The first 2,000 days hold the key to lifelong health

Targeting the first 2,000 days of life with a comprehensive strategy can significantly reduce childhood obesity and tackle a global problem with integrated, multi-behavioral solutions.

study: Early life factors influencing obesity and the need for complex solutionsImage credit: Lemonsoup14 / Shutterstock

A recent review published in the journal Nature Reviews Endocrinology, The researchers pooled data from more than 175 publications to understand the impact of early childhood factors on the development of obesity later in life.

This review focuses on evidence from biological, sociocultural, environmental, and individual systems levels and highlights the critical role that the first 2,000 days after conception play in altering future obesity risk.

Importantly, this review highlights that these factors interact in complex ways, creating a “web of influences” that differs across socioeconomic and ethnic groups, making it essential to tailor prevention activities to specific populations.

The review findings highlight that inculcating obesity risk-reducing habits in children before obesity risk behaviors are established (during adolescence and adulthood) could significantly mitigate the ongoing global excess weight epidemic.

However, traditional interventions that target behaviors individually have proven ineffective, especially in disadvantaged communities.

Evidence suggests that more comprehensive, multi-layered strategies are needed to address the combined influences of individual, family, societal and environmental factors.

Furthermore, traditional interventions for unhealthy decisions have historically attempted to address individual behaviors, but may not be sufficient as evidence indicates that integrated, multidisciplinary, complex, and multi-behavioral strategies are required to effectively manage unwanted weight gain.

What is obesity and why should you worry?

Obesity is a chronic disease characterized by excess body weight (body mass index ≥ 30 kg/m).²) is caused by abnormal fat accumulation.

Obesity is not only unhealthy in itself, but is also associated with an increased risk of life-threatening complications, including type 2 diabetes (T2D), cardiovascular disease (CVD), reproductive complications, and even some cancers, highlighting the need to effectively prevent or treat obesity.

Alarmingly, despite decades of research into obesity and several nationally promoted public health initiatives, the prevalence of obesity continues to rise.

Global prevalence has more than doubled since 1990, with more than 2.5 billion adults expected to be overweight or obese by 2022.

Notably, obesity is not evenly distributed across the population: children from lower socio-economic backgrounds, Indigenous peoples, and certain minority groups, such as Hispanic and Polynesian communities, are disproportionately affected due to factors such as reduced access to healthy foods, safe places to engage in physical activity, and health care resources.

Why focus on childhood obesity?

Historical observations have noted that obesity risk tends to increase with age: risk during childhood and adolescence was thought to be minimal, but risk increased throughout adulthood until approximately age 75, after which it plateaued or decreased slightly.

Recent studies have highlighted intrauterine and early development as critical periods that profoundly influence the manifestation of chronic diseases in later stages of life.

The Developmental Origins of Health and Disease (DOHaD) theory summarises this hypothesis and highlights that the first 1,000 days after conception are crucial for managing chronic disease risk.

However, the current review expands this focus to the first 2,000 days, highlighting that the complexity of obesity development continues into early childhood as lifestyle habits such as diet and physical activity become established.

Research from the World Health Organization (WHO), UNICEF and the World Bank suggests that surveillance and intervention during the first five years of life is essential. Currently, more than 37 million children under the age of five suffer from childhood obesity.

Given the pathology of the disease, obese children will live with the condition for the rest of their lives. Moreover, habits and behaviors taught in the first few years of life can significantly alter their risk of obesity as adults.

As a result, this review and other recent reviews of obesity suggest expanding the focus of DOHaD to the first 2,000 days after conception (approximately 5 years from conception).

The origins and complexity of childhood obesity

Obesity results from a complex interaction of numerous individual and biological (e.g. genetics), behavioral (e.g. nutrition and sleep habits) and socio-cultural factors.

For infants and newborns, obesity risk may also be modified by factors such as breastfeeding, the mother's health, and maternal behaviors during pregnancy (e.g. smoking).

The socio-ecological model used in this review identifies three main layers of influence: individual and biological factors, socio-cultural factors, and environmental/systemic factors.

Importantly, these layers do not operate independently but form a web of interactions that shape children's risk of obesity. For example, parental and family eating habits interact with broader social influences, such as food marketing and access to exercise spaces, to contribute to the development of obesity.

“Based on the socio-ecological model, factors associated with childhood obesity can be categorized into three groups: individual and biological level, socio-cultural level, and environmental and systems level. It is important to keep in mind that many of these influences affect not only weight status but also the other identified influences, forming a complex web of interactions. Furthermore, the literature is dominated by an examination of the outcomes of obesity defined using BMI, with a paucity of studies assessing body composition.”

So, what can we do?

This review proposes guidelines for obesity prevention across four developmental stages.

During the first stage (in utero, from conception to birth), maternal nutrition, weight gain (including obesity screening), and health behaviors (smoking, alcohol consumption) should be monitored to ensure optimal placental development and minimize the risk of pregnancy-related complications.

The second phase (infancy – up to 12 months of age) is characterized by considerations of nutrition, health behaviors, and motor skill development.

Parents must learn how to recognize and respond to their infant's hunger. Mothers should continue to breastfeed their infants even after they have been given solid foods (after about 6 months of age).

Adequate sleep and daily habits need to be established and taught slowly in infancy (and reaffirmed throughout childhood and adolescence), especially since unhealthy habits are difficult to break once established.

Importantly, the review advocates for “aligned action” – multiple sectors (e.g. health, education, urban planning) working together to create environments conducive to healthy lifestyles. For example, policies that promote green space and walkable neighborhoods can support active play for young children, and food system reforms can improve access to nutritious options.

In stage 3 (toddlers – 1 to 3 years old), parents are encouraged to provide ample opportunities for active play (including outdoor activities) to promote the development of young children's physical strength and motor skills.

Once young children have acquired a basic understanding of food and begin to develop food preferences, they should be involved in meal preparation and planning while teaching them the pros and cons of healthy food choices. In particular, added sugars should be kept to a minimum to prevent obesity and instill a lifelong aversion to excessive sugar intake.

Finally, in the fourth age (preschool children – 3 to 5 years old), children should be encouraged to participate in physical activities that require skills such as sports, dance, etc. Children's eating habits should be monitored, regulated and optimized for the healthy development of the child.

Excessive screen time should be limited while promoting an active lifestyle. BMI and other obesity indicators should be monitored to prevent fat rebound and reduce the risk of obesity. If obesity markers are present, steps should be taken to reverse them before they become fully manifest.

It is important to note that the review calls for customized strategies that take into account the different needs of communities based on their socio-economic and cultural backgrounds.

There is no “one size fits all” solution to childhood obesity, and interventions need to be flexible and adaptive to different contexts.

Conclusion

This review summarizes available data on the prevalence, risk associations, and mitigation measures of childhood obesity, a chronic disease estimated to affect more than 37 million children worldwide.

The review highlights the crucial importance of complex, multi-layered interventions that address not only individual behaviours but also the broader socio-economic and environmental systems that shape them.

Additional research is needed, particularly on risk factors across different ethnicities, before standardized child behavior plans can be developed and publicly promoted.

These solutions require multi-sectoral collaboration, ensuring that health, education and urban planning systems work together to create healthy environments starting from early childhood.

Meanwhile, the review details routine, easy-to-follow guidelines that can be followed throughout the first 5 years of an infant's life to minimize the risk of obesity throughout their life and throughout childhood.