How the first 2,000 days hold the key to lifelong health
Targeting the first 2,000 days of life with comprehensive strategies can significantly reduce childhood obesity, tackling a global issue with integrated, multi-behavioral solutions.
Study: Early life factors that affect obesity and the need for complex solutions. Image Credit: Lemonsoup14 / Shutterstock
In a recent review published in the journal Nature Reviews Endocrinology, researchers collated data from more than 175 publications to elucidate the impacts of early life factors on the subsequent development of obesity.
The review focuses on evidence from biological, sociocultural, environmental, and individual system levels and reveals that the first 2,000 days following conception play a significant role in altering future obesity risk.
Crucially, the review emphasizes that these factors interact in complex ways, creating a ‘web of influences’ that varies across socio-economic and ethnic groups, making it essential to tailor prevention efforts to specific populations.
Review findings highlight that inculcating obesity risk-mitigating habits in children before the establishment of obesity-risk behaviors (during adolescence and adulthood) would substantially alleviate the ongoing global excess weight pandemic.
However, traditional interventions that target behaviors in isolation have proven ineffective, particularly in disadvantaged communities.
Evidence suggests that more comprehensive, multi-layered strategies are necessary to address the combined effects of individual, familial, societal, and environmental factors.
Furthermore, conventional interventions against poor health decisions, which historically attempt to address behaviors individually, may not suffice as evidence suggests integrated, multidisciplinary, and complex multi-behavior strategies are required to manage unwanted weight gain effectively.
What is obesity, and why should we be concerned?
Obesity is a chronic condition characterized by excess body weight (body mass index ≥ 30 kg/m2) due to abnormal fat retention.
While independently unhealthy, obesity is associated with the increased risk of several life-threatening comorbidities, including type 2 diabetes (T2D), cardiovascular diseases (CVDs), reproductive complications, and even several cancers, highlighting the need to prevent or treat the condition effectively.
Alarmingly, despite decades of research and several nationally promoted public health initiatives against obesity, the prevalence of the disease continues to rise.
Global prevalence rates have more than doubled since 1990, with more than 2.5 billion adults overweight or obese as of 2022.
Notably, obesity is not evenly distributed across populations. Children from lower socio-economic backgrounds, Indigenous groups, and certain ethnic minorities—such as Hispanic and Polynesian communities—are disproportionately affected, often due to factors like reduced access to healthy food, safe spaces for physical activity, and healthcare resources.
Why should we focus on childhood obesity?
Historical observations noted an age-associated trend in obesity risk. Children and adolescents were thought to be at minimal risk, which increased through adulthood till ~75 years and then plateaued or slightly decreased.
More recent research has highlighted the importance of utero and early growth as critical periods that profoundly affect the manifestations of chronic diseases in later life stages.
The developmental origins of health and disease (DOHaD) theory encapsulates this hypothesis and emphasizes the importance of the first 1,000 days following conception as imperative in managing chronic disease risk.
However, the current review expands this focus to the first 2,000 days, highlighting that the complexity of obesity development extends through early childhood as lifestyle habits such as diet and physical activity become entrenched.
Research by the World Health Organization (WHO), United Nations Children’s Fund (UNICEF), and the World Bank suggests that monitoring and intervening in the first five years of life are imperative – more than 37 million children <5 years currently suffer from childhood obesity.
Given the pathology of the disease, children with obesity will live with the condition for the rest of their lives. Furthermore, habits and behaviors taught during the first few years of life can significantly alter adult obesity risk.
Consequently, the present- and other recent obesity reviews suggest that the DOHaD focus be extended to the first 2,000 days following conception (conception to ~5 years).
The genesis and complexity of early life obesity
Obesity arises from the complex interplay between numerous individual and biological influences (e.g., genetics), behaviors (e.g., nutrition and sleep habits), and sociocultural factors.
In infants and neonates, obesity risk may also be altered by factors such as breastfeeding, maternal health, and maternal behaviors during pregnancy (e.g., smoking).
The socioecological model used in the review identifies three main layers of influence—individual and biological, sociocultural, and environmental/systemic factors.
Importantly, these layers do not operate independently; rather, they create a web of interactions that shape a child’s obesity risk. For example, parental feeding practices and family dietary habits interact with broader societal influences, such as food marketing and access to physical activity spaces, contributing to the development of obesity.
“Based on the socioecological model, factors associated with early life obesity can be put into three groups: individual and biological; sociocultural; and environmental and system levels. It is important to note that many of these influences affect not only weight status but also other identified influences, creating a complex web of interactions. In addition, there is a preponderance of literature focused on examining obesity outcomes defined using BMI, and a scarcity of studies assessing body composition.”
So, what can we do about it?
The present review suggests guidelines for obesity prevention across four developmental stages.
During the first stage (in utero – conception to birth), maternal nutrition, weight gain (including obesity screening), and health behaviors (smoking, drinking) must be monitored to ensure optimal placental development and minimize the risk of pregnancy-associated complications.
The second stage (infancy – birth to 12 months) is characterized by nutritional, health behavior, and motor skill development considerations.
Parents must be educated on identifying and addressing hunger in their infants. Mothers should breastfeed their infants even after introducing solid foods (~6 months following birth).
Adequate sleep and daily routines should slowly be established and taught in infants (and reaffirmed as they pass through childhood and adolescence), especially since poor health habits, once adopted, are tough to give up.
Crucially, the review advocates for “joined-up action,” where multiple sectors (e.g., healthcare, education, urban planning) collaborate to create environments conducive to healthy lifestyles. For instance, policies promoting green spaces and walkable neighborhoods can support active play for toddlers, while food system reforms can ensure better access to nutritious options.
During the third (toddler – one to three years) stage, parents are encouraged to provide ample opportunity for active play (including outdoor activities), enhancing their toddlers’ fitness and motor skill development.
Once toddlers have achieved a baseline understanding of food and have begun developing food preferences, they should be included in meal preparation and planning while being taught the pros and cons of healthy dietary choices. Notably, added sugars should be minimized both to prevent obesity and to instill a lifelong aversion to excessive sugar intake.
Finally, during the fourth (preschooler – three to five years), children should be encouraged to partake in skill-associated physical activities, including sports and dance. Their eating habits should be monitored, regularized, and optimized for healthy childhood development.
Active lifestyles must be promoted, while excessive screen time must be restricted. BMI and other obesity metrics must be monitored to prevent adiposity rebound and reduce obesity risk. If present, steps to reverse obesity markers must be implemented before it manifests fully.
It is important to note that the review calls for tailored strategies that account for the differing needs of communities based on their socio-economic and cultural contexts.
There is no ‘one-size-fits-all’ solution to childhood obesity, and interventions must be flexible and adaptive to these varying contexts.
Conclusions
The present review collates available data on the prevalence, risk associations, and mitigation measures against childhood obesity, a chronic condition estimated to affect more than 37 million children worldwide.
The review highlights the critical need for complex, multi-level interventions that address not only individual behaviors but also the broader socio-economic and environmental systems that shape them.
Additional research into risk factors, particularly across various ethnicities, is required before a standardized childhood action plan can be developed and publically promoted.
Such solutions must involve multi-sector collaboration, ensuring that healthcare, education, and urban planning systems work together to create environments conducive to health from early childhood onwards.
In the interim, the review details routine and straightforward guidelines that can be followed across the first five years of infants’ lives to minimize their obesity risk, both during childhood and throughout their lifetimes.
