{"id":94653,"date":"2026-10-21T08:28:44","date_gmt":"2026-10-21T08:28:44","guid":{"rendered":"https:\/\/betterme.world\/articles\/?p=94653"},"modified":"2026-10-21T08:28:44","modified_gmt":"2026-10-21T08:28:44","slug":"84-hour-water-fast","status":"publish","type":"post","link":"https:\/\/betterme.world\/articles\/84-hour-water-fast\/","title":{"rendered":"84-hour water fast: research, risks, and limitations"},"content":{"rendered":"<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_75 counter-hierarchy ez-toc-counter ez-toc-grey ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<span class=\"ez-toc-title-toggle\"><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/betterme.world\/articles\/84-hour-water-fast\/#Key_takeaways\" >Key takeaways<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/betterme.world\/articles\/84-hour-water-fast\/#What_is_an_84-hour_fast\" >What is an 84-hour fast?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/betterme.world\/articles\/84-hour-water-fast\/#What_are_the_side_effects_of_an_84-hour_water_fast\" >What are the side effects of an 84-hour water fast?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/betterme.world\/articles\/84-hour-water-fast\/#What_happens_when_you_fast_for_84_hours\" >What happens when you fast for 84 hours?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/betterme.world\/articles\/84-hour-water-fast\/#What_does_research_say_about_84-hour_fasting_benefits\" >What does research say about 84-hour fasting benefits?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/betterme.world\/articles\/84-hour-water-fast\/#What_are_the_risks_of_an_84-hour_water_fast\" >What are the risks of an 84-hour water fast?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/betterme.world\/articles\/84-hour-water-fast\/#What_should_you_discuss_before_an_84-hour_water_fast\" >What should you discuss before an 84-hour water fast?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"https:\/\/betterme.world\/articles\/84-hour-water-fast\/#How_should_you_approach_eating_after_an_84-hour_fast\" >How should you approach eating after an 84-hour fast?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-9\" href=\"https:\/\/betterme.world\/articles\/84-hour-water-fast\/#Who_should_avoid_the_84-hour_water_fast\" >Who should avoid the 84-hour water fast?<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-10\" href=\"https:\/\/betterme.world\/articles\/84-hour-water-fast\/#Which_symptoms_mean_you_should_stop_fasting\" >Which symptoms mean you should stop fasting?<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-11\" href=\"https:\/\/betterme.world\/articles\/84-hour-water-fast\/#How_often_can_you_do_an_84-hour_water_fast\" >How often can you do an 84-hour water fast?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-12\" href=\"https:\/\/betterme.world\/articles\/84-hour-water-fast\/#What_results_can_you_get_from_an_84-hour_water_fast\" >What results can you get from an 84-hour water fast?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-13\" href=\"https:\/\/betterme.world\/articles\/84-hour-water-fast\/#FAQs\" >FAQs<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-14\" href=\"https:\/\/betterme.world\/articles\/84-hour-water-fast\/#What_can_break_an_84-hour_water_fast\" >What can break an 84-hour water fast?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-15\" href=\"https:\/\/betterme.world\/articles\/84-hour-water-fast\/#Does_the_84-hour_water_fast_boost_fat_loss\" >Does the 84-hour water fast boost fat loss?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-16\" href=\"https:\/\/betterme.world\/articles\/84-hour-water-fast\/#Can_you_work_out_during_an_84-hour_water_fast\" >Can you work out during an 84-hour water fast?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-17\" href=\"https:\/\/betterme.world\/articles\/84-hour-water-fast\/#Can_the_84-hour_water_fast_improve_mental_clarity\" >Can the 84-hour water fast improve mental clarity?<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-18\" href=\"https:\/\/betterme.world\/articles\/84-hour-water-fast\/#The_bottom_line\" >The bottom line<\/a><\/li><\/ul><\/nav><\/div>\n<p><span style=\"font-weight: 400;\">An 84-hour water fast means drinking only water for three and a half days. Prolonged food restriction carries risks that depend on medical conditions, medications, and nutritional status. Our guide to <\/span><a href=\"https:\/\/betterme.world\/articles\/fasting-for-3-days\/\"><span style=\"font-weight: 400;\">fasting for 3 days<\/span><\/a><span style=\"font-weight: 400;\"> explains the related 72-hour approach.<\/span><\/p>\n<p><span data-sheets-root=\"1\"><a href=\"https:\/\/quiz.betterme.world\/first-page-generated-gender?flow=2273&amp;utm_source=Blog&amp;utm_medium=Blog&amp;utm_campaign=84_hour_water_fast\" target=\"_blank\"><video autoplay=\"autoplay\" loop=\"loop\" muted=\"muted\" playsinline=\"playsinline\" width=\"777\"><source src=\"https:\/\/cdn.betterme.world\/articles\/wp-content\/uploads\/2021\/02\/ezgif.com-gif-to-mp4.mp4\" type=\"video\/mp4\" \/><\/video><\/a><\/span><\/p>\n<p><span style=\"font-weight: 400;\">Every fast is a personal experience. Your dietary preferences, body composition, and activity level all influence your fasting journey. It&#8217;s advisable to consult with a healthcare provider before embarking on a fasting regimen.