by Nils Osmar and Claude

• © Nils Osmar 2025. November 1, 2025
• This post is not intended as, and should not be taken as, medical advice. 
• See full Medical Disclaimer
• This article was a collaboration between a human and an AI. Both made significant contributions. The responsibility for any errors lies with the human author.

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Fasting has many possible benefits, and has been used by a lot of people in the anti-aging community. But a question sometimes comes up as to whether it’s safe to fast, or to fast regularly, as we get older.

There is no “cut off” age after which fasting suddenly becomes dangerous, but as the aging process kicks in, problems can occur that it is important to be aware of.

A Note from Nils

In my own case, I’ve done a lot of fasting and have benefited from it in the past. I went through a period of several years during which I had health issues that were difficult to get a handle on; I got conflicting diagnoses from different doctors. I never did get a completely satisfactory diagnosis. But in a sense that turned out not to matter, because fasting helped me resolve them. I did several five day water fasts, and at the end of them, my health problems had all cleared up.

So I’m aware of its benefits (which can be profound) on a personal level. But at the time I’m writing this, I’m 72 1/2 years old. I’ve noticed that my body responds a little differently than it did when I fasted when I was younger So I’ve eased off on the prolonged multi day water fasting. I’m not sure if I’ll ever do that kind of fast again.

I still sometimes do 36 hour water fasts, being sure to take electrolytes, but more often, if I feel like fasting, I’ll do some intermittent fasting. I might, for example, skip breakfast or skip both breakfast and lunch and just eat dinner. Now and then, I’ll fast from (for example) dinner on Monday till dinner on Tuesday, a 24 hour fast.

When I do this, I make sure that both dinners are high in all of the essential nutrients including protein. The goal is that even though I will have skipped a meal or two, I will have still gotten all of the nutrition that I need. There’s a little evidence to suggest that we “need” to be constantly eating; but there is a lot of evidence that we need a certain amount of nutrition every day, whether we get it in the form of one meal or three or five.

One problem is that once we get into our 70s, we are more prone to experiencing problems such as muscle wasting and sarcopenia, because we are likely to have a greater anabolic resistance. Dr Rhonda Patrick recently noted that we can compensate for this by eating more protein, in particular animal proteins, which become extremely important when we get older. Dr Longo himself, though he generally advocates more of a plant-based diet, once wrote about a woman in her 90s who was able to regain her health by eating only meat, and in her case, interestingly, the meat had to be raw. I’m not saying we should all go around eating raw meat, just that our dietary needs can change as the aging process kicks in. 

Water Fasting vs. Intermittent Fasting

Most people are aware of some basic information about water fasting. They know for example that it’s about consuming only water for an extended period. But there are actually many types of fasts. It’s important to be aware, for example, of the differences between prolonged water fasting and intermittent fasting. Their effects on the body at any age are very different, and the differences become even more important to understand for those of us who are older.

Water fasting means going for long stretches of time consuming nothing but water. We’re talking complete abstention from all food, often for extended periods. Some people do water fasting for days or even weeks, though it’s important to be aware that there can be extreme dangers for some people, in some situations, in doing water fasting.

Intermittent fasting (IF), on the other hand, involves alternating between eating and fasting within much shorter timeframes. Think 16:8 (fasting for 16 hours, eating during an 8-hour window) or 5:2 diets (eating normally five days a week, significantly reducing calories on two days).

This distinction matters because most of the recent research—especially in older populations—has actually focused on intermittent fasting rather than prolonged water fasting. Keep this in mind as we explore the findings.

Potential Benefits: What the Research Shows

Let’s start with the encouraging news. There are some genuinely interesting findings about fasting and health in older adults, particularly when it comes to brain function and metabolic health.

Cognitive Function and Brain Health

According to some fascinating recent research: fasting might actually support brain health as we age. A 2024 study looked at 40 older adults (all cognitively intact but with insulin resistance) and found that both 5:2 intermittent fasting and a healthy living diet led to some pretty promising results over just 8 weeks. We’re talking reduced neuronal insulin resistance, slower pace of brain aging, and improvements in executive function and memory.

Another 2024 study found that strategic fasting might help defend the brain against cognitive decline. Inflammation appears to be a potential culprit in dementia, and fasting may help address this.

Metabolic Health Improvements

The cellular benefits are fascinating too. Studies show that fasting can promote “cellular rejuvenation”—essentially, cells appear healthier and biologically younger in people following restricted eating patterns.

