Programs focused on parents are insufficient to prevent childhood obesity, according to a meta-analysis

The study is published in a highly prestigious scientific journal, with the highest level of evidence, which is meta-analysis. It covers behavioral intervention in parents with children under one year of age and analyzes whether it has an impact on body mass index at two years of age. The message is clear: addressing obesity with intervention alone leads to failure. Parent-focused intervention does not reduce weight over the years. We know that it is a complex disease in which it is important to take a comprehensive approach, not only in the family environment, but also in the social and biological environment. The family alone is not enough to prevent early obesity. Preventing obesity from the cradle requires preventive policies on the sociocultural environment. This work highlights the importance of investing in comprehensive holistic measures from the outset. To tackle the most complex disease we have in the 21st century in the Western world, we logically need a complex approach.

This is a high-quality study that provides very interesting systematic information on a key issue in global public health. The limitations are discussed in the article and in the press release, but they do not appear to have a significant impact on the validity of the results. The results and conclusions are perfectly valid for the context of developed countries and therefore for Spain.

The most important thing is to emphasize the conclusion of the study:

“Our findings indicate that existing early, behavioral, parent-focused interventions alone are insufficient to address childhood obesity.”

The conclusion is that this type of intervention is not sufficient. It is important not to overreach this conclusion and turn it into a decision that, since their effectiveness has not been proven, this type of intervention should be abandoned, as could be inferred from the headline of the press release.

“A meta-analysis of 17 trials including over 9,000 toddlers found no evidence that parent-focused early childhood obesity prevention programs have an impact on young children's BMI.”

On the contrary, as the author herself explains, it is necessary to investigate how to improve them, incorporating new psychosocial intervention methodologies or targeting other age groups and systematizing interventions to facilitate their evaluation. The problem is important enough to continue researching better forms of intervention.

However, the authors raise a second issue that is paramount: the importance of the obesogenic social environment, which makes it difficult for parents to take effective measures and places the burden on them to solve a problem that has a clearly social root:

“Yet, obesity is predominantly driven by upstream environmental and socioeconomic factors that are beyond the capacity of the individual to change.”

These assumptions are considered in the theoretical contributions of Geoffrey Rose, who says that health and disease phenomena are a continuum in the population, and contrasts the strategies commonly used by health services to intervene in sick individuals or those at highest risk with population-based strategies that work with the population as a whole and address the determinants of health problems. In the case of children's nutrition, as the author herself explains, factors such as regulating advertising of unhealthy foods, improving access to healthy foods, availability of spaces for physical activity, etc.

This perspective is perfectly illustrated in Katz's statement, which compares obesity to a flood in which each intervention is a sandbag in a much-needed dike; none of them can stop it, and only when we have done enough things in enough places will they add up to build a dike higher than the water level.

Unfortunately, interventions on structural factors clash with the interests of large corporations in the food industry. In a Lancet article from 2014, McPherson estimated that ‘to prevent health consequences that will be unsustainable, Body Mass Index must return to levels seen 30 years ago in the UK. This would mean an 8% reduction in consumption, costing the food industry £8.7 billion a year’. He therefore wonders whether this will be possible in a neoliberal and competitive world.

Addressing obesity in pre-school children involves many challenges, not least because of parents’ difficulties in recognising and acknowledging their children’s condition [see 2022 study in BCM Public Health]. The review reaches the correct conclusion that more interventions are needed on the food and physical activity environments in which children and young families live, a key condition for enacting change on a large scale. However, behavioural interventions on families at higher risk of early childhood obesity should not be dismissed. They do work when appropriately targeted and designed, usually with the support of primary and community care services. In the context of the STOP (Science and Technology in childhood Obesity) project [Editor's note: coordinated by Sassi from 2018 to 2022], the World Health Organization has provided good practice guidance on how to deploy such interventions.

"The study is of good quality. Clear evidence of this is that it is published in a scientific journal with an impact factor of 18.0, which places it at number 6 out of 419 scientific journals indexed in the field of PUBLIC, ENVIRONMENTAL & OCCUPATIONAL HEALTH. As it is a systematic review with meta-analysis, it includes the best scientific evidence available up to a year ago (September 30, 2024) and data from the 17 studies with the greatest methodological rigor; therefore, the data are more than solid".

How does it fit in with the existing evidence?

"It adds to the evidence obtained for other age groups, which has already pointed out that primary prevention interventions for childhood obesity have difficulty achieving statistically significant improvements in weight status and, above all, clinically relevant improvements. As the article concludes, it is advisable to rethink this type of intervention, and I would add that this rethinking should consider the conceptualization, theoretical foundations, methodologies, and activities as a whole".