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Following exercise and diet plans is the key in your fitness journey and greatly impacts results. In 4 weeks users can typically expect to lose not more than 1-2 lbs per week. Individual results may vary.<\/span><\/p>\n<h2 style=\"text-align: center;\"><span class=\"ez-toc-section\" id=\"Key_takeaways\"><\/span><b>Key takeaways<\/b><span class=\"ez-toc-section-end\"><\/span><\/h2>\n<ul>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">An 84-hour water fast means consuming only water for three and a half days.<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">Studies of prolonged fasting report adverse effects as well as changes in metabolic measurements (<\/span><a href=\"https:\/\/pmc.ncbi.nlm.nih.gov\/articles\/PMC11494232\/\"><span style=\"font-weight: 400;\">1<\/span><\/a><span style=\"font-weight: 400;\">).<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">Pregnancy, breastfeeding, and an eating-disorder history are reasons to avoid fasting (<\/span><a href=\"https:\/\/www.hopkinsmedicine.org\/health\/expert-qa\/intermittent-fasting-what-is-it-and-how-does-it-work\"><span style=\"font-weight: 400;\">2<\/span><\/a><span style=\"font-weight: 400;\">).<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">Diabetes medication can change the risks of missing meals; dose changes need clinical guidance (<\/span><a href=\"https:\/\/www.niddk.nih.gov\/health-information\/professionals\/diabetes-discoveries-practice\/fasting-safely-with-diabetes\"><span style=\"font-weight: 400;\">3<\/span><\/a><span style=\"font-weight: 400;\">).<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">Refeeding risk depends on nutritional status and other factors, not only the length of the fast (<\/span><a href=\"https:\/\/www.nice.org.uk\/guidance\/cg32\/chapter\/Recommendations\"><span style=\"font-weight: 400;\">4<\/span><\/a><span style=\"font-weight: 400;\">).<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">Changes in scale weight during prolonged fasting include changes beyond body fat (<\/span><a href=\"https:\/\/pmc.ncbi.nlm.nih.gov\/articles\/PMC11494232\/\"><span style=\"font-weight: 400;\">1<\/span><\/a><span style=\"font-weight: 400;\">).<\/span><\/li>\n<\/ul>\n<p><img decoding=\"async\" src=\"https:\/\/cdn.betterme.world\/articles\/wp-content\/uploads\/2025\/11\/How-To-Get-Rid-Of-Water-Retention-Overnight_-Beat-Bloat-With-These-Tips.png\" \/><\/p>\n<h2 style=\"text-align: center;\"><span class=\"ez-toc-section\" id=\"What_is_an_84-hour_fast\"><\/span><b>What is an 84-hour fast?<\/b><span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p><span style=\"font-weight: 400;\">An 84-hour water fast excludes food and drinks other than water. Coffee, tea, flavored water, and broth belong to other fasting protocols.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Extending a fast from 72 to 84 hours adds another half-day without food. Longer fasting periods can carry risks and need clinical assessment (<\/span><a href=\"https:\/\/www.hopkinsmedicine.org\/health\/expert-qa\/intermittent-fasting-what-is-it-and-how-does-it-work\"><span style=\"font-weight: 400;\">2<\/span><\/a><span style=\"font-weight: 400;\">).<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Water fasting for a week involves a longer period without food. Duration and medical supervision are important when interpreting fasting research.<\/span><\/p>\n<p><em><strong>Read more:<\/strong> <a href=\"https:\/\/betterme.world\/articles\/is-a-13-hour-fast-effective\/\">Is a 13-hour fast effective?<\/a><\/em><\/p>\n<h2 style=\"text-align: center;\"><span class=\"ez-toc-section\" id=\"What_are_the_side_effects_of_an_84-hour_water_fast\"><\/span><b>What are the side effects of an 84-hour water fast?<\/b><span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p><span style=\"font-weight: 400;\">Prolonged water fasting can cause adverse effects. Individual risk depends on factors such as medical conditions, medications, and nutritional status (<\/span><a href=\"https:\/\/pmc.ncbi.nlm.nih.gov\/articles\/PMC11494232\/\"><span style=\"font-weight: 400;\">1<\/span><\/a><span style=\"font-weight: 400;\">).<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Human prolonged-fasting studies have reported symptoms including (<\/span><a href=\"https:\/\/pmc.ncbi.nlm.nih.gov\/articles\/PMC11494232\/\"><span style=\"font-weight: 400;\">1<\/span><\/a><span style=\"font-weight: 400;\">):<\/span><\/p>\n<ul>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">Hunger<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">Headache<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">Fatigue<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">Dry mouth or difficulty sleeping<\/span><\/li>\n<\/ul>\n<p><span style=\"font-weight: 400;\">Symptoms should not be dismissed as evidence that a fast is working. Ask a clinician about the risks before starting, and stop if you become unwell.