Beyond the cellular level, intermittent fasting has shown promise in counteracting some of the molecular hallmarks of cardiovascular aging. We’re seeing improvements in blood pressure and blood sugar control, which are obviously important for heart health as we age.

Weight Management

Water fasting does lead to weight loss—that’s pretty straightforward. It creates a calorie deficit and encourages your body to burn stored fat for energy. Research also shows it can help reduce high blood pressure and improve how your body handles insulin.

But these potential benefits need to be weighed very carefully against the risks, especially for older adults.

Significant Risks in Elderly Populations

The risks of water fasting for elderly individuals are well-documented, substantial, and in some cases, significant. Let’s walk through them.

Muscle Loss and Sarcopenia

As we age, maintaining muscle mass becomes increasingly importan, and increasingly challenging. The medical term for age-related muscle loss is “sarcopenia.” It contributes to frailty, falls, and loss of independence.

Humans do have some protective mechanisms during fasting. We don’t just immediately start breaking down all our muscle tissue. There are protein-sparing processes that kick in to limit the initial loss of skeletal muscle protein. Still, sarcopenia remains a danger.

A 2025 study using advanced imaging found that after 12 days of modified fasting (250 calories per day), skeletal muscle volume decreased by 5.4%. The researchers noted that much of this appeared to be glycogen and water loss rather than actual muscle tissue breakdown—which sounds reassuring. However, animal studies show us something interesting: When adult mice and old mice both fasted for 48 hours, the adult mice lost more muscle, while old mice showed more protection. This suggests our metabolism adapts as we age, but it doesn’t mean fasting is risk-free for older adults.

The bottom line is that the functional limitations that come with sarcopenia—difficulty walking, increased fall risk, loss of independence—contribute significantly to reduced quality of life and increased mortality in older adults. This makes muscle preservation absolutely critical.

Dehydration and Electrolyte Imbalances

If muscle loss is concern number one, dehydration and electrolyte problems are a close second. Between 17% and 28% of older adults in the United States are already dealing with dehydration, even without fasting. When dehydration becomes severe, it can lead to confusion, dangerously low blood pressure, and multiple organ dysfunction.

Why are older adults so vulnerable? One reason is that. after age 40, our kidneys start to change. There’s an increase in something called cortical glomerulosclerosis (basically, scarring in the kidney), and both the filtration rate and blood flow through the kidneys decline. This means the kidneys become less efficient at managing fluid balance—they have trouble both concentrating urine when we need to conserve water and diluting it when we need to get rid of excess.

The most common electrolyte problems in elderly folks are what doctors call “dysnatremias”—basically, having too much or too little sodium in the blood. And here’s the kicker: Age itself is an independent risk factor for developing both conditions.

Now, add fasting to this picture. During fasting, insulin levels drop, which causes the kidneys to release more sodium and water. It’s like a natural diuretic effect. While this might sound beneficial for reducing bloating, it also increases the risk of dehydration and electrolyte imbalances. If you’re not replenishing these minerals, you can develop symptoms like dizziness, muscle cramps, fatigue, and brain fog.

For elderly individuals—especially those already dealing with high blood pressure or heart conditions—the potential for blood pressure fluctuations during fasting is another concern. We’re talking about increased risks of cardiovascular events, orthostatic hypotension (that dizzy feeling when you stand up), and falls, which can have devastating consequences for older adults.

Bone Health Concerns

The impact of fasting — especially prolonged water fasting — on bone health is particularly concerning for elderly populations who are already at elevated risk for osteoporosis.

The challenge is that most studies on fasting and bone health haven’t specifically focused on the groups most at risk—elderly individuals and postmenopausal women. They’re often excluded from research, even though they’re the ones who would be most affected by any negative impacts on bone health. What we do know is that weight loss through calorie restriction tends to reduce bone mass and can negatively affect bone microstructure. This happens through several mechanisms: mechanical unloading (less weight bearing down on the bones), nutrient deficiencies, and changes in hormones that affect bone health.

Animal studies have shown that changes in bone quality caused by even just a few days of fasting can persist long-term, even after normal eating resumes. If you’re trying to prevent osteoporosis—which should be a priority for older adults—this is noteworthy and is another reason to be cautious if you’re considering fasting.

Cardiovascular Risks

This one’s a little tricky. Many studies have found that intermittent fasting has and cardiovascular benefits. But most of those studies have been done on younger, healthy people or those who are overweight or obese. At this point, we. don’t have enough good data on what happens when elderly individuals or people with existing cardiovascular disease try fasting.

