Designing Nutrition Studies for Long COVID and Related Infection-Associated Chronic Illness: Qualitative Insights From a Patient-Reported Evaluation of Ketogenic Metabolic Therapy - PMC Skip to main content An official website of the United States government Here's how you know Here's how you know Official websites use .gov A .gov website belongs to an official government organization in the United States. Secure .gov websites use HTTPS A lock ( Lock Locked padlock icon ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites. Search Log in Dashboard Publications Account settings Log out Search… Search NCBI Primary site navigation Search Logged in as: Dashboard Publications Account settings Log in Search PMC Full-Text Archive Search in PMC Journal List User Guide PERMALINK Copy As a library, NLM provides access to scientific literature. 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Learn more: PMC Disclaimer | PMC Copyright Notice J Patient Exp . 2026 Apr 13;13:23743735261442541. doi: 10.1177/23743735261442541 Search in PMC Search in PubMed View in NLM Catalog Add to search Designing Nutrition Studies for Long COVID and Related Infection-Associated Chronic Illness: Qualitative Insights From a Patient-Reported Evaluation of Ketogenic Metabolic Therapy Dana Dharmakaya Colgan Dana Dharmakaya Colgan , PhD 1 Helfgott Research Institute, National University of Natural Medicine, Portland, OR, USA 2 Department of Neurology, Oregon Health and Science University, Portland, OR, USA Find articles by Dana Dharmakaya Colgan 1, 2, ✉ , Lita Buttolph Lita Buttolph , PhD, DSOM, MS 1 Helfgott Research Institute, National University of Natural Medicine, Portland, OR, USA 2 Department of Neurology, Oregon Health and Science University, Portland, OR, USA Find articles by Lita Buttolph 1, 2 , Tabitha Grow Tabitha Grow , BS 1 Helfgott Research Institute, National University of Natural Medicine, Portland, OR, USA Find articles by Tabitha Grow 1 , Diane D Stadler Diane D Stadler , PhD, RD 3 Department of Medicine and Graduate Programs in Human Nutrition, Oregon Health and Science University, Portland, OR, USA Find articles by Diane D Stadler 3 , Mary Ruddick Mary Ruddick , MS, MS 4 Enable Your Healing LLC, Austin, TX, USA Find articles by Mary Ruddick 4 , Todd E Davenport Todd E Davenport , DPT, PhD, MPH 5 Department of Physical Therapy, School of Health Sciences, University of the Pacific, Stockton, CA, USA 6 Workwell Foundation, Santa Rosa, CA, USA Find articles by Todd E Davenport 5, 6 , Heather Zwickey Heather Zwickey , PhD 1 Helfgott Research Institute, National University of Natural Medicine, Portland, OR, USA Find articles by Heather Zwickey 1 Author information Article notes Copyright and License information 1 Helfgott Research Institute, National University of Natural Medicine, Portland, OR, USA 2 Department of Neurology, Oregon Health and Science University, Portland, OR, USA 3 Department of Medicine and Graduate Programs in Human Nutrition, Oregon Health and Science University, Portland, OR, USA 4 Enable Your Healing LLC, Austin, TX, USA 5 Department of Physical Therapy, School of Health Sciences, University of the Pacific, Stockton, CA, USA 6 Workwell Foundation, Santa Rosa, CA, USA ✉ Dana Dharmakaya Colgan, PhD, Department of Neurology, Oregon Health and Science University; Helfgott Research Institute, National University of Natural Medicine, Portland, OR, USA. Email: [email protected] Collection date 2026. © The Author(s) 2026 This article is distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 License ( https://creativecommons.org/licenses/by-nc/4.0/ ) which permits non-commercial use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access page ( https://us.sagepub.com/en-us/nam/open-access-at-sage ). PMC Copyright notice PMCID: PMC13080129 PMID: 41993604 Abstract Background Long COVID affects over 400 million people worldwide and has no FDA-approved treatments. Patients often rely on self-directed strategies, making their lived experiences an essential, yet underutilized, source of evidence. Ketogenic metabolic therapy (KMT) has demonstrated mechanisms relevant to Long COVID, including improved mitochondrial energy production, reduced oxidative stress, and modulation of inflammation, but remains underexplored. Methods We conducted a cross-sectional, mixed-methods study of adults who completed Enable Your Healing , a 12-week virtual program integrating KMT with lifestyle components. Recruitment emails were sent to 194 participants; 41 completed the online REDCap survey. Quantitative data were summarized descriptively. Qualitative data were analyzed using conventional content analysis. Results Participants (mean age 41; 90% female) reported diagnoses including postviral dysautonomia, myalgic encephalomyelitis/chronic fatigue syndrome, and Long COVID. Four themes emerged: program benefits, challenges, recommendations, and scientific considerations. Key insights included the value of multicomponent synergy, extended duration, and prioritization of functional outcomes. Conclusion Findings suggest nutrition trials for infection-associated chronic illnesses, including Long COVID, should consider incorporating longer intervention periods, multicomponent design, patient-centered outcomes, lived-experience integration, and tailored supports to optimize feasibility and impact. Keywords: Long COVID, Me/CFS, ketosis, nutrition, study designs, patient-reported evaluation, qualitative study Introduction Long COVID, also referred to as postacute sequelae of SARS-CoV-2, is an infection-associated chronic illness (IACI) that affects more than 400 million individuals worldwide 1 and has generated trillions of dollars in economic losses due to disability, reduced productivity, and healthcare utilization. 