<\/span><\/p>\n<p><img decoding=\"async\" src=\"https:\/\/cdn.betterme.world\/articles\/wp-content\/uploads\/2025\/07\/mental-sad.png\" \/><\/p>\n<h2 style=\"text-align: center;\"><span class=\"ez-toc-section\" id=\"What_happens_when_you_fast_for_84_hours\"><\/span><b>What happens when you fast for 84 hours?<\/b><span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p><span style=\"font-weight: 400;\">During fasting, the body draws on stored energy and ketone production can rise. These processes overlap and vary between people (<\/span><a href=\"https:\/\/pmc.ncbi.nlm.nih.gov\/articles\/PMC11494232\/\"><span style=\"font-weight: 400;\">1<\/span><\/a><span style=\"font-weight: 400;\">).<\/span><\/p>\n\t\t\t\t\t\t<div class=\"wpsm-comptable-wrap\">\n\t\t\t\t<table id=\"wpsm-table-1730\" class=\"wpsm-comptable \">\n\t\t\t\t\t\t\t\t\t<thead class=\"wpsm-thead wpsm-thead-default\">\n\t\t\t\t\t\t<tr>\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<th>Topic<\/th>\n\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<th>What the research can tell us<\/th>\n\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t<\/tr>\n\t\t\t\t\t<\/thead>\n\t\t\t\t\t<tbody class=\"wpsm-tbody\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<tr>\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<td>\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\tStored energy and ketones\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/td>\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<td>\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\tThe body draws on stored energy and ketone production can rise; timing varies (1).\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/td>\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/tr>\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<tr>\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<td>\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\tStudy setting\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/td>\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<td>\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\tA small study followed 13 volunteers through a medically supervised 21-day fast (5).\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/td>\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/tr>\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<tr>\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<td>\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\tScale weight\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/td>\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<td>\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\tChanges during prolonged fasting can include fat, lean tissue, and body water (1).\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/td>\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/tr>\n\t\t\t\t\t\t\t\t\t\t<\/tbody>\n\t\t\t\t<\/table>\n\t\t\t<\/div>\n\t\t\n<p><span style=\"font-weight: 400;\">Our <\/span><a href=\"https:\/\/betterme.world\/articles\/water-fasting-stages\/\"><span style=\"font-weight: 400;\">water-fasting stages guide<\/span><\/a><span style=\"font-weight: 400;\"> explains the terminology used to describe changes in energy use.<\/span><\/p>\n<h2 style=\"text-align: center;\"><span class=\"ez-toc-section\" id=\"What_does_research_say_about_84-hour_fasting_benefits\"><\/span><b>What does research say about 84-hour fasting benefits?<\/b><span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p><span style=\"font-weight: 400;\">A review of human trials found changes in weight, blood pressure, and some metabolic measurements during prolonged fasting. Effects varied across markers, and follow-up raised questions about how long changes lasted (<\/span><a href=\"https:\/\/pmc.ncbi.nlm.nih.gov\/articles\/PMC11494232\/\"><span style=\"font-weight: 400;\">1<\/span><\/a><span style=\"font-weight: 400;\">).<\/span><\/p>\n<ul>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">Studies use different durations and levels of supervision. The 21-day study described in the table does not predict the outcome of an 84-hour fast at home (<\/span><a href=\"https:\/\/www.nature.com\/articles\/s41598-024-80049-2\"><span style=\"font-weight: 400;\">5<\/span><\/a><span style=\"font-weight: 400;\">).<\/span><\/li>\n<\/ul>\n<p><span style=\"font-weight: 400;\">The studies discussed here do not establish an 84-hour timetable for immune changes, cellular repair, or clearer thinking.<\/span><\/p>\n<p><img decoding=\"async\" src=\"https:\/\/cdn.betterme.world\/articles\/wp-content\/uploads\/2025\/07\/senior-man.png\" \/><\/p>\n<h2 style=\"text-align: center;\"><span class=\"ez-toc-section\" id=\"What_are_the_risks_of_an_84-hour_water_fast\"><\/span><b>What are the risks of an 84-hour water fast?