Summary: In an 8-week trial in women with overweight or class I obesity, an energy-restricted ketogenic diet altered amino acid metabolism, raising branched-chain and α-aminobutyric acids and lowering several others compared with a standard diet; these are mechanistic biomarker changes, not clinical outcomes.
PICO Summary
| Element | Detail |
|---|---|
| Population | 80 women aged 18–45 with overweight or class I obesity (BMI 25.5–35), 66 analysed; 8-week randomised controlled trial (KETO-MINOX), Poland. |
| Intervention | An energy-restricted Mediterranean-type ketogenic diet (~1750 kcal/day) via food catering. |
| Comparison | A standard isocaloric diet (~1750 kcal/day) via food catering. |
| Outcome | Independent of diet, weight loss raised α-aminobutyric acid and lowered proline, glutamate, and tyrosine. The ketogenic diet specifically lowered alanine, methionine, threonine, and tryptophan and raised branched-chain amino acids and α-aminobutyric acid versus standard diet, with higher urinary excretion of branched-chain and β-aminoisobutyric acids. The authors suggest possible implications for inflammation, oxidative stress, and cardiometabolic risk. |
Expert Commentary
This is a metabolic mechanism study, and its findings are biochemical signatures rather than clinical results, so it should be read for insight into how a ketogenic diet reshapes amino acid handling, not as evidence about health outcomes. The design has real strengths for that purpose, an isocaloric comparison with catered food that controls energy intake, allowing the diet-specific amino acid changes to be separated from the effects of weight loss itself, which the authors did by showing some shifts occurred with weight loss regardless of diet. The branched-chain amino acid elevation is interesting given its associations with insulin resistance, though the meaning here is ambiguous and the authors frame downstream implications for inflammation and oxidative stress only speculatively. The limitations are inherent to scope: a small, all-female, short eight-week study with surrogate metabolomic endpoints and no clinical outcomes, in women without chronic disease. Can I use this with my patients? Not directly. It does not change dietary advice and offers no outcome data to act on, but it adds useful mechanistic context to how ketogenic diets alter metabolism, and I would treat the amino acid shifts as hypotheses for future work rather than anything to communicate to patients as benefit or harm.
References
Drabińska-Fois N, Majcher A, Jagielski P, Borowicz-Skoneczny S, Romaszko J. Alteration in amino acid metabolism after isocaloric, energy-restricted ketogenic diet in women with overweight and obesity: randomized KETO-MINOX trial. Nutrients. 2026;18(2):300. doi:10.3390/nu18020300