Religious fasting can change metabolism in older adults, but effects vary by fasting type, duration, individual health, and how fasting is practiced alongside medications and nutrition. Multiple studies report fasting lowers blood glucose and insulin, increases fat use and ketones, and can stimulate cellular repair processes such as autophagy; however, older people may also face risks including muscle loss, low blood pressure, hypoglycemia, nutrient shortfalls, and interactions with chronic-disease treatments, so medical supervision and individualized planning are important[2][1][5].
Why fasting alters metabolism
– During fasting the body shifts from burning recent dietary glucose to mobilizing stored glycogen and then fat, which lowers insulin and raises glucagon and ketone production[2].
– This shift reduces circulating glucose, insulin, and IGF-1 and activates stress-response pathways such as AMPK and reduced mTOR signaling, changes linked to increased cellular maintenance (autophagy) and improved metabolic flexibility[2][1].
Evidence of potential benefits in older adults
– Short-term fasting or fasting-mimicking diets have been associated with improved insulin sensitivity, lower fasting glucose, reduced body weight, and increased markers of autophagy in human trials and translational research[1][2].
– Intermittent fasting patterns (for example time-restricted feeding or periodic fasting) can improve metabolic markers in adults and are generally more sustainable than continuous caloric restriction in some studies[2][3].
Risks and special considerations for elderly people
– Older adults are more vulnerable to losing lean mass during calorie restriction or prolonged fasting; reduced muscle mass worsens strength and metabolic health, so preserving protein intake and activity is crucial[5].
– Fasting can cause low blood sugar, dizziness, low blood pressure, dehydration, or interfere with medications for diabetes, hypertension, or heart disease; these risks are higher in older adults with multiple chronic conditions[5].
– Nutrient deficiencies are a concern if fasting leads to inadequate daily intake of protein, vitamins (for example B12, D), calcium, or other micronutrients already at risk in older populations.
Practical guidance for older adults who choose to fast for religious reasons
– Discuss plans with a healthcare provider before starting; review medications that may need dose changes (especially insulin or sulfonylureas) and confirm monitoring strategies[5].
– Prefer shorter fasting windows or intermittent schedules rather than prolonged fasts, and avoid consecutive extended fasts unless medically supervised[2].
– Prioritize adequate protein and micronutrients during non-fasting periods to protect muscle and bone health; consider resistance exercise to preserve lean mass[5].
– Stay hydrated, break fasts gradually if fasting has been prolonged, and watch for warning symptoms such as fainting, palpitations, confusion, or hypoglycemia.
– If medically advised against fasting, explore alternatives that respect religious intent, such as modified fasts, partial fasting, or approved exemptions under many faith traditions.
How to balance spiritual goals with metabolic health
– Coordinate with religious leaders and clinicians to find acceptable adaptations (for example adjusted times, supervised partial fasts, or medical exemptions) so spiritual practice does not compromise health.
– Use fasting periods as an opportunity to focus on nutrient-dense meals, regular light activity, and sleep, which all support metabolism and resilience during fasting.
Limitations in the evidence
– Many clinical studies are small, short-term, or conducted in younger or mixed-age groups, so direct high-quality evidence specifically in older populations remains limited and more long-term, controlled trials are needed to define optimal fasting strategies for elderly people[2][1].
Sources
https://pmc.ncbi.nlm.nih.gov/articles/PMC12675562/
https://www.prnewswire.com/news-releases/first-ever-human-trial-finds-fasting-mimicking-diet-enhances-autophagy-while-improving-metabolic-health-302643077.html
https://pmc.ncbi.nlm.nih.gov/articles/PMC12734391/
https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2025.1718105/full
https://economictimes.com/magazines/panache/fasting-is-not-a-miracle-cure-apollo-neurologist-busts-popular-myths-revealing-what-it-really-does-for-your-health/articleshow/126058271.cms