2 , 3 It is a heterogeneous, multisystem condition that can present with more than 200 symptoms, across all organ systems; however, several overlapping phenotypes have emerged. Two well-characterized phenotypes within Long COVID populations include postviral myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) 2 and dysautonomia, an umbrella term encompassing disorders characterized by chronic maladaptive responses within the autonomic nervous system and disruptions in circadian regulation. 4 One prominent dysautonomia subtype is postural orthostatic tachycardia syndrome (POTS), characterized by excessive heart rate increase upon standing, orthostatic intolerance symptoms, and chronic autonomic dysfunction in the absence of orthostatic hypotension. In the United States alone, fewer than 10% of patients report full recovery from Long COVID at 2 years postinfection. 5 Despite its staggering prevalence and burden, there are no FDA-approved treatments, leaving patients to experiment with self-directed strategies. In this context, patients’ lived experiences of interventions constitute a critical, yet often overlooked, form of evidence to inform future clinical research. One intervention of increasing interest is ketogenic metabolic therapy (KMT), a dietary strategy that shifts metabolism from glycolysis to ketosis to produce β-hydroxybutyrate (BHB) as an alternative fuel source for high-energy tissues including the brain, heart, and skeletal muscle. KMT has demonstrated multiple mechanistic effects relevant to Long COVID and related conditions, including improved mitochondrial energy production, 4 reduced oxidative stress and modulation of inflammatory pathways, 6 neuroprotection, 7 microbiome support, 8 and enhanced immune function. 9 Originally established as a therapy for drug-resistant epilepsy, 10 KMT has since been investigated in other neurological and metabolic conditions such as Parkinson's and Alzheimer's disease, 11 type 2 diabetes, 12 obesity, 13 and cancer. 14 Emerging preclinical work also suggests potential benefit in acute viral infections, including SARS-CoV-2, 15 but its application to Long COVID and other IACIs remains underexplored. Designing effective interventions for Long COVID and related IACIs requires research frameworks that center lived experience at the earliest stages of study conceptualization. 16 , 17 Patients bring critical knowledge about symptom patterns, intervention tolerability, barriers to implementation, and definitions of meaningful recovery. Embedding lived experience into trial design enhances feasibility, acceptability, and real-world applicability, while strengthening trust in the research process. 9 , 11 To address the lack of patient-informed guidance for designing nutrition and lifestyle trials in Long COVID and other IACI populations, we engaged stakeholders who had completed a community-based, virtually delivered KMT plus lifestyle (KMT-LS) program. This multicomponent program was developed for individuals with IACI, including postviral ME/CFS, dysautonomia/POTS, and Long COVID. Because ME/CFS and dysautonomia/POTS share overlapping symptom burden (eg, fatigue, postexertional symptom exacerbation, cognitive dysfunction, autonomic instability) and proposed pathophysiologic mechanisms (eg, immune dysregulation, autonomic and circadian disruption, mitochondrial dysfunction), we included participants with these diagnoses to inform Long COVID trial design and capture patient-derived considerations relevant to heterogeneous postviral presentations. The present study does not assess symptom reduction. Instead, the aim of this study was to engage stakeholders to identify key elements necessary for designing and implementing a clinical trial of a virtually delivered KMT intervention for individuals with Long COVID and related IACIs. Method Study Design This cross-sectional study analyzed data from online surveys administered via the Research Electronic Data Capture (REDCap) platform. Recruitment emails containing a survey link were sent to 194 adults (≥18 years) who completed the 12-week, online KMT-LS program between June 2022 and June 2024. A follow-up recruitment email was sent 1 week later. The survey closed 3 weeks after sending the initial email. To prevent duplicate submissions, participants provided their date of birth, personal email, and the last 4 digits of their Social Security number. All participants provided