Fully Remote, Telehealth-based Ketogenic Metabolic Therapy for Long COVID

Acceptability data were measured via participants' perception of treatment suitability using a 5-point Likert scale (e.g., 1 = Not at all helpful; 5 = Extremely helpful). Participants were asked to rate their level of satisfaction with the program, the perceived helpfulness and relevance of the program, and the likelihood of recommending the program to others. Assessment burden was measured using a 5-point Likert scale (1 = Strongly Disagree, 2 = Disagree, 3 = Undecided, 4 = Agree, 5 = Strongly Agree). Participants were asked to rate the burden associated with sourcing food, cooking food, and completing assessment procedures. Further, acceptability was explored via questions pertaining to optimization of the study, including opinions on dosing and duration of the intervention.

Feasibility of the research procedures and remote intervention was evaluated using metrics of enrollment (target sample size n = 10), attrition, population characteristics (e.g., percentage of participants identifying as non-white), completion of data-collection procedures within a 2-week window, amount of missing data, dietary adherence, and safety. The target sample size of 10 was selected to optimize group dynamics for the interactive, group-based components of the ketogenic metabolic therapy intervention, including weekly nutrition calls. Attendance at the weekly nutrition calls was recorded. We assessed adherence to dietary recommendations through participant self-report and objective metabolic data. Participants measured fasting capillary blood β-hydroxybutyrate (BHB) and fasting blood glucose using a commercially available, FDA-registered at-home device (Keto Mojo Meter, Keto Mojo, Inc.).

PROMIS-29 to assess self-reported levels of physical, social, and cognitive functioning, anxiety, depression, pain interference, and sleep disturbance. Each subscale is standardized to a T-score (Mean = 50, SD = 10), where higher scores represent more of the concept being measured (e.g., more anxiety or better physical function). A threshold of 3 T-score points is considered a minimal clinically important difference (MCID) for each subscale

Measured functional capacity using a 12-item self-report questionnaire that assesses the ability to perform specific activities of daily living. Each item is weighted by its metabolic equivalent value, with total scores ranging from 0 to 58.2. Higher scores indicate greater functional capacity and serve as a validated surrogate marker for peak oxygen uptake .

Measures respiratory limitation, which categorizes breathlessness on a 5-point scale (Grade 0-4) based on the level of physical exertion required to elicit shortness of breath. A 1-point increase represents a significant decline in function and is recognized as the MCID.

MAPS is a self-rated, 12-item visual analogue instrument (0-10 per symptom, total 0-120) that measures orthostatic and autonomic burden. Each item scores current symptom burden; higher totals indicate greater symptom severity.

The Bateman Horne Center Good Day/Bad Day Questionnaire is not scored as a symptom-severity index; its two anchors are Hours of Upright Activity (HUA) and the number/proportion of good days, both of which are functional-capacity metrics. More upright hours and a higher good:bad day ratio indicate greater functional capacity and less PEM burden; lower values indicate more severe illness.

Evaluates global life satisfaction using a 5-item instrument that uses a 7-point Likert scale to assess an individual's conscious evaluative judgment of their life. Scores range from 5 (Extremely dissatisfied) to 35 (Extremely satisfied).