Vitamin D May Shift Calories Toward Muscle Instead of Fat

Recent findings suggest that high-dose vitamin D supplementation may influence how surplus calories are stored — promoting muscle gain instead of fat accumulation.

A study published in May 2024 investigated the effects of different doses of vitamin D on strength, muscle mass, fat mass, and energy expenditure in mice.

Results

The researchers divided the mice into three groups: one received no vitamin D supplementation, the second received a standard dose, and the third received a high dose.

As the doses were increased, increases in grip strengths were recorded.

While no differences in muscle mass were observed between the control and normal-dose groups, the high-dose vitamin D group showed increased muscle mass and reduced fat mass.

These results of statistical testings (ANOVA) suggest that high-dose vitamin D may redirect calorie storage toward muscle growth rather than fat, supporting improvements in strength without necessarily altering body weight.

Mechanism

The study attributed these effects to the modulation of leptin and myostatin signaling pathways:

• Leptin is a hormone secreted by fat cells that suppresses appetite and increases energy expenditure through its action on the brain.

• Myostatin is secreted by muscle cells and acts as a negative regulator of muscle growth.

High-dose vitamin D appeared to increase leptin sensitivity, leading to higher daily energy expenditure, while simultaneously suppressing myostatin, thereby removing a key barrier to muscle development. This dual effect may explain the observed increase in lean mass and reduction in fat mass.

Conclusion

Although these findings are intriguing, it is important to emphasize that the study was conducted only in mice, and the long-term effects in humans remain unknown. Moreover, excessive vitamin D intake can pose serious health risks, including kidney damage, cardiovascular issues, and hormonal or metabolic imbalances.

Until further human research is conducted, the use of high-dose vitamin D as a performance or body composition strategy should be approached with caution.

Reference

Roizen J, Long C, Casella A, Nguyen M, Danahy L, Seiler C, Lei M, Mark J. High dose dietary vitamin D allocates surplus calories to muscle and growth instead of fat via modulation of myostatin and leptin signaling. Res Sq [Preprint]. 2024 May 8:rs.3.rs-4202165. doi: 10.21203/rs.3.rs-4202165/v1. PMID: 38766160; PMCID: PMC11100886.