A 300-person randomized trial found that four weeks of micronutrient-optimized prepared meals did not reduce visceral fat or change the study’s other primary outcome more than comparison diets. Several cardiovascular and microbiome signals improved, but they remain exploratory.
What changed
Japanese adults were assigned to optimized nutrient-dense meals, a micronutrient-insufficient control diet, or nutrient-matched low-carbohydrate, high-fat meals. Neither optimized diet beat the comparators on the prespecified primary endpoints: visceral fat area and salivary cortisol or melatonin. LDL cholesterol fell in both optimized-meal groups versus control, while systolic blood pressure fell in the low-carbohydrate group. Exploratory microbiome and metabolite changes were also reported.
How strong is the evidence?
This was a peer-reviewed, single-blind human randomized controlled trial with 300 participants. Randomization and controlled meals strengthen the comparison. However, the four-week duration was short, and the favorable cardiovascular findings were secondary endpoints rather than the trial’s main tests.
What remains uncertain
The study did not test heart attacks, diabetes complications or long-term weight control. A lower epigenetic-age measure came from only 10 older men per group and should not be treated as proof of slower aging. Nissin Foods funded the trial, supplied the meals and employed several authors; an independent statistician analyzed the data.
Why it matters
The negative primary result is important: improving micronutrient coverage did not automatically reduce visceral fat within a month. The LDL and blood-pressure signals justify longer independent trials, but not claims that packaged “optimized” meals reverse aging or cardiovascular disease.
Illustrative stock photograph by Louis Hansel on Unsplash; it does not depict the study meals, participants or results.
Sources
Original study in Scientific Reports, published October 3, 2026.
