Factors associated with overweight or obesity in children under five years old: a rapid review

Background and Context

This work was requested by the Welsh Government to help inform a strategy called Healthy Weight: Healthy Wales. The review may also help others involved in children’s health.

Over a quarter of children in Wales, aged four to five years old, are living with overweight or obesity. These children may have health issues during their childhood or adolescence, or both. They are also more likely to live with overweight or obese as adults, which can cause health problems.

A large number of things (factors) that could cause child overweight have been identified by research. These factors could be genetic (e.g. Prader-Willi Syndrome), psychological (e.g. stress, mental health), environmental (e.g. barriers to physical activity, healthier foods) and societal (e.g. lifestyle, influence of friends).

Aims of this research

Studies prior to this have already found evidence of factors that contribute tochild overweight or obesity. However, these reviews looked for factors across a wide range of children’s ages. There are no up-to-date reviews that look at these contributing factors specifically in children under five years of age.

Methods

The researchers identified and summarised existing reviews of research evidence. They also looked at the strength (certainty) of the evidence. They looked for evidence about factors that could be associated with overweight or obesity in children under five years old. They included research evidence available up to December 2023, and they identified 30 *systematic reviews. (*A systematic review identifies all relevant research studies, assesses their quality, summarises the evidence, and uses reproducible methods).

Results

A wide range of factors were found to be associated with an increased risk of overweight and/or obesity in children under 5 years old. There were also some factors linked to a decreased risk of child overweight and/or obesity. The evidence quality ranged from being strong or medium, to being poor or not available.

Policy and Practice Implications

The strong (high-certainty) evidence shows that there are certain things that could support children to have a healthier weight. Two examples are:

1. helping women living with overweight (who are thinking about, or trying to get pregnant) to lose weight, and
2. providing opportunities for children of working mothers to eat healthier foods and be more physically active.

There is also some moderate evidence about other things, which may help. Examples include promoting breastfeeding, reducing consumption of sugary drinks, and supporting the child’s caregivers to give children them healthier foods and opportunities to be active.

Important to note

The findings from this review may differ from other reviews. One of the reasons is that this review only reports on overweight or obesity in children under the age of five. The review also highlights where more research is needed.

For more information and to read the full review, click here.