primarily high-income countries, conducted in places like schools, churches, healthcare facilities, and community centres. We divided the studies into two groups: (1) healthcare-based studies delivered treatments in healthcare facilities such as primary care treatment centres or hospitals; (2) community-based studies delivered treatments in schools, community centres, sports centres, or other public spaces.

Main results

Compared to usual care, healthcare-based multi-component treatment approaches may make little to no difference to adolescents':

• physical or mental well-being;

• physical activity when measured as a change-from-baseline score (a score showing how much a person’s physical activity increased or decreased after the treatment programme compared with how active they were at the start);

• BMI z-score.

We do not know if these treatments have an effect on adolescents' physical activity levels when these are measured as a final score. These treatment approaches may slightly improve adolescents' quality of life. We are very uncertain if they led to any harmful or unwanted events. None of the studies that assessed healthcare-based approaches reported on obesity-associated disability.

Compared to usual care, community-based multi-component treatment approaches may:

• slightly improve adolescents' physical well-being;

• make little to no difference to their mental well-being and physical activity levels;

• make little to no difference to BMI z-score in the shorter term (12 months) and may reduce BMI z-score slightly in the longer term (24 months).

These treatments probably make little to no difference to adolescents' quality of life at 12 months. None of the community-based studies reported on obesity-associated disability or whether the treatment approaches led to any unwanted or harmful events.

What are the limitations of the evidence?

We have little confidence in the evidence because the studies had limited long-term follow-up and limitations in their methods. Most were conducted in high-income countries, so we cannot be certain how well these interventions might work elsewhere and in different populations.

How current is this evidence?

The evidence is current to February 2024.