electronic informed consent and received a $50 gift card. Incomplete surveys were excluded from the analysis. The response rate was calculated as the quotient of completed surveys and total recruitment emails sent. This study was approved by the Institutional Review Board at the Helfgott Research Institute and National University of Natural Medicine. KMT-Lifestyle Intervention Enable Your Healing is a community-based, virtual educational program created for individuals living with dysautonomia, ME/CFS, and Long COVID. The 12-week program combines KMT with circadian rhythm entrainment, mindfulness practices, and when clinically appropriate, gentle recumbent exercise and hormetic therapies. The virtual program was delivered via 3 weekly conference calls. Dietary instruction emphasized a structured ketogenic approach of low carbohydrate intake, moderate protein, and high fat consumption to promote a metabolic transition from glycolysis to ketosis, and the generation of BHB as an alternative energy source. Participants were encouraged to adopt an intermittent eating schedule, eliminate added sugars, and supplement with Benfotiamine, a synthetic, fat-soluble derivative of thiamine (Life Extension, Fort Lauderdale, FL). Recommended electrolyte support included daily intake of magnesium citrate/malate, potassium citrate, sodium bicarbonate, and sodium chloride. Circadian entrainment included consistent wake times (7:00 a.m.), immediate morning light exposure, consistent mealtimes, and limiting blue light 2 hours before sleep. Mindfulness-based practices included mindful eating, 60 min of daily meditation, and gratitude exercises. Participants were coached in mindful nonreactivity to reduce cognitive reactivity and enhance emotional regulation. These practices were intended to improve parasympathetic tone and psychological resilience rather than directly treat the underlying disease pathology. If clinically appropriate, gentle recumbent biking and hormetic therapies (eg, cold therapy, heat exposure) were invited. Delivery of the program was facilitated by a nutritional therapist and health coaches. One weekly online session was led by the medical nutritionist and focused on KMT and nutritional education. A second weekly session, facilitated by a health coach, emphasized circadian rhythm entrainment and the establishment of consistent daily routines. The third weekly session, also led by a health coach, centered on mindfulness-based practices, mindset, and psychological resilience. In addition, bi-monthly group sessions incorporated guided breathwork practices. Each session lasted at least 60 min. Participants were advised to maintain the nutritional and lifestyle strategies for 12 to 24 months, or until remission of symptoms was achieved. Core components of the intervention are summarized in Table 1 . Table 1. Three Core Components of Enable Your Healing. Nutritional Therapy Macronutrient distribution of daily food intake 60-80 g of protein 100 or more grams of fat 15-20 g or fewer of carbohydrate Modifications were made based patients’ need to increase, maintain, or decrease weight. Energy intake was approximately 70% fat, 25% protein, and 5% carbohydrate. Low levels of plant toxins Low levels of lectins, oxalates, and endocrine-disrupting glycoalkaloids, such as solanine and phytoestrogens Eliminate Sugar Daily supplements Benfotiamine—fat-soluble form of Vitamin B1 (starting with 250 mg/day and titrating up, as tolerated, to 2000 mg/day) Other Vitamin Bs and Vitamin C (as clinically relevant) Two tablespoons of cod liver oil Daily supplementation of electrolytes Magnesium citrate/malate (3000 mg) Potassium citrate (3000 mg) Sodium bicarbonate (1200 mg) Sodium chloride (1000 mg). Two to three meals per day Four to 6 cups of homemade meat broth daily with cooked vegetables. Entrain the circadian rhythm Exposure to bright morning light Reduced blue light in evening Intermittent fasting Time restricted eating Consistent routine of waking, eating, and sleeping every day Mindfulness-based strategies Mindful breathing techniques Nonreactive awareness of negative thoughts Reframing negative thoughts Body scans Mindful eating Open in a new tab Data Collection The electronic survey posed open-ended questions to participants, which included: “What was most difficult about the program?” “Do you have any concerns about the program?” “Did you experience any adverse events during the program?” “Tell us about the personal modifications during the program,” “What else would you like to share with us?” and “What are some things you would like scientists to consider when evaluating this program's effects on health?” Questions regarding symptom improvement are not described in this article. Data Analyses Quantitative data were analyzed using summary statistics in SPSS-29 ® (IBM Corp., Armonk, New York, US). Qualitative data from open-ended survey questions were analyzed using conventional content analysis, 18 an inductive approach where coding categories are derived directly from the text. Three researchers (DDC, LB, TG) independently performed