The aim of this study is to investigate potential metabolic effects of whey protein high in protein and high in leucine(HPHL) compared to soy protein high in protein and low in leucine(HPLL) in osteopenic patients in a randomized controlled intervention study.

The investigator hypothesize that HPHL will increase physical function and the ratio muscle mass / fat mass in this condition.

With an increase in the older population in Denmark and most other countries there is an increase in the rate of patients with age related bone and muscle weakness. Proteins with a high content in ketogenic amino acids e.g. leucine have been investigated in relation to these conditions. Generally acute studies in animals and some in human have been conducted and have demonstrated positive effects in relation to prevention and treatment of bone and muscle weakness. We want to investigate these tendencies with supplementation of proteins in a randomized, blinded, 4 month intervention study with three arms - 1) the control group. 2) soy protein(high protein, low leucine). 3) Whey protein(high protein, high leucine). To increase any possible effect of the supplementation the subjects will complete a resistance training program concurrently. The study will focus on the anabolic properties of the ketogenic amino acids in animal whey protein compared to vegetable soy protein.

The investigator will study changes in:

• Gait speed related to muscle strength
• Walk distance in a Six-minute walk test related to sub maximal physical capacity
• Body composition (LBM/FM ratio) by a DEXA-scanner
• Biochemical markers on bone metabolism
• Bone-mineral-density(BMD) and -content(BMC)(DEXA scans)
• Muscle strength
• Body balance
• Protein and amino acid balance
• Nitrogen balance
• Gene-expression in muscle tissue
• Biochemical markers on fat- sugar- and protein-metabolism
• Biochemical markers on inflammation
• Blood pressure
• Insulin sensitivity by HOMA index
• Estimated maximal physical capacity by a bicycle ergometer test.

The perspective in this study is to develop a nutritional supplement with a high content of ketogenic amino acids (e.g. Leucine) that can be useful and beneficial in treatment and prevention of patients with bone and muscle weakness.

Inclusion Criteria:

• Osteopenia defined as BMD T-score <-1

Exclusion Criteria:

• Vitamin D deficiency defined as 25-hydroxyvitamin D (25-OH-D) below 30 nmol/l.
• Liver and kidney disease.
• Known diabetes or Hgb1c ≥6,5% (≥48mmol/l).
• Severe heart disease (NYHA-Class >2).
• Oral corticosteroid treatment within the last 3 month.
• Anamnestic information of hip fracture or vertebral fracture.
• Any antiosteoporotic treatment.
• participation in other intervention studies within the last 4 weeks.