<\/b><span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p><span style=\"font-weight: 400;\">Risks deserve attention before any decision about prolonged fasting. The following concerns depend on the person&#8217;s circumstances:<\/span><\/p>\n<ul>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><b>Fluid and electrolyte problems:<\/b><span style=\"font-weight: 400;\"> prolonged restriction can require clinical monitoring of hydration and blood chemistry (<\/span><a href=\"https:\/\/pmc.ncbi.nlm.nih.gov\/articles\/PMC11494232\/\"><span style=\"font-weight: 400;\">1<\/span><\/a><span style=\"font-weight: 400;\">).<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\"><strong>Dehydration:<\/strong> some diabetes medicines and diuretics can increase fluid loss during fasting (<\/span><a href=\"https:\/\/www.niddk.nih.gov\/health-information\/professionals\/diabetes-discoveries-practice\/fasting-safely-with-diabetes\"><span style=\"font-weight: 400;\">3<\/span><\/a><span style=\"font-weight: 400;\">).<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><b>Low blood sugar:<\/b><span style=\"font-weight: 400;\"> fasting can be particularly risky for people taking insulin or certain other diabetes medicines. Medication changes require the prescribing clinician&#8217;s advice (<\/span><a href=\"https:\/\/www.niddk.nih.gov\/health-information\/professionals\/diabetes-discoveries-practice\/fasting-safely-with-diabetes\"><span style=\"font-weight: 400;\">3<\/span><\/a><span style=\"font-weight: 400;\">).<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><b>Lean-tissue loss:<\/b><span style=\"font-weight: 400;\"> studies of prolonged fasting have measured reductions in lean mass as well as fat mass. Lean-mass measurements also reflect changes in body water (<\/span><a href=\"https:\/\/pmc.ncbi.nlm.nih.gov\/articles\/PMC11494232\/\"><span style=\"font-weight: 400;\">1<\/span><\/a><span style=\"font-weight: 400;\">).<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><b>Refeeding problems:<\/b><span style=\"font-weight: 400;\"> people who are malnourished or have other risk factors may need monitored nutrition support when food is reintroduced (<\/span><a href=\"https:\/\/www.nice.org.uk\/guidance\/cg32\/chapter\/Recommendations\"><span style=\"font-weight: 400;\">4<\/span><\/a><span style=\"font-weight: 400;\">).<\/span><\/li>\n<\/ul>\n<p><strong>BetterMe: Health Coaching app can help you build a more structured approach to your wellness routine with meal plans, workouts, and habit-tracking tools. <a href=\"https:\/\/quiz.betterme.world\/first-page-generated-gender?flow=2273&amp;utm_source=Blog&amp;utm_medium=Blog&amp;utm_campaign=84_hour_water_fast\">Start using the app<\/a> to explore options that may support your personal fitness and nutrition goals.<\/strong><\/p>\n<h2 style=\"text-align: center;\"><span class=\"ez-toc-section\" id=\"What_should_you_discuss_before_an_84-hour_water_fast\"><\/span><b>What should you discuss before an 84-hour water fast?<\/b><span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p><span style=\"font-weight: 400;\">Discuss your medical history, current food intake, and medication list with a qualified clinician before considering prolonged fasting. Do not use shorter fasts as a self-directed progression toward 84 hours.<\/span><\/p>\n<ol>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">Ask whether prolonged food restriction is appropriate for your circumstances.<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">Ask how your medications interact with missed meals; do not change doses yourself (<\/span><a href=\"https:\/\/www.niddk.nih.gov\/health-information\/professionals\/diabetes-discoveries-practice\/fasting-safely-with-diabetes\"><span style=\"font-weight: 400;\">3<\/span><\/a><span style=\"font-weight: 400;\">).<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">Discuss hydration and nutritional status, including any recent unintentional weight loss (<\/span><a href=\"https:\/\/www.nice.org.uk\/guidance\/cg32\/chapter\/Recommendations\"><span style=\"font-weight: 400;\">4<\/span><\/a><span style=\"font-weight: 400;\">).<\/span><\/li>\n<\/ol>\n<p><span style=\"font-weight: 400;\">Ask what symptoms require stopping and how eating should resume. A general online preparation plan cannot replace that assessment.<\/span><\/p>\n<p><img decoding=\"async\" src=\"https:\/\/cdn.betterme.world\/articles\/wp-content\/uploads\/2025\/07\/walking-1.png\" \/><\/p>\n<h2 style=\"text-align: center;\"><span class=\"ez-toc-section\" id=\"How_should_you_approach_eating_after_an_84-hour_fast\"><\/span><b>How should you approach eating after an 84-hour fast?<\/b><span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p><span style=\"font-weight: 400;\">Discuss reintroducing food with a clinician, especially if you were eating poorly before the fast or have lost weight unintentionally.