open coding on the raw data to identify emergent themes and subthemes. The team then engaged in iterative consensus meetings to reconcile coding discrepancies and establish a standardized codebook, which was subsequently applied to the full dataset to ensure consistency. During the final stage of thematic synthesis, the first author reviewed all excerpts within each code, merging overlapping categories and subdividing others into discrete subcategories. Precise operational definitions were developed for all final categories to ensure analytic rigor and interpretative clarity. Results Participant Characteristics A total of 45 individuals responded to the recruitment email, 44 of whom provided consent. Of those who consented, 3 did not complete the survey, resulting in a final sample size of 41 (37 female). With a 21% response rate, the international sample included participants from 4 countries: the United States, Germany, England, and Sweden. Participants in the United States resided in 22 states across 5 regions (Northeast, Southeast, Midwest, Southwest, and West). The mean age was 41 years ( SD = 10). The sample was predominantly White (88%) and represented diverse educational backgrounds, annual household incomes, and geographic locations. At the start of the intervention, 71% of participants reported a diagnosis of dysautonomia presenting as POTS, nearly 60% reported ME/CFS, 42% reported migraines, 34% reported mast cell activation syndrome (MCAS), 34% reported an autoimmune disease, and 82% reported a chronic pain condition. Although only 32% of participants reported a formal diagnosis of Long COVID, 70% reported that their illness onset (eg, ME/CFS, POTS, MCAS, or autoimmune disease) occurred after 2020. Approximately 83% reported a history of COVID-19 infection. Among those who had been infected, reinfection was universal: 50% reported 1 reinfection, 30% reported 2, 8% reported 3, and nearly 12% reported 5 or more reinfections. Qualitative Analysis Qualitative analysis of open-ended survey responses generated 4 major themes: (1) program benefits, (2) program challenges, (3) program recommendations, and (4) scientific considerations. Within each theme, multiple subthemes were identified and are illustrated below with representative quotations ( Table 2 ). Questions about symptom improvement were not included in the present study and symptom change is not evaluated in this article. Table 2. Main Themes, Subthemes, and Participant Quotations From Qualitative Data Analysis. Themes Subthemes Quotations Program benefits Sense of community The continued support in the group calls and community platform with access to people's questions and comments is extremely valuable and helpful. I'm so grateful for the support of the program and how it helped me feel so much less alone in the intense hell that was life with dysautonomia. Even though I needed additional interventions beyond the 12 weeks, it was a solid place from which to start my deep body reset, and provided hope and community when I desperately needed it. Validation of medical illness It was unbelievably helpful to have example of humanness, perseverance, healing, thriving, radiating, smiling, living, and overcoming illness. First time on my healing journey that I felt picked up and truly understood. The assurance that the body knows what it does. That I cannot fail. It was super helpful that it wasn't around “trauma” or my psychological weakness to explain all my misery. But to receive the scientific physiological context of why I'm experiencing certain things. “It's not my fault, but I, only I can and have to take full responsibility for my life.” Increased health efficacy I love that I have lifelong access to all of the educational material. I loved having all the information there from the get-go. It was very empowering to be able to take that and heal myself. Start of healing journey I was totally clear about the fact that it's a long-term journey and not a quick fix. Even though I needed additional interventions beyond the 12 weeks, it was a solid place from which to start my deep body reset, and provided hope and community when I desperately needed it. I followed the 12-week program for 2 years and I over the course of the 2+ years I have continued to improve very slowly. Multicomponent intervention They (individual components) all work together. The combination of all of the components—understanding that it is not one thing, but the consistency of doing many things is the path to recovery. Program challenges Implementation Time and effort Implementing everything in such a short time. Time frame made some aspects feel rushed. Attending all the calls and navigating all the content in such a short period of time was hard. When it started (first 3 months), I was so compromised cognitively, socially, and energetically that I could not attend or really take advantage of the many calls during the week. When I finally began to improve in those areas, the calls were long over and connecting with both other rebels and the practitioners was very limited in comparison. Logistics