(P17-24-26) Feasibility of a Very Low Carbohydrate Ketogenic vs Mediterranean Diet Intervention in Older Adults: The POPDIETS‑Aging Pilot Study

Objectives: Aging is accompanied by declines in bone density, muscle mass, and physical function. Ketogenic diets (KD) are studied for selected metabolic and neurological indications, but their feasibility and physiological effects in older adults are not well characterized. The POPDIETS‑Aging pilot study was designed with feasibility as the primary objective and included exploratory musculoskeletal measures for future analyses. A Mediterranean diet (MD), which is consistently associated with healthy aging, served as the comparator.

Methods: This 2‑arm, cluster‑randomized trial enrolled community‑dwelling adults aged 55–80 y with BMI 20– < 35 kg/m² and without major metabolic or musculoskeletal disease. Households were randomized to a modified KD (~1:1 ketogenic ratio) or MD intervention with meal delivery for 6 weeks. Participants received two prepared meals per day, recipes, weekly visits, and a daily fortified nutrition shake plus a multi‑micronutrient supplement. Feasibility outcomes included recruitment yield, retention, and adherence. Diet adherence was assessed by mobile food records, 24‑hour diet recalls, and circulating β‑hydroxybutyrate (BOHB) as a KD biomarker.

Results: Among 468 individuals prescreened, 59 completed in‑person screening, and 12 were eligible and randomized (KD n=6; MD n=6). Two participants in the KD arm were withdrawn by the study team, resulting in completion rates of 67% (KD) and 100% (MD). Adverse events occurred only in the KD arm. Dietary adherence exceeded 85% of study days in both arms. Carbohydrate and fat intakes differed substantially between diet groups, while protein intake did not. BOHB increased at mid‑study in the KD arm by 0.54 mmol/L (95% CI: 0.08, 0.99) but changed by -0.38 mmol/L (95% CI: -0.89, 0.12) thereafter.

Conclusions: Meal delivery supported high adherence to a modified KD. Adverse events occurred only in the KD arm, indicating that studying a KD in older adults requires careful clinical consideration and oversight. These feasibility findings will guide refinement of eligibility criteria, safety monitoring, and protocol design for future trials.

Funding Sources: Older Americans Independence Center and Food Science and Human Nutrition Department, University of Florida.