Modifiable risk factors related to obesity in childhood | Knowledge for policy

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Modifiable risk factors related to obesity in childhood as described by health-related organisations

Effect of diet on obesity in childhood
WHO 2018
‘Excess calories from foods and drinks high in free sugars also contribute to unhealthy weight gain, which can lead to overweight and obesity’.
EFSA 2022
'[P]ositive and causal relationship between the intake of [sugar-sweetened beverages] ad libitum and risk of obesity' (>75-100% probability). '[P]ositive and causal relationship between the intake of [fruit juices] and risk of obesity (0-15% probability).
DGE 2012
‘The available studies regarding children and adolescents mainly suggest that carbohydrate intake or dietary carbohydrate proportion, respectively, is not associated with the risk of obesity. The respective evidence is judged as probable.’ ‘The evidence regarding an increased risk of obesity due to higher consumption of sugar-sweetened beverages in children and adolescents is […] judged as possible. The evidence regarding an increased risk of obesity especially in children and adolescents with initially already increased BMI or already existing overweight is also judged as possible.’ ‘[P]ossible evidence that there is no association between dietary fibre intake and the risk of obesity’ in children and adolescents.
NNR 2023 (pdf)
‘[P]robable evidence for a causal relationship between total and animal protein intake and higher BMI in children up to 18 years of age’. Sugar-sweetened beverage ‘consumption is associated with obesity’ ‘there is strong evidence for an association between ultra-processed foods as a group and weight gain and obesity.’
DGAC 2025
‘Dietary patterns consumed by children and adolescents that are characterized by higher intakes of vegetables, fruit, legumes, nuts, whole grains, fish/seafood, and dairy (low-fat, unsweetened) and lower intakes of red and processed meats, sugar-sweetened beverages, and sugar-sweetened or savory/salty snack foods are associated with favorable growth patterns, lower adiposity, and lower risk of obesity later in childhood and early adulthood. This conclusion statement is based on evidence graded as limited. (Grade: Limited).' ‘Dietary patterns consumed by children and adolescents that are characterized by higher intakes of red and processed meats, refined grains, sugar-sweetened beverages, sugar-sweetened or savory/salty snack foods, and fried potatoes and lower intakes of vegetables, fruit, and whole grains are associated with unfavorable growth patterns, higher adiposity, and higher risk of obesity later in childhood and early adulthood. This conclusion statement is based on evidence graded as limited. (Grade: Limited).’ 'Dietary patterns consumed by children and adolescents with higher amounts of food classified as ultra- processed food are associated with greater adiposity (fat mass, waist circumference, BMI) and greater risk of overweight. This conclusion statement is based on evidence graded as limited. (Grade: Limited).' 'Total milk consumption by younger children may be associated with favorable growth and body composition, and lower risk of obesity during childhood. This conclusion statement is based on evidence graded as limited. (Grade: Limited).' 'Consumption of higher-fat dairy milk compared to lower-fat dairy milk by younger children may be associated with favorable growth and body composition, and lower risk of obesity during childhood. This conclusion statement is based on evidence graded as limited. (Grade: Limited).' 'There may not be a relationship between consumption of sweetened milk by older children and adolescents and growth, body composition, and risk of obesity. This conclusion statement is based on evidence graded as limited. (Grade: Limited).' '100% juice consumption by children and adolescents is not associated with growth, body composition, and risk of obesity. This conclusion statement is based on evidence graded as moderate. (Grade: Moderate).' 'Sugar-sweetened beverage consumption by infants, children, and adolescents is associated with unfavorable growth patterns and body composition, and higher risk of obesity in childhood up to early adulthood. This conclusion statement is based on evidence graded as moderate. (Grade: Moderate).' 'Low- and no-calorie sweetened beverage consumption by children and adolescents may not be associated with growth, body composition, and risk of obesity. This conclusion statement is based on evidence graded as limited. (Grade: Limited).' 'Regular breakfast consumption by children and adolescents may be associated with favorable outcomes related to growth, body composition, and/or lower risk of obesity. This conclusion statement is based on evidence graded as moderate. (Grade: Moderate).' 'Frequency of daily snacking during childhood may not be associated with outcomes related to growth, body composition, and/or risk of obesity. This conclusion statement is based on evidence graded as limited. (Grade: Limited).' 'Higher number of eating occasions per day during childhood may be associated with favorable outcomes related to growth, body composition, and/or lower risk of obesity. This conclusion statement is based on evidence graded as limited. (Grade: Limited).' 'Meal frequency/skipping by children and adolescents may not be associated with outcomes related to risk of overweight or obesity. This conclusion statement is based on evidence graded as limited. (Grade: Limited).'

