High-Protein Diets Alters Body Composition and Improves Insulin Resistance in a Rat Model of Low Birth Weight

Abstract

Objective

We aimed to investigate the effects of early high-protein supplementation on low birth weight (LBW)–associated adult metabolic disturbances.

Materials and Methods

This study involved 32 LBW rat pups that were fed a normal protein (20% of energy intake) diet or high-protein (30% of energy intake) diet on their first 4 weeks of life. Sixteen rat pups with normal birth weight (NBW) fed the normal-protein diet were included as control. Biochemical measurements were performed at 4 and 12 weeks of age.

Results

Low birth weight offspring showed significantly (P < 0.05) increased fat mass percentage and adipocyte size and decreased lean mass percentage and muscle fiber size relative to NBW offspring. These LBW-related changes in body composition were corrected by high-protein diet intervention. At 12 weeks of age, the fasting insulin level (7.14 ± 0.83 vs 9.27 ± 0.67 mU/L) and homeostasis model of insulin resistance (1.71 ± 0.35 vs 2.30 ± 0.44) were significantly lower in high protein–fed LBW offspring than in normal protein–fed LBW offspring. Low birth weight rat pups showed a significant (P < 0.05) reduction in serum adiponectin concentrations, glucose transporter 4 mRNA abundance, and phosphorylation levels of AMP-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR) relative to NBW controls. These LBW-associated alterations in gene expression were reversed by early high-protein treatment.

Conclusions

Early postnatal high-protein intake alters the body composition and improves insulin resistance in adults with LBW, which is associated with activation of the AMPK and mTOR pathways.