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Clinical guidance assesses refeeding risk using nutritional status, previous food intake, blood electrolyte levels, and other factors. The duration of this fast alone cannot determine an individual&#8217;s risk (<\/span><a href=\"https:\/\/www.nice.org.uk\/guidance\/cg32\/chapter\/Recommendations\"><span style=\"font-weight: 400;\">4<\/span><\/a><span style=\"font-weight: 400;\">).<\/span><\/p>\n<p><span style=\"font-weight: 400;\">People at high risk need care from professionals experienced in nutrition support (<\/span><a href=\"https:\/\/www.nice.org.uk\/guidance\/cg32\/chapter\/Recommendations\"><span style=\"font-weight: 400;\">4<\/span><\/a><span style=\"font-weight: 400;\">).<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Our article on <\/span><a href=\"https:\/\/betterme.world\/articles\/what-to-eat-after-a-water-fast\/\"><span style=\"font-weight: 400;\">what to eat after a water fast<\/span><\/a><span style=\"font-weight: 400;\"> explains general food choices after fasting. Refeeding concerns require individual clinical assessment.<\/span><\/p>\n<h2 style=\"text-align: center;\"><span class=\"ez-toc-section\" id=\"Who_should_avoid_the_84-hour_water_fast\"><\/span><b>Who should avoid the 84-hour water fast?<\/b><span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p><span style=\"font-weight: 400;\">Avoid fasting during pregnancy or breastfeeding or if you have an eating-disorder history (<\/span><a href=\"https:\/\/www.hopkinsmedicine.org\/health\/expert-qa\/intermittent-fasting-what-is-it-and-how-does-it-work\"><span style=\"font-weight: 400;\">2<\/span><\/a><span style=\"font-weight: 400;\">). Being underweight, recent unintentional weight loss, medical conditions, and medication use also warrant individual assessment.<\/span><\/p>\n<ul>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">Pregnancy or breastfeeding<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">A history of eating disorders<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">Underweight or recent unintentional weight loss<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">Diabetes, especially when using insulin or other glucose-lowering medication (<\/span><a href=\"https:\/\/www.niddk.nih.gov\/health-information\/professionals\/diabetes-discoveries-practice\/fasting-safely-with-diabetes\"><span style=\"font-weight: 400;\">3<\/span><\/a><span style=\"font-weight: 400;\">)<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">Kidney, liver, or heart conditions<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">Medication that must be taken with food<\/span><\/li>\n<\/ul>\n<p><em><strong>Read more:<\/strong> <a href=\"https:\/\/betterme.world\/articles\/fasting-while-traveling\/\">Fasting while traveling<\/a><\/em><\/p>\n<h3 style=\"text-align: center;\"><span class=\"ez-toc-section\" id=\"Which_symptoms_mean_you_should_stop_fasting\"><\/span><b>Which symptoms mean you should stop fasting?<\/b><span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p><span style=\"font-weight: 400;\">Stop fasting and seek urgent medical help for the following symptoms. Do not wait for the planned end time:<\/span><\/p>\n<ul>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">Chest pain<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">Fainting or near-fainting<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">Severe confusion<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">A sustained irregular heartbeat<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">Extreme weakness<\/span><\/li>\n<\/ul>\n<p><img decoding=\"async\" src=\"https:\/\/cdn.betterme.world\/articles\/wp-content\/uploads\/2025\/05\/Banner-mental-health1.png\" \/><\/p>\n<h2 style=\"text-align: center;\"><span class=\"ez-toc-section\" id=\"How_often_can_you_do_an_84-hour_water_fast\"><\/span><b>How often can you do an 84-hour water fast?<\/b><span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p><span style=\"font-weight: 400;\">Discuss whether prolonged fasting is appropriate with a clinician before considering another fast. Your medical history and nutritional status matter when making that decision.<\/span><\/p>\n<h2 style=\"text-align: center;\"><span class=\"ez-toc-section\" id=\"What_results_can_you_get_from_an_84-hour_water_fast\"><\/span><b>What results can you get from an 84-hour water fast?<\/b><span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p><span style=\"font-weight: 400;\">A lower scale reading during fasting can include changes in body water and lean mass as well as fat. It should not be read as an equivalent amount of lasting fat loss (<\/span><a href=\"https:\/\/pmc.ncbi.nlm.nih.gov\/articles\/PMC11494232\/\"><span style=\"font-weight: 400;\">1<\/span><\/a><span style=\"font-weight: 400;\">).<\/span><\/p>\n<p><span style=\"font-weight: 400;\">The review found limited follow-up and that several metabolic changes were not maintained after people resumed eating. A single fast is not a reliable way to predict long-term results (<\/span><a href=\"https:\/\/pmc.ncbi.nlm.nih.gov\/articles\/PMC11494232\/\"><span style=\"font-weight: 400;\">1<\/span><\/a><span style=\"font-weight: 400;\">).