Are there any important limitations to consider?

"It does not include quasi-experimental intervention studies, and we agree that it should only include the best available scientific evidence. However, it would be interesting to know what the results would be if these quasi-experimental trials were also included".

Can the conclusions be extrapolated to Spain, even though data from Spain were not analyzed in the study?

"In behavioral sciences based on a social determinants of health approach, it is always advisable to take into account the economic, cultural, and political context in which the study is conducted. However, for this particular meta-analysis and due to the globalization that has taken place worldwide in recent decades, we believe that the results would also be similar in Spain".

Does this mean that family interventions do not work, or that they do not work on their own?

"It means that the scientific evidence to date does not find favorable results for the interventions analyzed, which can be highly questioned in terms of conceptualization, theoretical foundations, and methodology.

On the one hand, family interventions aimed at families with children under 12 months of age should address the root causes and avoid merely recommending specific health habits to be carried out. Such interventions should promote the self-efficacy of the adults in the family unit. This means ensuring that they are deeply convinced that they have the necessary skills to introduce healthy lifestyle habits in their children's development from the earliest stages of life. They should also promote maternal and parental skills around positive parenting that help them to properly introduce complementary feeding, motor development, the incorporation of sleep habits, and the building of a positive emotional bond within the family unit. Finally, it is important to promote their resilience, as this will enable them to adapt in the healthiest way possible to an obesogenic environment that makes it difficult for them to deploy their innate skills in the parenting process. This is how we are evaluating it at the Gasol Foundation through an innovative intervention study focused on early childhood.

On the other hand, through political, legislative, economic, and social measures, it would be advisable to transform the environments and systems in which children currently develop from birth and which clearly influence families who try to develop their skills but encounter many difficulties in doing so effectively.

In short, interventions must be based on an approach that takes into account the social determinants of health, moving away from the mere clinical prescription of behaviors to be carried out, and transforming them into intervention models that facilitate the full deployment of the maternal-parental role of families".

What might the implications be for the design of public policies?

"On the one hand, priority must be given to transforming the social and economic systems in which children currently grow up with their families, and this must be reflected in changes to the environments in which they spend their first months/years of life. Far-reaching policy measures such as the National Strategic Plan for the Reduction of Childhood Obesity (PENROI) should be more common worldwide, and in the case of Spain, efforts should be made to implement the 200 measures it includes by 2030. National, regional, or local plans and strategies specifically aimed at promoting health in a broad and holistic sense in early childhood would also contribute significantly to ensuring that the next meta-analysis on this type of intervention presents more favorable results. It also implies a change of model in the design and evaluation of preventive interventions in public health and, specifically, in community health. We need to move from purely biological approaches with biomedical and clinical approaches to much more social approaches based on the psychosocial determinants of health behaviors that make effective health promotion at the community level possible".

Childhood obesity is a public health priority worldwide. Cardiovascular risk factors, particularly obesity, tend to persist from childhood through adolescence to adulthood. For this reason, numerous interventions have been proposed over the last two decades to prevent obesity from the earliest years of life. While early studies were focused on school age and adolescence, the effectiveness of interventions in the early years of life has subsequently been tested.

This systematic review and meta-analysis pooled data from 17 clinical trials involving children under one year old, to assess whether parent-focused behavioral interventions could reduce adiposity, as measured by BMI z-score — an accepted outcome measure for this type of randomised clinical trials. The included interventions of this meta-analysis were parent-centred and began before birth or in the first year of life. As well as assessing whether they improved BMI z-score at two years of age, the effectiveness of improving other outcomes related to breastfeeding, vegetable intake, sleep, screen time and parental feeding was also evaluated.

Overall, the study found no evidence of the effectiveness of paret-focused interventions on  improving adiposity or other secondary outcomes. Analyses by sex, immigrant status or parental educational level also did not identify a target population that was more responsive to this type of intervention. Likewise, gestational age, maternal BMI, birth weight or income level did not significantly influence the effectiveness of the interventions.

Therefore, if this impeccably designed study shows that parent-focused interventions are ineffective, are these types of intervention a waste of resources? My opinion is that this question cannot be answered using the data from this study for several reasons: the interventions included were very diverse; the groups of children targeted had different levels of risk relating to their family and social contexts; and, in general, the studies were generally very heterogeneous.

As the authors point out, perhaps interventions should focus more on the environmental context in which children live and develop (daycare centres, parental leave, neighborhood greenness, etc.) than on the family environment itself. In any case, the results of this study make it clear that the available scientific evidence is insufficient to recommend parent-delivered interventions for preventing obesity in the first two years of life.