Implementation when not feeling well. For me it was pretty hectic to attend to all the zoom calls and still trying to work, It made me very tired. Information overload I am so grateful that the information and program was somewhat self-paced. My biggest challenge was information overload. I love that I have lifelong access to all of the educational material, as well as continued support. I still have a ton of info to work through in the portal. Access/cost The cost of the program is so challenging for someone not able to work or working part time. Trust Fully trusting the program (after so many interventions that failed) and relaxing into the routine. Nonlinear nature of metabolic adaption The program may increase the intensity of the symptoms and can cause you to question whether it works or is just making you sicker. The symptoms worsened and were stubborn for many months; it was NOT a linear process but took many months to get past die offs and being able to “tolerate” them (detox pathways improving.) Program recommendations Increased personalization I could have used more 1:1 support to navigate personal modifications. My body really struggled with tolerating recommended supplements and dosing as well as managing/balancing keto. Postprogram supports I feel like the program set a good foundation, but the 12-week mark was a crucial time for more individualized treatment such as supplements and how to rebuild good bacteria, and die off symptoms or new weird symptoms. Personally, having the meetings extended would be helpful. It felt like being dropped off a cliff when the meetings stopped at 12 weeks. Adverse effects happen long after and it's nice to have support. Duration and dosing I think the program should go to 6 months. The 3 to 6-month timeframe was very hard and there was an increase in symptoms and had little to no access to get advice on how to get through it. Participant navigation A written outline of things to expect and typical time frame (eg, 2 years). A brief overview separate for both providers and friends and family. Scientific consideration Measuring endpoints Three-month intervals of assessment for at least a year Functional capacity assessment Functionality before and after would be HUGE! How long were you bedridden prior? How often are you bed ridden now? How dependent were you before versus after? How able are you to accomplish your goals after compared to before? Adherence to complex interventions How to know if people were complying with all or just some of the program (some people may report what they believe they should be doing) Responder stratification Why do some people recover and not others? Do baseline diagnoses predict treatment outcomes? Baseline characterization Make sure you have a good description of participants’ baseline functioning, symptoms, and diagnoses and group accordingly. Open in a new tab Theme 1. Program Benefits. Participants highlighted multiple benefits of the KMT-LS program, outside of symptom improvement, emphasizing sense of community, validation of medical illness, increased health efficacy, initiation of a healing journey, and the value of multicomponent interventions. Sense of community: Community was consistently described as a source of support, with participants noting that group calls and the online platform reduced isolation and fostered hope. Participant 29 stated the program, “helped me feel so much less alone in the intense hell that was life with dysautonomia.” Validation of illness: Respondents described relief in receiving scientific, physiological explanations rather than psychosomatic attributions. Participant 12 noted her appreciation that the program was not “around ‘trauma’ or my psychological weakness … but instead I received the scientific physiological context of why I’m experiencing certain things.” Increased health efficacy: Participants noted the appreciation for lifelong access to educational materials and a new sense of empowerment to make health changes. Participant 3 stated, “I loved having all the information there from the get-go. It was very empowering to be able to take that and heal myself.” Synergistic value of multicomponent interventions : Participants reported benefits arose from the combination of elements, rather than isolated elements. Participant 5 stated, “The combination of all the components (was important). Understanding that it is not one thing, but the consistency of doing many things, is the path to recovery.” Start of healing journey: For many, the program marked the start of a healing journey. Participant 37 remarked, “This program was a solid place from which to start my deep body reset and provided hope and community when I desperately needed it.” Theme 2. Program Challenges. Participants described several barriers to implementation, organized into subthemes of time and effort, logistics, information overload, access/cost, trust, and the nonlinear nature of healing, including challenges associated with early metabolic adaptation to ketosis and fluctuating symptom presentations. Time and effort: Some participants