<\/span><\/p>\n<p><strong>Whether you\u2019re just starting your fitness journey or looking to add more structure to your routine, BetterMe offers tools that can support different wellness goals. <a href=\"https:\/\/quiz.betterme.world\/first-page-generated-gender?flow=2273&amp;utm_source=Blog&amp;utm_medium=Blog&amp;utm_campaign=84_hour_water_fast\">Explore the app<\/a> and see how its workout, nutrition, and habit-building features can fit into your lifestyle.<\/strong><\/p>\n<p><img decoding=\"async\" src=\"https:\/\/cdn.betterme.world\/articles\/wp-content\/uploads\/2025\/06\/Overlay-Banner-GYM-workouts-for-young-men-4.png\" \/><\/p>\n<h2><span class=\"ez-toc-section\" id=\"FAQs\"><\/span><b>FAQs<\/b><span class=\"ez-toc-section-end\"><\/span><\/h2><ul><li><h3><span class=\"ez-toc-section\" id=\"What_can_break_an_84-hour_water_fast\"><\/span><strong>What can break an 84-hour water fast?<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3><\/li><\/ul><p><span style=\"font-weight: 400;\">Food or drinks other than water fall outside the water-only definition used here. Some other fasting schedules allow noncaloric drinks, but they are different protocols.<\/span><\/p>\n<ul><li><h3><span class=\"ez-toc-section\" id=\"Does_the_84-hour_water_fast_boost_fat_loss\"><\/span><strong>Does the 84-hour water fast boost fat loss?<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3><\/li><\/ul><p><span style=\"font-weight: 400;\">Scale changes during prolonged fasting include changes in body water and lean mass as well as fat (<\/span><a href=\"https:\/\/pmc.ncbi.nlm.nih.gov\/articles\/PMC11494232\/\"><span style=\"font-weight: 400;\">1<\/span><\/a><span style=\"font-weight: 400;\">). This makes short-term weight loss an unreliable measure of sustained fat loss.<\/span><\/p>\n<ul><li><h3><span class=\"ez-toc-section\" id=\"Can_you_work_out_during_an_84-hour_water_fast\"><\/span><strong>Can you work out during an 84-hour water fast?<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3><\/li><\/ul><p><span style=\"font-weight: 400;\">Avoid strenuous exercise during a prolonged fast, and discuss activity with your clinician. Stop activity and seek help if you feel faint, confused, or otherwise unwell.<\/span><\/p>\n<ul><li><h3><span class=\"ez-toc-section\" id=\"Can_the_84-hour_water_fast_improve_mental_clarity\"><\/span><strong>Can the 84-hour water fast improve mental clarity?<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3><\/li><\/ul><p><span style=\"font-weight: 400;\">The research discussed here does not establish clearer thinking as an outcome of an 84-hour water fast. Fatigue and other adverse effects have been reported during prolonged fasting (<\/span><a href=\"https:\/\/pmc.ncbi.nlm.nih.gov\/articles\/PMC11494232\/\"><span style=\"font-weight: 400;\">1<\/span><\/a><span style=\"font-weight: 400;\">).<\/span><\/p>\n\n<p><span data-sheets-root=\"1\"><a href=\"https:\/\/quiz.betterme.world\/first-page-generated-gender?flow=2273&amp;utm_source=Blog&amp;utm_medium=Blog&amp;utm_campaign=84_hour_water_fast\" target=\"_blank\"><video autoplay=\"autoplay\" loop=\"loop\" muted=\"muted\" playsinline=\"playsinline\" width=\"777\"><source src=\"https:\/\/cdn.betterme.world\/articles\/wp-content\/uploads\/2023\/10\/ezgif.com-gif-to-mp4-12.mp4\" type=\"video\/mp4\" \/><\/video><\/a><\/span><\/p>\n<h2 style=\"text-align: left;\"><span class=\"ez-toc-section\" id=\"The_bottom_line\"><\/span><b>The bottom line<\/b><span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p><span style=\"font-weight: 400;\">An 84-hour water fast involves prolonged food restriction with uncertain benefits and possible adverse effects. It is not a reliable shortcut to lasting weight change.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Discuss suitability, medication use, and reintroducing food with a clinician before considering it.<\/span><\/p>\n","protected":false},"excerpt":{"rendered":"<p>An 84-hour water fast means drinking only water for three and a half days. Prolonged food restriction carries risks that depend on medical conditions, medications, and nutritional status. Our guide to fasting for 3 days explains the related 72-hour approach. Every fast is a personal experience. Your dietary preferences, body composition, and activity level all [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":94655,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[150],"tags":[],"coauthors":[45],"class_list":["post-94653","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-fasting-diet"],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO Premium plugin v27.8 (Yoast SEO v27.8) - https:\/\/yoast.com\/product\/yoast-seo-premium-wordpress\/ -->\n<title>84-hour water fast: risks and what to know | BetterMe<\/title>\n<meta name=\"description\" content=\"Thinking about a long fast? Learn the facts on an \u2605 84 HOUR WATER FAST \u27a4 why some people try it, what the risks are, and what to consider before starting.