Effect of physical (in)activity and sedentary behaviour on obesity in childhood
WHO 2024
In children and adolescents '[r]egular physical activity is associated with ...reduced body fat.’ In children and adolescents, 'higher amounts of sedentary behaviour are associated with … increased adiposity...’
WHO 2019b
For infants … ‘[t]he benefit of at least 5 hours of unrestricted movement per day is reduced adiposity.’ For children 1-4 years of age … ‘[m]ost studies showed a favourable or inconclusive association [of physical activity] with adiposity, and very few studies showed an unfavourable association' The evidence for physical activity and adiposity was rated low quality. 'The benefits of less screen-based sedentary behaviour (TV viewing, watching videos, playing computer games) include reduced adiposity.’ 'The benefits of less time spent restrained (car seats, prams/strollers, high chairs, or strapped on a caregiver’s back) include reduced adiposity.’ There was moderate to very low-quality evidence for screen time and adiposity, and very low-quality evidence for overall sedentary time and adiposity. 'Combinations of longer sleep duration and less sedentary screen time, and longer sleep duration and more physical activity were favourably associated with … adiposity.' The evidence for adiposity and the combinations of physical activity, sedentary time and sleep was low quality. ‘Documented health benefits of regular physical activity among young people … include reduced body fat.’
WHO 2014 (pdf)
‘Documented health benefits of regular physical activity among young people … include reduced body fat.’
Physical Activity Guidelines for Americans 2018 (pdf) .
‘Regular physical activity … helps control body weight or reduce body fat in children and adolescents ages 3 through 17 years. Throughout childhood and adolescence, higher levels of physical activity are associated with smaller increases in body weight and adiposity.’

Effect of sleep on obesity in childhood
WHO 2019b
‘Shorter sleep duration is unfavourably associated with adiposity’. The evidence for sleep and adiposity was rated low quality. ‘Combinations of longer sleep duration and less sedentary screen time, and longer sleep duration and more physical activity were favourably associated with … adiposity.’ The evidence for adiposity and the combinations of physical activity, sedentary time and sleep was low quality.
National Sleep Foundation 2015
‘Limited evidence suggests an association between short sleep duration and abnormal physical growth and obesity’ in infants 4-11 months old. Recommended sleep duration for infants is 12-15 hours. ‘Experiential studies reveal an association between short sleep duration [and] obesity...’ in toddlers 1-2 years old. Recommended sleep duration for toddlers is 11-14 hours. ‘Evidence showing that preschoolers [3-5 years old] who slept less than 9 hours per night have greater odds of being obese than those sleeping 10 or more’. Recommended sleep duration for preschoolers is 10-13 hours. ‘short sleep duration in teenagers [14-17 years old] potentially leading to … obesity’. Recommended sleep duration for teenagers is 8-10 hours.

Effect of pollutants and chemicals on obesity in childhood
WHO 2012
‘Limited epidemiological data exist to support the notion that [endocrine disrupting chemicals] exposure during pregnancy can affect weight gain in infants and children.'
EEA 2022
‘[L]imited evidence for an association of air pollution with increased weight or risk of obesity in the young, especially for No2 and PM… the evidence base can be considered as low.’

Effect of perinatal period on obesity in childhood
WHO 2017
‘Excessive weight gain during pregnancy … [has] been found to contribute to overweight in children.’
WHO 2016 (pdf)
‘Children who have suffered from undernutrition and were born with low birth weight or are short-for-age (stunted), are at far greater risk of developing overweight and obesity when faced with energy-dense diets and a sedentary lifestyle later in life.’ ‘mother entering pregnancy with obesity […] predisposes the child to increased fat deposits associated with metabolic disease and obesity.’
WHO 2021b
Gestational 'tobacco smoke exposure is associated with becoming overweight or obese during childhood’.

Effect of breastfeeding and complementary feeding on obesity in childhood
NNR 2023 (pdf)
Strong evidence that breastfeeding is linked with 'lower risk of overweight and obesity for the child'.
WHO 2023c
Children and adolescents who were breastfed as babies are less likely to develop overweight or obesity.
DGAC 2025
‘Introducing grains at or before age 4 months is associated with higher BMI z-score during childhood. This conclusion statement is based on evidence graded as limited. (Grade: Limited)’
DGAC 2020
‘Moderate evidence from observational studies indicates that ever, compared with never, consuming human milk is associated with lower risk of overweight and obesity at ages 2 years and older, particularly if the duration of human milk consumption is 6 months or longer.’ ‘Moderate evidence suggests that first introduction of any complementary food or beverage between the ages of 4 and 5 months compared to approximately 6 months of age is not associated with weight status, body composition, body circumferences, weight, or length among generally healthy, full-term infants.’ ‘Limited evidence suggests that introducing complementary foods or beverages before age 4 months of age may be associated with higher odds of overweight or obesity’. ‘Limited evidence suggests that sugar-sweetened beverage consumption during the complementary feeding period is associated with increased risk of obesity in childhood, but is not associated with other measures of growth, size, and body composition.’
WHO 2016 (pdf)
‘The first years of life are critical in establishing good nutrition and physical activity behaviours that reduce the risk of developing obesity. Exclusive breastfeeding for the first six months of life, followed by the introduction of appropriate complementary foods, is core to optimizing infant development, growth and nutrition’.
UNICEF 2020 (pdf)
Optimal breastfeeding practices, including six months of exclusive breastfeeding and continued breastfeeding for up to two years, protects against overweight and obesity.’ ‘[C]hildren who are fed unhealthy complementary foods are at increased risk of overweight and obesity'.

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