noted difficulty managing the program's intensity while acutely symptomatic. Participant 23 described, “When it started (first 3 months), I was so compromised cognitively, socially, and energetically that I could not attend or really take advantage of the many calls during the week. When I finally began to improve in those areas, the calls were long over and connecting with other clients, and the practitioners, was very limited in comparison.” Logistics : Coordinating multiple calls while balancing daily responsibilities was described as “hectic” and fatiguing. Participant 18 noted, “For me it was pretty hectic to attend to all the zoom calls and still trying to work. It made me very tired.” Information overload : While participants valued the breadth of content, many noted that the volume of material was initially overwhelming, though mitigated by ongoing portal access. Participant 6 stated, “I am so grateful that the information and program was somewhat self-paced. My biggest challenge was information overload. I love that I have lifelong access to all of the educational material, as well as continued support. I still have a ton of info to work through in the portal.” Access/cost: Program cost was a barrier for those unable to work due to illness. Participant 14 simply stated, “The cost of the program is so challenging for someone not able to work or working part time.” Trust: Participants described difficulty “relaxing into the routine” after previous failed interventions. Participant 32 noted he had a hard time, “fully trusting the program after so many interventions had failed.” Nonlinear nature of metabolic adaptation : Participants frequently described recovery as a nonlinear process characterized by transient symptom exacerbations. Seventy-two percent of participants reported mild adverse events, including flu-like symptoms (eg, fever, nausea), fatigue, and neurological or gastrointestinal shifts. These events were generally consistent with “keto flu” or early metabolic adaptation. Theme 3. Program Recommendations. Participants recommended greater personalization, extended postprogram supports, longer duration, and improved participant navigation. Personalization : Some respondents desired more one-on-one guidance, especially to adjust supplement regimens or balance ketogenic protocols. Participant 1 wrote, “I could have used more 1:1 support to navigate personal modifications. My body really struggled with tolerating recommended supplements and dosing as well as managing/balancing keto.” Postprogram supports : Many noted that the 12-week cutoff felt abrupt, requesting extended guidance during later phases of recovery when new or persistent symptoms emerged. Participant 7 stated, “I feel like the program set a good foundation, but the 12-week mark was a crucial time for more individualized treatment such as supplements and how to rebuild good bacteria, and die off symptoms or new weird symptoms.” Duration and dosing : Participants frequently recommended extending the program to 6 months or longer, aligning with their experience of prolonged recovery trajectories. Participant 7 also wrote, “I think the program should go to 6 months. The 3 to 6-month timeframe was very hard and there was an increase in symptoms and had little to no access to get advice on how to get through it.” Participant navigation : Finally, suggestions included written outlines of expected milestones and timelines to normalize setbacks and assist providers, patients, and families in understanding the healing process. Theme 4. Scientific Considerations. Respondents provided patient-centered insights to inform future clinical trial design. Measuring endpoints : Respondents recommended extended longitudinal tracking, suggesting assessments at 3-month intervals for at least 1 year to capture the full trajectory of recovery. Functional capacity assessment: In addition to capturing symptom improvement, participants suggested also assessing functional capacity. Participant 8 wrote, “Please assess functionality before and after would be HUGE! How long were you bedridden prior? How often are you bedridden now? How dependent were you before versus after? How able are you to accomplish your goals after compared to before?” Adherence to complex interventions: Several individuals emphasized the need to evaluate adherence to complex interventions, given variability in uptake of different program components. Participant 11 asked, “How will you know if people were complying with all or just some of the program, as some people may report what they believe they should be doing?” Responder stratification : Patients highlighted the importance of distinguishing responders from nonresponders, including exploring whether baseline diagnoses predict outcomes. Baseline characterization: Participants recommended detailed baseline characterization of illness severity, comorbidities, and functional limitations to guide subgroup analyses. Participant 14 wrote, “Make sure you have a good description of participants baseline functioning, symptoms, and diagnoses, and group