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/betterme.world\/articles\/84-hour-water-fast\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"84-hour water fast: research, risks, and limitations\" \/>\n<meta property=\"og:description\" content=\"Thinking about a long fast? Learn the facts on an \u2605 84 HOUR WATER FAST \u27a4 why some people try it, what the risks are, and what to consider before starting.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/betterme.world\/articles\/84-hour-water-fast\/\" \/>\n<meta property=\"og:site_name\" content=\"BetterMe Blog\" \/>\n<meta property=\"article:publisher\" content=\"https:\/\/www.facebook.com\/betterme.health.coaching\" \/>\n<meta property=\"article:author\" content=\"#\" \/>\n<meta property=\"og:image\" content=\"https:\/\/cdn.betterme.world\/articles\/wp-content\/uploads\/2026\/10\/480-84-hour-water-fast-1024x640.png\" \/>\n\t<meta property=\"og:image:width\" content=\"1024\" \/>\n\t<meta property=\"og:image:height\" content=\"640\" \/>\n\t<meta property=\"og:image:type\" content=\"image\/png\" \/>\n<meta name=\"author\" content=\"BetterMe\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:creator\" content=\"@betterme\" \/>\n<meta name=\"twitter:site\" content=\"@betterme\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"BetterMe\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"7 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\\\/\\\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\\\/\\\/betterme.world\\\/articles\\\/84-hour-water-fast\\\/#article\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/betterme.world\\\/articles\\\/84-hour-water-fast\\\/\"},\"author\":{\"name\":\"BetterMe\",\"@id\":\"https:\\\/\\\/betterme.world\\\/articles\\\/#\\\/schema\\\/person\\\/5ee91a20dad2dd2c5fccf2fec8ccc79d\"},\"headline\":\"84-hour water fast: research, risks, and limitations\",\"mainEntityOfPage\":{\"@id\":\"https:\\\/\\\/betterme.world\\\/articles\\\/84-hour-water-fast\\\/\"},\"wordCount\":1189,\"publisher\":{\"@id\":\"https:\\\/\\\/betterme.world\\\/articles\\\/#organization\"},\"image\":{\"@id\":\"https:\\\/\\\/betterme.world\\\/articles\\\/84-hour-water-fast\\\/#primaryimage\"},\"thumbnailUrl\":\"https:\\\/\\\/cdn.betterme.world\\\/articles\\\/wp-content\\\/uploads\\\/2026\\\/10\\\/480-84-hour-water-fast.png\",\"articleSection\":[\"Fasting\"],\"inLanguage\":\"en-US\",\"articleBody\":\"<span style=\\\"font-weight: 400;\\\">An 84-hour water fast means drinking only water for three and a half days. Prolonged food restriction carries risks that depend on medical conditions, medications, and nutritional status. Our guide to <\\\/span><a href=\\\"https:\\\/\\\/betterme.world\\\/articles\\\/fasting-for-3-days\\\/\\\"><span style=\\\"font-weight: 400;\\\">fasting for 3 days<\\\/span><\\\/a><span style=\\\"font-weight: 400;\\\"> explains the related 72-hour approach.<\\\/span>\\r\\n\\r\\n<span data-sheets-root=\\\"1\\\"><\\\/span>\\r\\n\\r\\n<span style=\\\"font-weight: 400;\\\">Every fast is a personal experience. Your dietary preferences, body composition, and activity level all influence your fasting journey. It's advisable to consult with a healthcare provider before embarking on a fasting regimen.<\\\/span>\\r\\n\\r\\n<span style=\\\"font-weight: 400;\\\">Following exercise and diet plans is the key in your fitness journey and greatly impacts results. In 4 weeks users can typically expect to lose not more than 1-2 lbs per week. Individual results may vary.<\\\/span>\\r\\n<h2 style=\\\"text-align: center;\\\"><b>Key takeaways<\\\/b><\\\/h2>\\r\\n<ul>\\r\\n \\t<li style=\\\"font-weight: 400;\\\" aria-level=\\\"1\\\"><span style=\\\"font-weight: 400;\\\">An 84-hour water fast means consuming only water for three and a half days.<\\\/span><\\\/li>\\r\\n \\t<li style=\\\"font-weight: 400;\\\" aria-level=\\\"1\\\"><span style=\\\"font-weight: 400;\\\">Studies of prolonged fasting report adverse effects as well as changes in metabolic measurements (<\\\/span><a href=\\\"https:\\\/\\\/pmc.ncbi.nlm.nih.gov\\\/articles\\\/PMC11494232\\\/\\\"><span style=\\\"font-weight: 400;\\\">1<\\\/span><\\\/a><span style=\\\"font-weight: 400;\\\">).<\\\/span><\\\/li>\\r\\n \\t<li style=\\\"font-weight: 400;\\\" aria-level=\\\"1\\\"><span style=\\\"font-weight: 400;\\\">Pregnancy, breastfeeding, and an eating-disorder history are reasons to avoid fasting (<\\\/span><a href=\\\"https:\\\/\\\/www.hopkinsmedicine.org\\\/health\\\/expert-qa\\\/intermittent-fasting-what-is-it-and-how-does-it-work\\\"><span style=\\\"font-weight: 400;\\\">2<\\\/span><\\\/a><span style=\\\"font-weight: 400;\\\">).<\\\/span><\\\/li>\\r\\n \\t<li style=\\\"font-weight: 400;\\\" aria-level=\\\"1\\\"><span st ...\"},{\"@type\":\"WebPage\",\"@id\":\"https:\\\/\\\/betterme.world\\\/articles\\\/84-hour-water-fast\\\/\",\"url\":\"https:\\\/\\\/betterme.world\\\/articles\\\/84-hour-water-fast\\\/\",\"name\":\"84-hour water fast: risks and what to know | BetterMe\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/betterme.world\\\/articles\\\/#website\"},\"primaryImageOfPage\":{\"@id\":\"https:\\\/\\\/betterme.world\\\/articles\\\/84-hour-water-fast\\\/#primaryimage\"},\"image\":{\"@id\":\"https:\\\/\\\/betterme.world\\\/articles\\\/84-hour-water-fast\\\/#primaryimage\"},\"thumbnailUrl\":\"https:\\\/\\\/cdn.betterme.world\\\/articles\\\/wp-content\\\/uploads\\\/2026\\\/10\\\/480-84-hour-water-fast.png\",\"description\":\"Thinking about a long fast? 