Low Energy Availability with and without a High-Protein Diet Suppresses Bone Formation and Increases Bone Resorption in Men: A Randomized Controlled Pilot Study

Nutrients. 2021 Feb 28;13(3):802. doi: 10.3390/nu13030802.


Suppression of insulin-like growth factor 1 (IGF-1) and leptin secondary to low energy availability (LEA) may contribute to adverse effects on bone health. Whether a high-protein diet attenuates these effects has not been tested. Seven men completed three five-day conditions operationally defined as LEA (15 kcal kg fat-free mass (FFM)-1 day-1) with low protein (LEA-LP; 0.8 g protein·kg body weight (BW)-1), LEA with high protein (LEA-HP; 1.7 g protein·kg BW-1) and control (CON; 40 kcal·kg FFM-1·day-1, 1.7 g protein·kg BW-1). In all conditions, participants expended 15 kcal·kg FFM-1·day-1 during supervised cycling sessions. Serum samples were analyzed for markers of bone turnover, IGF-1 and leptin. The decrease in leptin during LEA-LP (-65.6 ± 4.3%) and LEA-HP (-54.3 ± 16.7%) was greater than during CON (-25.4 ± 11.4%; p = 0.02). Decreases in P1NP (p = 0.04) and increases in CTX-I (p = 0.04) were greater in LEA than in CON, suggesting that LEA shifted bone turnover in favour of bone resorption. No differences were found between LEA-LP and LEA-HP. Thus, five days of LEA disrupted bone turnover, but these changes were not attenuated by a high-protein diet.

Keywords: aerobic exercise; caloric restriction; energy deficit.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Biomarkers / blood
  • Body Composition
  • Bone Remodeling / physiology
  • Bone Resorption / blood
  • Bone Resorption / etiology*
  • Bone Resorption / physiopathology
  • Diet, High-Protein*
  • Dietary Proteins / administration & dosage*
  • Energy Intake / physiology*
  • Energy Metabolism / physiology
  • Exercise / physiology
  • Humans
  • Insulin-Like Growth Factor I / analysis
  • Leptin / blood
  • Male
  • Osteogenesis / physiology*
  • Pilot Projects*
  • Single-Blind Method


  • Biomarkers
  • Dietary Proteins
  • Leptin
  • Insulin-Like Growth Factor I