Cardiology · Medical Literature
Determinants of Adherence to a Ketogenic Diet in Patients with Heart Failure with Reduced Ejection Fraction.
Abstract
Background: Dietary interventions in heart failure (HF) remain limited, with current guidance focused largely on sodium restriction. Ketone metabolism has emerged as a potential therapeutic target in HF, with ketone supplementation shown to improve cardiac function. However, there are currently no studies investigating factors affecting adherence to a ketogenic diet (KD) in HF. Aim: To explore the factors influencing adherence to a KD in patients with HF to inform future dietary interventions. Method: This qualitative study was embedded within the KETO-HF pilot randomised controlled trial, in which participants with HF with reduced ejection fraction undertook a 4-month KD. Consenting participants were invited to complete semi-structured interviews. Interviews were audio-recorded, deidentified and transcribed verbatim. Data were analysed using thematic analysis with a mixed inductive-deductive strategy. Results: Fifteen participants were interviewed. Facilitators of adherence were: (1) personal motivation and self-regulation; (2) improved well-being; (3) interpersonal support and; (4) adaptive strategies and improved nutritional literacy. Barriers included: (1) early-phase physiological and psychological challenges; (2) social and cultural friction; (3) competing family and work demands and; (4) limited availability of suitable foods, particularly difficulty managing social situations and dining out. Conclusions: Adherence to a KD in people with HF is shaped by a combination of individual and social factors. These findings highlight the need for improved education, support, and increased food options to optimise implementation of dietary ketosis in HF.
Clinical relevance
In patients with HFrEF (LVEF ≤40%) undergoing a 4-month ketogenic diet intervention within a pilot RCT, what individual, interpersonal, and contextual factors facilitate or impede dietary adherence, and how can these findings inform the design of future dietary ketosis trials in heart failure? __SNAPSHOT__ {"studyDesign":"Qualitative sub-study (semi-structured interviews with thematic analysis using a mixed inductive-deductive strategy) embedded within the KETO-HF open-label, prospective pilot randomised controlled trial","setting":"Western Sydney Local Health District, Australia (university-affiliated tertiary cardiac care setting; ethics approval 2023_ETH00989); interviews conducted in-person or via Zoom between January 2025 and May 2026","sampleSize":"n=15 (representing 50% of the KETO-HF pilot RCT intervention arm); 2 of 15 did not complete the full 4-month trial but their data were retained","population":"Adults aged ≥18 years with confirmed HFrEF (LVEF ≤40%), English-speaking, randomised to the ketogenic diet intervention arm of the KETO-HF pilot RCT; purposive sampling targeting information-rich cases","intervention":"Normocaloric ketogenic diet (KD) for 4 months, targeting 20–30 g/day carbohydrate (<5–10% daily energy), 70% energy from healthy fat, 20% from protein; initiated with one-on-one dietitian consultation and supported by food diary and/or smartphone app for carbohydrate tracking and urine ketone self-monitoring","comparator":"Not applicable (this qualitative sub-study examined only the intervention arm; the parent KETO-HF RCT includes a no-dietary-intervention control arm with planned total n=60)","primaryOutcome":"Thematic identification of facilitators and barriers to adherence to a ketogenic diet in patients with HFrEF; no quantitative primary endpoint defined","followUp":"4 months (interviews conducted at the final follow-up visit of the intervention period)","fundingSource":"Investigator-initiated; specific funding source not reported in the abstract or MDPI publication page"}
Key findings
Fifteen participants were interviewed; data saturation was reported to have been reached by participant 10, with continuation to 15 to ensure depth and diversity of perspectives. Thematic analysis identified four facilitators of adherence: (1) personal motivation and self-regulation; (2) improved subjective well-being; (3) interpersonal support; and (4) adaptive strategies and improved nutritional literacy. Four corresponding barriers were identified: (1) early-phase physiological and psychological challenges (consistent with the 'keto-flu' phenomenon described in the broader literature); (2) social and cultural friction; (3) competing family and work demands; and (4) limited availability of suitable foods, particularly difficulty managing social situations and dining out. No quantitative adherence rates, p-values, confidence intervals, or effect sizes are reported in this qualitative study, as none are applicable to the design. The proportion of participants who completed versus discontinued the intervention is noted (2/15 did not complete), but formal non-completion rates for the parent trial cohort are not yet reported.
Practice implications
This study establishes, for the first time in HFrEF populations, a structured qualitative account of the determinants of ketogenic diet adherence — a domain previously unexamined in this patient group. The findings are hypothesis-generating and implementation-informing rather than practice-validating: they do not establish whether a ketogenic diet improves HFrEF outcomes, nor do they quantify adherence rates or their relationship to clinical endpoints. The results apply specifically to English-speaking, ambulatory HFrEF patients (LVEF ≤40%) who were motivated enough to enroll in and consent to a dietary RCT — a population likely skewed toward higher baseline motivation compared with typical HFrEF clinic attendees. Patients with advanced HF, significant frailty, cognitive impairment, non-English language preference, or complex polypharmacy were not adequately represented. The identified barriers — particularly early physiological challenges, social friction, and food environment constraints — have direct implications for how future KD trials should be structured (e.g., intensified early-phase dietitian support, social facilitation strategies, and attention to culturally appropriate food options). The facilitators — especially interpersonal support and growing nutritional literacy — suggest modifiable targets for intervention design. Clinicians should note that only the abstract was publicly available at time of search; the full thematic framework, illustrative quotes, and any participant demographic breakdown are contained in the full article and its supplementary materials, which limits independent appraisal of analytical rigour. __LIMITATIONS__ Very small sample size (n=15 from a single intervention arm of a pilot RCT), limiting transferability of themes to broader HFrEF populations or different healthcare systems.,Single-site, single-country study (Australia) with English-language requirement, substantially restricting generalisability across ethnic, linguistic, cultural, and socioeconomic groups.,Purposive sampling from a volunteer RCT population introduces significant selection bias toward patients already motivated to attempt dietary change — the most challenging-to-reach patients are structurally excluded.,Qualitative design by nature cannot quantify the magnitude or relative importance of individual barriers and facilitators, nor can it establish causal relationships between adherence determinants and clinical outcomes.,The parent KETO-HF RCT remains ongoing (target n=60); clinical efficacy and safety data for the KD in HFrEF are not yet available from this programme, and it would be premature to extrapolate adherence facilitators to effectiveness.,Interviewer was the study's first author, raising potential for social desirability bias despite use of deidentification procedures; the absence of prior participant relationships is noted but does not eliminate this risk.,Two participants did not complete the trial, which may have introduced informative missingness; although their data were retained, views of those who declined to participate in the sub-study (50% of the intervention arm) are unknown.,No validated quantitative adherence metric (e.g., blood or urinary ketone levels correlated with self-report) is described as an anchor for the qualitative themes, limiting triangulation of findings.,Funding source is not reported, precluding assessment of potential sponsorship-related bias. __BOTTOM_LINE_CATEGORY__ promising_but_preliminary __BOTTOM_LINE__ This first-of-its-kind qualitative study in HFrEF patients identifies actionable facilitators (personal motivation, social support, nutritional literacy) and tractable barriers (early physiological symptoms, social and food environment constraints) to ketogenic diet adherence — findings that should directly inform the design of support structures in future KD trials in this population. The study does not establish clinical efficacy or safety of the ketogenic diet in HFrEF, and findings should not be used to recommend or initiate ketogenic diets in clinical practice outside of a research context. Future adequately powered trials with objective adherence monitoring and diverse patient populations are required before any practice change is warranted.