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Learn the facts on an \u2605 84 HOUR WATER FAST \u27a4 why some people try it, what the risks are, and what to consider before starting.","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/betterme.world\/articles\/84-hour-water-fast\/","og_locale":"en_US","og_type":"article","og_title":"84-hour water fast: research, risks, and limitations","og_description":"Thinking about a long fast? Learn the facts on an \u2605 84 HOUR WATER FAST \u27a4 why some people try it, what the risks are, and what to consider before starting.","og_url":"https:\/\/betterme.world\/articles\/84-hour-water-fast\/","og_site_name":"BetterMe Blog","article_publisher":"https:\/\/www.facebook.com\/betterme.health.coaching","article_author":"#","og_image":[{"width":1024,"height":640,"url":"https:\/\/cdn.betterme.world\/articles\/wp-content\/uploads\/2026\/10\/480-84-hour-water-fast-1024x640.png","type":"image\/png"}],"author":"BetterMe","twitter_card":"summary_large_image","twitter_creator":"@betterme","twitter_site":"@betterme","twitter_misc":{"Written by":"BetterMe","Est. reading time":"7 minutes"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"Article","@id":"https:\/\/betterme.world\/articles\/84-hour-water-fast\/#article","isPartOf":{"@id":"https:\/\/betterme.world\/articles\/84-hour-water-fast\/"},"author":{"name":"BetterMe","@id":"https:\/\/betterme.world\/articles\/#\/schema\/person\/5ee91a20dad2dd2c5fccf2fec8ccc79d"},"headline":"84-hour water fast: research, risks, and limitations","mainEntityOfPage":{"@id":"https:\/\/betterme.world\/articles\/84-hour-water-fast\/"},"wordCount":1189,"publisher":{"@id":"https:\/\/betterme.world\/articles\/#organization"},"image":{"@id":"https:\/\/betterme.world\/articles\/84-hour-water-fast\/#primaryimage"},"thumbnailUrl":"https:\/\/cdn.betterme.world\/articles\/wp-content\/uploads\/2026\/10\/480-84-hour-water-fast.png","articleSection":["Fasting"],"inLanguage":"en-US","articleBody":"<span style=\"font-weight: 400;\">An 84-hour water fast means drinking only water for three and a half days. Prolonged food restriction carries risks that depend on medical conditions, medications, and nutritional status. Our guide to <\/span><a href=\"https:\/\/betterme.world\/articles\/fasting-for-3-days\/\"><span style=\"font-weight: 400;\">fasting for 3 days<\/span><\/a><span style=\"font-weight: 400;\"> explains the related 72-hour approach.<\/span>\r\n\r\n<span data-sheets-root=\"1\"><\/span>\r\n\r\n<span style=\"font-weight: 400;\">Every fast is a personal experience. Your dietary preferences, body composition, and activity level all influence your fasting journey. It's advisable to consult with a healthcare provider before embarking on a fasting regimen.<\/span>\r\n\r\n<span style=\"font-weight: 400;\">Following exercise and diet plans is the key in your fitness journey and greatly impacts results. In 4 weeks users can typically expect to lose not more than 1-2 lbs per week. Individual results may vary.<\/span>\r\n<h2 style=\"text-align: center;\"><b>Key takeaways<\/b><\/h2>\r\n<ul>\r\n \t<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">An 84-hour water fast means consuming only water for three and a half days.<\/span><\/li>\r\n \t<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">Studies of prolonged fasting report adverse effects as well as changes in metabolic measurements (<\/span><a href=\"https:\/\/pmc.ncbi.nlm.nih.gov\/articles\/PMC11494232\/\"><span style=\"font-weight: 400;\">1<\/span><\/a><span style=\"font-weight: 400;\">).<\/span><\/li>\r\n \t<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">Pregnancy, breastfeeding, and an eating-disorder history are reasons to avoid fasting (<\/span><a href=\"https:\/\/www.hopkinsmedicine.org\/health\/expert-qa\/intermittent-fasting-what-is-it-and-how-does-it-work\"><span style=\"font-weight: 400;\">2<\/span><\/a><span style=\"font-weight: 400;\">).<\/span><\/li>\r\n \t<li style=\"font-weight: 400;\" aria-level=\"1\"><span st ..."},{"@type":"WebPage","@id":"https:\/\/betterme.world\/articles\/84-hour-water-fast\/","url":"https:\/\/betterme.world\/articles\/84-hour-water-fast\/","name":"84-hour water fast: risks and what to know | BetterMe","isPartOf":{"@id":"https:\/\/betterme.world\/articles\/#website"},"primaryImageOfPage":{"@id":"https:\/\/betterme.world\/articles\/84-hour-water-fast\/#primaryimage"},"image":{"@id":"https:\/\/betterme.world\/articles\/84-hour-water-fast\/#primaryimage"},"thumbnailUrl":"https:\/\/cdn.betterme.world\/articles\/wp-content\/uploads\/2026\/10\/480-84-hour-water-fast.png","description":"Thinking about a long fast? 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