Researchers studied what happens when nursing mothers eat very little food during the breastfeeding period. Using rat mothers and their babies, they found that when mothers severely restricted their food intake—either eating only half their normal amount or fasting every other day—their babies didn’t grow properly and developed problems with blood sugar control and brain chemistry. These effects lasted even after the babies stopped nursing and grew into teenagers. The study suggests that mothers need adequate nutrition while breastfeeding to help their babies develop healthy brains and metabolisms.

The Quick Take

  • What they studied: Whether eating very little food while nursing affects a mother’s health and her babies’ development, growth, and brain function
  • Who participated: Wistar rat mothers (a common research breed) and their litters of eight pups each. Three groups were compared: mothers eating normally, mothers eating 50% of normal food, and mothers fasting every other day throughout the entire nursing period
  • Key finding: Babies born to mothers who severely restricted food showed poor growth, low blood sugar levels, and changes in brain chemistry that lasted into their teenage years. Both male and female babies were affected equally
  • What it means for you: This research suggests nursing mothers should maintain adequate nutrition for their babies’ healthy development. While this study used rats, it highlights why doctors recommend mothers eat enough during breastfeeding. Always consult your healthcare provider about nutrition during nursing

The Research Details

Researchers divided nursing rat mothers into three groups: one group ate normal amounts of food, one group ate only half the normal amount, and one group alternated between eating normally one day and fasting the next day. This pattern continued throughout the entire nursing period. The researchers measured how much the mothers and babies weighed, how much they ate and drank, and tested their blood for important nutrients and chemicals. They also examined the babies’ brains after they grew into teenagers to see if the early nutrition affected brain chemistry.

This type of study is called an animal model study. Scientists use animals like rats to understand how nutrition affects development because rats have similar biological systems to humans, but researchers can control conditions more carefully than they could with human families. The study tracked both male and female babies to see if nutrition affected them differently.

The nursing period is when babies receive all their nutrition from their mother’s milk, making maternal diet critically important. By studying this carefully controlled situation, researchers can understand cause-and-effect relationships that would be impossible to study in humans. The findings help explain why proper nutrition during nursing matters for long-term health

This is a controlled laboratory study with clear comparison groups, which is a strong research design. The researchers measured multiple important health markers including weight, blood chemistry, and brain function. However, because this used rats rather than humans, results may not apply exactly the same way to people. The study was published in a peer-reviewed scientific journal, meaning other experts reviewed it before publication

What the Results Show

Mothers who severely restricted food lost significant weight during nursing, which was expected. More importantly, their babies showed serious problems: both male and female offspring weighed less and remained smaller even after weaning and into their teenage years.

The babies’ blood sugar levels were abnormally low, a condition that can affect energy and brain function. When researchers examined the babies’ brains, they found reduced activity of an important protective chemical called superoxide dismutase (SOD), which normally helps protect brain cells from damage.

These problems weren’t temporary—they persisted long after the babies stopped nursing and grew into adolescence. This suggests that poor nutrition during the nursing period created lasting changes in how the babies’ bodies and brains worked.

The study also measured other blood chemicals including cholesterol, triglycerides, and liver function markers. While the abstract doesn’t detail all these results, the focus on glucose and brain chemistry suggests these were the most significant findings. The fact that both male and female babies showed similar problems indicates that maternal nutrition affects all babies regardless of sex

Previous research has shown that maternal nutrition during pregnancy and nursing affects baby development, but this study specifically examined how severe food restriction during nursing—rather than pregnancy—impacts long-term outcomes. The findings align with existing knowledge that the nursing period is critical for brain development and metabolism, and extend our understanding by showing how lasting these effects can be

This study used rats, not humans, so results may not translate exactly to people. The sample size was relatively small (16 litters total). The study doesn’t tell us whether these effects could be reversed with better nutrition later in life, or how severe the restriction needs to be to cause problems. Real-world maternal nutrition is more complex than the controlled conditions in this study

The Bottom Line

Nursing mothers should maintain adequate calorie and nutrient intake to support both their own health and their babies’ development. This research supports current medical guidance that mothers shouldn’t severely restrict calories while breastfeeding. If a mother needs to lose weight or manage her diet, she should work with a healthcare provider to do so safely. Confidence level: High—this aligns with established medical recommendations

Nursing mothers and those planning to breastfeed should pay attention to this research. Healthcare providers, lactation consultants, and prenatal educators can use this information when counseling mothers about nutrition. This is less relevant for mothers using formula, though good nutrition remains important for all mothers’ health

The effects observed in this study appeared during nursing and persisted into adolescence (months later in rats). In humans, impacts on growth and metabolism might become noticeable within weeks to months of inadequate maternal nutrition, though some effects on brain development might not be apparent until later childhood

Want to Apply This Research?

  • Nursing mothers could track daily calorie intake and compare it to recommended amounts (typically 300-500 extra calories per day while breastfeeding). The app could send reminders to log meals and provide feedback on whether intake meets nursing nutrition guidelines
  • Users could set a goal to eat three balanced meals plus two healthy snacks daily while nursing, logging each one in the app. The app could suggest nutrient-dense foods important for milk production and track whether daily intake meets calorie and protein targets
  • Track weekly weight changes (expecting gradual, healthy loss of pregnancy weight), energy levels, and milk supply as indicators of adequate nutrition. Monitor baby’s growth at regular pediatric checkups as the ultimate indicator of nursing nutrition adequacy

This research was conducted in rats and may not apply exactly the same way to humans. Nursing mothers should not restrict calories or fast without consulting their healthcare provider, as adequate nutrition is essential for milk production and baby development. If you’re nursing and considering any dietary changes, including weight loss, speak with your doctor or a registered dietitian who specializes in lactation. This information is for educational purposes and should not replace professional medical advice