BSO Compound Shows Promise in Mimicking Anti-Obesity Effects of Restrictive Diets

A new study published in Aging-US on March 2, 2026, suggests that the compound D, L-buthionine-(S, R)-sulfoximine (BSO) may replicate the fat-loss benefits of a challenging sulfur amino acid-restricted diet (SAAR) without the associated negative effects on bone health.¹ The research, led by Naidu B. Ommi and corresponding author Sailendra N. Nichenametla from the Orentreich Foundation for the Advancement of Science, offers a potential avenue for obesity treatment that doesn’t require strict dietary adherence.

The Challenge of Sulfur Amino Acid Restriction

Sulfur amino acid restriction (SAAR), a diet low in methionine and cysteine, has demonstrated significant anti-obesity effects in animal studies.² However, its practical application in humans is limited due to the difficulty of maintaining such a restrictive diet. This new research explores whether BSO, a compound known to lower glutathione (GSH) levels, could achieve similar results without the dietary constraints.

How the Study Worked

Researchers tested four groups of obese mice on high-fat diets:¹

• A control group receiving a standard diet.
• A group on the SAAR diet.
• A group receiving a regular diet supplemented with BSO.
• Two control groups receiving either no treatment or a supplement that increased GSH levels.

The team used body composition analysis, micro-CT scans, histomorphometry, and biomechanical testing to assess the effects of each treatment.

Key Findings: BSO Replicates Fat Loss Without Bone Loss

The study confirmed that SAAR effectively reduces fat mass but also leads to decreased bone mineral density, increased marrow adiposity, reduced osteoblast numbers, and weakened bone strength.¹ Importantly, BSO treatment resulted in comparable reductions in fat mass and weight gain to the SAAR diet, without causing the detrimental effects on bone health. Supplementation with N-acetylcysteine (NAC) reversed the bone defects associated with SAAR, suggesting a link between cysteine/glutathione restriction and bone loss.

Implications and Future Research

These findings suggest that BSO could be a promising tool for understanding the complex relationship between sulfur amino acid metabolism, fat loss, and bone health.¹ However, the authors emphasize the need for further research, including:

• Investigating the mechanisms by which GSH lowering promotes fat loss although sparing bone.
• Examining the effects of BSO at different ages and in both male and female subjects.
• Conducting long-term safety studies to identify any potential adverse effects before considering clinical development.

The research team cautions that BSO is not yet ready for human therapy and requires extensive preclinical evaluation.¹

Sources

1. Ommi, N. B., et al. (2026). D, L-Buthionine-(S, R)-sulfoximine recapitulates the anti-obesity effects of sulfur amino acid restriction without the associated deleterious effects on bone in male mice. Aging. DOI: 10.18632/aging.206358
2. Ommi, N. B., Mattocks, D. A. L., Kalecký, K., Bottiglieri, T., & Nichenametla, S. N. (2025). Pharmacological recapitulation of the lean phenotype induced by the lifespan-extending sulfur amino acid-restricted diet. Aging (Albany NY), 17(4), 960–981. https://www.aging-us.com/article/206237