A new study suggests that a child’s biological sex may influence how early sugar consumption affects body fat development. The research, posted on the medRxiv preprint server, analyzed whether sex altered the connection between sugar exposure during the first 1,000 days—from conception to roughly 24 months—and body composition. Investigators reviewed dietary and body-fat data from 130 mother-child pairs participating in two NIH-funded studies.
The team, from the University of Kansas Medical Center, examined intake during pregnancy and early childhood. They used 24-hour dietary recalls at specific intervals, including two weeks, six months, and 24 months. This period represents a critical window of developmental plasticity where early environmental exposures can influence later metabolic health. For the full cohort, researchers measured waist circumference and skinfold thickness at approximately 24 months to assess adiposity. The study population included 65 boys and 65 girls, with 66.9% recorded as White.
This distinction matters because parents often focus on total calories or general guidelines without considering biological differences.
The results revealed different patterns depending on timing and sex. In the subset of children with dual-energy X-ray absorptiometry scans, maternal prenatal added sugar intake showed a stronger positive association with percentage body fat in girls. The researchers noted that this prenatal link correlated more heavily with central and peripheral fat mass in daughters than in sons. Additionally, prenatal fructose was more strongly associated with waist circumference in boys, though this link was not statistically significant in the full cohort.
However, the relationship shifted during infancy. Higher added sugar intake during this period linked more strongly to adiposity in boys. The analysis showed that boys experienced a stronger connection between early added sugars and fat mass in central and peripheral regions during their first year compared to girls. Fructose intake during infancy, however, showed a stronger positive association with fat-free mass in girls than boys.
Researchers from the University of Kansas Medical Center’s Departments of Dietetics and Nutrition and of Biostatistics and Data Science carried out the investigation. The analysis used mother-child dyads that had been enrolled in two NIH-funded studies. Children were examined at a mean age of 24.6 months and the cohort comprised 65 males and 65 females; 66.9 % were identified as White and 61.5 % as non-Hispanic.
Maternal diet was assessed between 12 and 20 weeks of pregnancy. Offspring diet was measured at two weeks, six months, 12 months, and 24 months using a single 24-hour dietary recall at each assessment. Postnatal intakes were averaged to represent Year 1 and Year 2, and at ~24 months, staff assessed child waist circumference and skinfold thickness. Sugar intake was expressed as a percentage of total energy.
Research Methodology and Limitations
Dual-energy X-ray absorptiometry (DXA) attempts were made on the participants, yet only 42 youngsters possessed both complete dietary records and usable scans. These scans provided data on percent body fat, total fat mass, fat-free mass, as well as central and peripheral adipose tissue. The investigators applied multivariable linear regression models to test whether the relationships differed between boys and girls.
The findings indicated sex-specific patterns that varied with the timing of sugar exposure. In the toddler phase, fructose intake showed a non-significant tendency toward a stronger positive link with central skinfold thickness in boys compared with girls. Across all exposure windows, there were no significant differences in sugar consumption between male and female offspring.
The present study suggests that associations between early dietary sugar intake and body composition at 24 months may vary with developmental timing and child sex. The findings do not establish that sugars cause changes in body fat, and suggested explanations involving placental biology and infant growth remain untested. The work has been released as a preprint and has not undergone peer review, with a DOI of 10.64898/2026.10.16.26365755.