Nutritional Deficiencies

This one’s pretty straightforward: Many older adults already struggle with getting adequate nutrition. They may have smaller appetites, difficulty chewing or swallowing, limited mobility that makes food preparation challenging, or they may be on fixed incomes that limit food choices. If you do fast, it’s vitally important to make sure that you’re getting enough nutrition during the meals when you are eating. If you’re already struggling to get in enough calories and nutrients, fasting it’s not a good idea.

Who Should NOT Water Fast

Medical sources are pretty unequivocal on this: Adults over age 75 should not water fast, or should only consider it under extremely strict medical supervision.

If someone does want to explore water fasting, it’s important to get a thorough examination first: medical history, physical exam, neurological and psychological assessment first to rule out contraindications.

It’s important to talk to your doctor before fasting, and consult with him or her in regard to changes in your prescription medicines, if you are in one of these groups:

• People with eating disorders or who are already underweight (low BMI)
• Those with specific medical conditions, like diabetes requiring certain medications
• Anyone taking medications that can’t be safely stopped
• Individuals with dementia or cognitive impairment (which significantly increases the risk of dangerous sodium imbalances)
• Those with active kidney disease or heart conditions

When prolonged water fasting is done under proper supervision, it involves things like:

• 24-hour medical supervision
• Vital signs checked periodically — sometimes twice daily
• Weekly laboratory monitoring
• Carefully structured refeeding periods lasting at least half the duration of the fast

Safer Options for Older Adults

If you’re an older adult interested in the potential benefits of fasting but concerned about the risks, are there safer alternatives?

Actually, there are. One is the FMD.

Fasting-Mimicking Diets (FMD)

Think of a fasting mimicking diet as a “soft fast” or “fasting lite.”

Instead of consuming nothing but water for days on end, an FMD involves eating very small amounts—typically 250-500 calories per day—for a short, defined period (usually 4-5 days). The diet is carefully designed to be low in protein and carbohydrates but relatively higher in healthy fats.

Doing an FMD is a little tricky for older adults, because for those of us who are in our 50s or older, it’s vitally important that we get enough protein in our lives. A fasting mimicking diet is a special exception in which protein is deliberately kept low for a very limited period of time in order to force the body into a condition called autophagy, during which it scavenges our cells for amino acids that it can turn into the building blocks of protein; this can be highly beneficial because it finds things like bacteria and viruses that we really don’t want in our bodies, and gets rid of them in the process.

This specific combination of very low calories and particular macronutrient ratios appears to trigger many of the same metabolic changes as complete water fasting. Your body shifts into similar modes—burning fat for fuel, triggering cellular cleanup processes, affecting insulin and other hormones—but you’re still getting some nutrition. You’re essentially tricking your body into thinking it’s fasting while still providing it with minimal sustenance.

What does FMD actually look like in practice?

There are many types of fasting mimicking diets; I described some of them in other articles in this website. The most well-studied FMD protocol (called the Buchinger Method, widely used in clinical settings in Europe) typically includes:

• Vegetable broths
• Vegetable juices
• Tiny amounts of honey
• Plenty of water and herbal teas

Each day provides around 250-500 calories total. It’s not a feast, certainly, but it’s also not the zero-nutrition challenge of water-only fasting.

The duration is typically 4-5 days—short enough to be manageable, long enough to potentially produce metabolic effects. Compare this to water fasting protocols that often run 7-14 days or longer, and you can see why FMD might be more approachable.

Why might FMD be more suitable for elderly individuals?

Several reasons make FMD potentially safer for older adults:

1. Less extreme stress on the body. You’re still getting micronutrients, some electrolytes from broths, and small amounts of energy. This reduces (though doesn’t eliminate) the risks of severe dehydration and electrolyte imbalances.
2. Shorter duration. Four to five days is much more manageable than the 7-14+ day water fasts that are common in research studies. Less time in a depleted state means less opportunity for complications.
3. Better compliance. The truth is that. consuming absolutely nothing but water for days is really hard, especially when you’re not feeling well or experiencing side effects. Having something to consume, even if it’s minimal, makes the protocol more tolerable. In that survey of older adults I mentioned earlier, about two-thirds said they’d find a brief fasting duration more acceptable, which suggests FMD’s shorter timeframe would appeal to this group.
4. Maintained (some) nutrient intake. While 250-500 calories isn’t much, it’s infinitely more than zero. For older adults who may already be at nutritional risk, this buffer could make a real difference.
5. Less muscle loss risk. While we don’t have extensive research comparing muscle loss between FMD and water fasting specifically in elderly populations, the logic suggests that providing some calories and some protein (even if minimal) would be protective compared to complete abstention.

