Suboptimal refeeding compensates stunting in a mouse model of juvenile malnutrition

Background Early life, particularly after weaning, is the most rapid period of growth in mammals, and this growth is highly dependent on adequate nutrition. Protein-energy malnutrition (PEM) during this critical window can lead to stunting and wasting, which have long-term health consequences. Objective This study aimed to develop a mouse model of juvenile PEM to assess the effects of refeeding with various diets and interventions on growth recovery, including the impact of probiotic supplementation and suboptimal refeeding diets. Methods Juvenile C57Bl/6J mice were fed a low-protein diet (LPD, 5% kcal from protein) starting at postnatal day 14 (P14) to induce malnutrition. Following weaning, both male and female mice were refed an optimal diet (Altromin 1310, 27% kcal from protein) at different times ranging from P28 to P56. In a second intervention, male mice were supplemented during refeeding with Lactiplantibacillus plantarum WJL (Lp WJL ), a probiotic known to stimulate growth in malnourished conditions. A final group of malnourished male mice were refed with a Western diet (WD, 34.5% kcal from fat; 15.3% kcal from protein) or a modified Western diet (MWD, 34.2% kcal from fat; 7.5% kcal from protein) to model suboptimal refeeding. Results Refeeding with an optimal diet fully restored growth in female mice, but male mice exhibited persistent stunting despite nutritional rehabilitation. Lp WJL treatment during refeeding did not enhance systemic growth in males. In contrast, refeeding with WD or MWD restored body length but impaired glucose metabolism, particularly in mice refed MWD after PEM. Lp WJL exacerbated glucose intolerance in the suboptimal refeeding groups. Conclusion Sex-dependent differences exist in the recovery from early-life malnutrition, with males showing incomplete growth recovery despite optimal refeeding. Suboptimal diets, while compensating for stunting, impair glucose metabolism, especially when protein intake is insufficient. Probiotic supplementation with Lp WJL did not improve growth outcomes.