accordingly.” Discussion This study explored patient-reported experiences with a community-based, virtual KMT intervention among individuals reporting Long COVID and related IACIs. Although 70% of participants reported illness onset after 2020, only 32% endorsed a formal diagnosis of Long COVID. This discrepancy likely reflects limited access to Long COVID specialty clinics, low public and clinician awareness, and diagnostic inequities documented throughout the pandemic. Consequently, a substantial number of individuals with symptoms clinically consistent with Long COVID remain undiagnosed. These findings offer critical insights into perceived benefits, implementation barriers, and patient-derived recommendations essential for the design of future nutrition trials. Such considerations are particularly vital given the high prevalence of ME/CFS and dysautonomia phenotypes within the Long COVID population. Our results reinforce the need for patient-centered approaches in nutrition research. Participants consistently emphasized the importance of synergy across dietary, lifestyle, and psychosocial components, rather than any single intervention strand. This perspective aligns with the growing recognition in chronic illness research that multicomponent interventions may produce additive or synergistic effects by engaging multiple biological systems simultaneously. 19 , 20 Increasing scientific evidence suggests that IACIs, like Long COVID, arise from broad interconnectivity across physiological pathways, health behaviors, social connectedness, and environmental influences. 17 – 20 Accordingly, developing and evaluating complex interventions that integrate multiple treatment modalities, an approach increasingly used in fields such as integrative pain care, may be particularly well-suited for Long COVID and related IACIs. Nutrition studies in this population should therefore consider integrative, whole-person frameworks that incorporate multicomponent intervention strategies. Another key insight relates to program duration and dosing. Most participants perceived the 12-week intervention as too short, recommending extensions to 6 months or longer. This suggests that nutrition studies should be designed with adequate length to capture the nonlinear, often protracted recovery trajectories observed in Long COVID and related IACIs. Short-term trials may underestimate efficacy by failing to capture delayed or gradual improvements, while also overlooking adverse events that may emerge over time. In this study, participants emphasized the importance of assessing overall functionality, independence, and the ability to pursue personal goals in addition to symptom reduction. Their perspectives highlight that functioning and symptoms are closely interconnected, and that both domains are meaningful indicators of recovery/improvement. Such insights underscore the value of incorporating lived experience from the earliest stages of study design. 16 , 17 , 21 , 22 By embedding patient expertise into decisions about endpoints, dosing schedules, and safety monitoring, nutrition researchers can improve the ecological validity of trial protocols and ensure alignment with real-world recovery priorities. Moreover, participant suggestions to stratify cohorts by baseline diagnosis, comorbidities, and functional status reflect an urgent need to tailor trial design to the heterogeneity of Long COVID presentations. This has been discussed at length. Stratifying long COVID patients into more homogenous subgroups would facilitate the understanding of specific long COVID presentations which would lead to a better understanding of the heterogeneous pathophysiology and more personalized patient care. The identification and validation of subtypes is challenging due to the need for large cohorts to capture patient heterogeneity, the expense of deep phenotyping, and multiple confounding factors affecting measured outcomes. 23 – 25 Participants identified several barriers to implementation, including cognitive impairment, time demands, cost, and difficulties trusting new interventions following prior failed treatments. These barriers carry important implications for future nutritional therapy studies. To optimize adherence, participants recommended: (1) streamlining intervention delivery to reduce cognitive load; (2) providing financial supports or exploring insurance coverage pathways to improve access; and (3) incorporating trust-building strategies, including transparent communication and peer support to address skepticism among individuals with histories of medical invalidation and years of failed interventions. Participants also frequently described a nonlinear healing process, highlighting the need for investigators to prepare both participants and providers for symptom fluctuations and potential temporary exacerbations, such as those reported during early ketogenic adaptation (“keto flu”). Adverse events reported were common but generally mild, self-limited, and consistent with the transient constellation of symptoms associated with early metabolic adaptation. These