Researchers studied what 1,383 preschool children in southern China ate and how it connected to their growth and blood nutrient levels. They found that most children had good or decent diets, but the foods that help prevent being too thin are different from the foods that prevent being overweight. Interestingly, heavier children ate more food overall and had more variety in their diets, but took fewer vitamins. The study shows that one-size-fits-all nutrition advice doesn’t work—children who are too thin need different dietary help than children who are overweight.

The Quick Take

  • What they studied: How the foods preschool children eat in southern China relate to their weight, growth, and the nutrients in their blood
  • Who participated: 1,383 preschool-aged children (typically ages 3-5) treated at Foshan Women and Children Hospital between January 2023 and December 2024
  • Key finding: About 8.7% of children were underweight, 3.6% were overweight, and 3.4% were obese. Most children (84.6%) had good or medium-quality diets, but the diet factors that protect against being too thin are different from those that protect against being overweight
  • What it means for you: If you’re a parent of a preschooler in China, nutrition advice should be tailored to your child’s specific weight situation rather than following generic guidelines. Talk to your pediatrician about your child’s individual needs

The Research Details

This was a cross-sectional study, which means researchers collected information from children at one point in time (between 2023-2024) rather than following them over months or years. They gathered three types of information: what the children ate (dietary intake), their body measurements like height and weight (anthropometric data), and blood tests showing nutrient levels (serum nutrients like iron and hemoglobin). The researchers then looked for patterns—did children who ate certain foods have different weights or blood nutrient levels?

The study took place at a hospital in Foshan, a city in southern China, so the findings apply specifically to that region. Researchers recorded detailed information about each child’s diet, measured their physical growth, and took blood samples to check their iron, hemoglobin (the protein that carries oxygen in blood), and ferritin (a protein that stores iron) levels.

This research approach is important because it captures real-world eating patterns of actual children rather than testing them in a lab. By looking at many children at once, researchers could spot patterns about which foods and eating habits connect to healthy growth and good blood nutrient levels. This helps doctors and parents understand what works best for children in this region

The study included a large number of children (1,383), which makes the findings more reliable. However, because it’s a cross-sectional study, it shows relationships between diet and health but cannot prove that diet directly causes weight changes—other factors could be involved. The study was conducted at a hospital, so it may not represent all children in the region, as healthier children might not visit the hospital as often

What the Results Show

The researchers found that most preschoolers in southern China have good nutrition overall: 38.5% had ideal diet quality and 46.1% had intermediate (medium) diet quality. Only about 15% had low-quality diets. Weight distribution showed that most children were at healthy weights, with 8.7% underweight, 3.6% overweight, and 3.4% obese.

A surprising finding was that overweight and obese children actually ate more food overall and had greater variety in their diets compared to underweight children. However, these heavier children took fewer dietary supplements (like vitamins). This suggests that the problem isn’t necessarily eating too much, but rather the types of foods being eaten and how balanced the diet is.

The most important discovery was that diet quality affects underweight and overweight children differently. Low diet quality was a risk factor for being underweight, meaning children eating lower-quality diets were more likely to be too thin. However, intermediate and low diet quality appeared to protect against being overweight—children with lower-quality diets were less likely to be overweight. This counterintuitive finding suggests that the nutritional needs and dietary factors are different for children at different weight levels.

Blood nutrient levels showed clear patterns. As children’s body weight increased, their hemoglobin levels (the protein that carries oxygen) also tended to increase. Children with higher overall diet quality had better levels of hemoglobin, serum iron, and ferritin—all important for preventing anemia and supporting healthy development. This suggests that diet quality directly impacts the body’s ability to absorb and use iron effectively

This study aligns with previous research showing that diet quality matters for child development, but it adds important nuance by showing that the relationship between diet and weight is more complex than previously thought. Most prior studies suggested that low-quality diets lead to obesity, but this research found that in this population, low-quality diets were actually associated with being underweight. This may reflect regional differences in food availability, cultural eating patterns, or economic factors in southern China

The study was conducted at a single hospital, so the results may not represent all children in southern China. Children visiting hospitals may be healthier or sicker than the general population, which could skew results. Because this is a cross-sectional study (snapshot in time), we cannot determine whether diet causes weight changes or if weight changes cause different eating patterns. The study doesn’t explain why overweight children ate more but took fewer supplements, so we can’t be certain about the reasons behind these patterns. Additionally, dietary information was collected at one point and may not reflect typical eating patterns over time

The Bottom Line

Based on this research (moderate confidence): Parents should focus on diet quality rather than just portion size. For underweight children, improving diet quality appears important. For overweight children, the focus should be on the types of foods rather than simply eating less. All children should receive adequate iron-rich foods or supplements to support healthy blood nutrient levels. These recommendations should be personalized with guidance from your pediatrician based on your child’s individual situation

This research is most relevant to parents of preschool-aged children (ages 3-5) in southern China or similar regions with comparable food availability and cultural eating patterns. Healthcare providers, nutritionists, and public health officials in China should pay attention to these findings. Parents in other regions may find some insights useful, but should recognize that food availability and cultural practices differ. This research is less directly applicable to preschoolers in other countries with different food systems

Changes in diet quality may show effects on blood nutrient levels within weeks to a few months, as the body responds relatively quickly to improved nutrition. However, changes in weight and growth patterns typically take several months to become noticeable. Parents should expect to see improvements in energy levels and overall health before significant weight changes occur

Want to Apply This Research?

  • Track your preschooler’s daily food intake by food groups (grains, proteins, fruits, vegetables, dairy) and rate overall diet quality on a simple scale. Also note any supplements given. Monitor this weekly to identify patterns in diet quality and correlate with your child’s energy levels and growth measurements from doctor visits
  • If your child is underweight, use the app to ensure they’re eating from all food groups daily and gradually increase nutrient-dense foods. If your child is overweight, focus on improving food variety and quality rather than reducing portions—track the types of foods eaten to ensure balance. For all children, set a goal to include iron-rich foods (meat, beans, fortified cereals) at least 5 days per week
  • Monthly, review your child’s diet quality score and compare it to their growth measurements from pediatric visits. Track any changes in energy, appetite, or growth over 3-month periods. If using supplements, log them in the app to ensure consistency. Share these records with your pediatrician at regular check-ups to adjust nutritional strategies as needed

This research describes patterns in one population of preschool children in southern China and should not be used as a substitute for personalized medical advice. Every child has unique nutritional needs based on their age, health status, activity level, and individual circumstances. Before making significant changes to your child’s diet or starting supplements, consult with your pediatrician or a registered dietitian. This study shows associations between diet and health outcomes but does not prove cause-and-effect relationships. If you have concerns about your child’s growth, weight, or nutrition, seek professional medical evaluation rather than relying solely on this research