effects may influence compliance and tolerability and should be proactively considered in trial design. Explicit discussion of expected symptom trajectories, coupled with flexible pacing and supportive monitoring, may help sustain participant engagement and reduce dropout. This study has several strengths. It is among the first to evaluate patient-reported experiences of a virtually delivered KMT-lifestyle intervention for individuals with IACI, including Long COVID, ME/CFS, and dysautonomia. Inclusion of participants with Long COVID, alongside common Long COVID phenotypes (postviral ME/CFS and dysautonomia/POTS), allows the study to capture trial design considerations across a spectrum of postviral presentations frequently encountered in Long COVID care. The study captured rich qualitative insights, providing a more comprehensive understanding of patient perspectives. The international sample, spanning multiple regions in the United States and several countries, enhances the relevance of findings across diverse contexts. Importantly, the study explicitly integrated lived experience as a source of evidence, generating practical guidance for the design of future nutrition trials. Several limitations should also be noted. The cross-sectional design and reliance on retrospective self-report preclude conclusions about causality. The modest sample size ( n = 41) and 21% response rate raise the possibility of selection bias, with individuals experiencing greater benefit potentially more likely to participate. Further, Long COVID status was not assessed with a standardized case definition or independently verified; as a result, we cannot precisely quantify how many participants met formal Long COVID criteria. The sample reflects an IACI community with high representation of ME/CFS and dysautonomia/POTS, phenotypes frequently observed in Long COVID, so conclusions are best interpreted as patient-centered guidance for Long COVID trial design, not as evidence from a confirmed Long COVID-only cohort. Despite these limitations, the findings provide valuable early evidence to guide the development of longer, more personalized, and patient-centered nutrition interventions for Long COVID and related postviral conditions. Conclusion Together, these findings suggest that future nutritional trials for Long COVID and related IACIs should: (1) Extend study duration to capture gradual recovery trajectories; (2) Utilize multicomponent designs to reflect patient-perceived synergy; (3) Balance functional and quality-of-life outcomes, not just biological endpoints; (4) Incorporate lived experience from the outset, ensuring that study design, outcomes, and safety protocols are cocreated with patients; and (5) Incorporate personalization and postprogram supports to enhance feasibility. By adopting these strategies, nutritional research in Long COVID and related IACIs can advance toward interventions that are mechanistically grounded, patient-centered, and clinically impactful. Acknowledgments We thank the research participations who contributed their time, energy, and insight to make this project possible. We also extend our gratitude to the many providers and health coaches. Finally, we thank the millions of patients with infection-associated chronic conditions who continue to advocate, inform, and drive the science forward. Thank you. Footnotes Author Contributions: Dana Dharmakaya Colgan: conceptualization, survey development, data curation, visualization, writing, and editing; Diane D. Stadler: writing and editing; Tabitha Grow: data analyses and editing; Heather Zwickey: writing and editing; Mary Ruddick: intervention, survey design, recruitment, and editing; Todd E. Davenport: writing and editing. The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. Disclosures: DDC: no disclosures; LB: no disclosures; DS: no disclosures; TG: no disclosures; MR: owner of Enable Your Healing , LLC and nutritionist who developed the Enable Your Healing program; HW: no disclosures; TD: no disclosures. Data Availability Statement: Data is available at request. Ethical Approval: Our study was approved by the National University of Natural Medicine Institution Review Board (IRB # HZ102024 ). All participants provided written informed consent prior to enrollment in the study. Funding: The authors thank the National Institute of Health for grant funding NIH (Grant No. AT008924-08). Statement of Human and Animal Rights: There were no procedures involving animals. ORCID iDs: Dana Dharmakaya Colgan https://orcid.org/0000-0002-6806-1542 Lita Buttolph https://orcid.org/0000-0002-3543-2570 Diane D. Stadler https://orcid.org/0000-0002-4718-2054 References 1. Chen B, Julg B, Mohandas S, Bradfute SB. Viral persistence, reactivation, and mechanisms of long COVID. eLife. 2023;12:e86015. [ DOI ] [ PMC free article ] [ PubMed ] [ Google Scholar ] 2. Bartsch SM, Chin KL, Strych U, et al. The current and future burden of long COVID in the United States. J Infect Dis. 2025;231(6):1581–1590. [ DOI ] [ PMC free article ] [ PubMed ] 3. 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