Important cautions about FMD

Just because FMD is potentially safer than water fasting doesn’t mean it’s risk-free, especially for elderly individuals:

• Medical supervision is still recommended. While FMD is less extreme, it’s still a significant intervention that should be discussed with your healthcare provider first.
• Pre-existing conditions matter. If you have diabetes, kidney disease, heart conditions, or are taking certain medications, FMD might still pose risks.
• The refeeding period is crucial. How you come off even a modified fast matters enormously. Jumping straight back into normal eating can cause problems; there needs to be a gradual transition.
• Individual responses vary. Some older adults might tolerate FMD well; others might still experience significant side effects like fatigue, dizziness, or electrolyte issues.
• It’s not a magic bullet. FMD shouldn’t be seen as a substitute for an overall healthy dietary pattern. Think of it more as an occasional intervention (if appropriate for you) rather than a regular practice.

How to approach FMD if you’re interested

If you’re an older adult considering a fasting-mimicking diet:

1. Start with your doctor. Share information about FMD protocols and have an honest conversation about whether it might be appropriate given your health status.
2. Get baseline labs. It’s helpful to know your starting point for things like electrolytes, kidney function, and blood sugar before and after.
3. Consider a medically supervised program. Some clinics specialize in medically supervised fasting protocols and can provide monitoring throughout the process.
4. Don’t go it alone the first time. If your doctor approves trying FMD, consider having someone check on you daily, especially if you live alone.
5. Have a backup plan. Know what symptoms should prompt you to stop the fast and eat, and have appropriate foods readily available.
6. Plan your refeeding carefully. The transition back to normal eating should be gradual—usually starting with easily digestible foods like fruit, then adding vegetables, then proteins and more complex foods over several days.

Time-Restricted Feeding (TRF): An Even Gentler Option

Time-restricted feeding deserves mention as perhaps the most accessible form of fasting for elderly individuals. With TRF, you’re not reducing your total daily calories—you’re just limiting the window of time during which you eat them.

The most common approach is 16:8—fasting for 16 hours (including sleep time) and eating all your meals within an 8-hour window. For example, you might eat between noon and 8 PM, then fast from 8 PM until noon the next day. Other ratios (like 14:10 or 18:6) are also used.

Why TRF might be particularly suitable for older adults:

• No calorie restriction. You’re still eating your full nutritional needs, just in a compressed timeframe. This addresses one of the biggest concerns with fasting in elderly populations—inadequate nutrition.
• Can maintain protein intake. As long as you’re eating enough protein during your eating window, you can still hit that important goal of 1.2+ grams per kilogram of body weight daily to preserve muscle.
• More sustainable long-term. Unlike multi-day fasts that are occasional events, TRF can potentially be maintained as a daily practice if it works for you.
• Simpler to implement. Once you establish your eating window, it’s pretty straightforward—no complicated meal planning or calorie counting for special fasting days.
• Still potentially provides metabolic benefits. Research suggests that TRF can improve insulin sensitivity, support cellular cleanup processes (autophagy), and align better with our natural circadian rhythms.

Important considerations for TRF in older adults:

• Medication timing matters. If you take medications with food, you’ll need to figure out how to fit them into your eating window, or TRF might not work for you.
• Social factors. If your eating window doesn’t align with family meals or social eating patterns, that can be challenging.
• Hunger and energy levels. Some people adapt quickly to TRF; others find the hunger during fasting hours difficult, especially at first.
• Risk of inadequate intake. For some older adults, compressing all eating into a shorter window might make it harder to consume enough calories and nutrients overall. This needs to be monitored.

The research on TRF in older adults is still developing, but early findings suggest it may offer metabolic benefits with a more manageable risk profile than prolonged fasting. Still, as with any dietary change, medical consultation is wise before starting.

Interest Among Older Adults

It’s worth noting that older adults themselves are quite interested in fasting. A survey of 290 people aged 65 and over (average age 73.8 years) found some pretty striking numbers:

• More than half (51.7%) had already tried fasting
• About 81% found the idea of therapeutic fasting interesting
• 83% said they’d be willing to fast if it were proven beneficial for their health
• 77% would fast if it could help decrease the burden of chronic diseases

This tells us two things: First, there’s clearly significant interest in fasting among older adults. Second, there’s a real need for proper education about both the potential benefits and the very real risks. Interest alone isn’t enough—people need good information to make informed decisions about their health.

Warning Signs and Red Flags

If you’re an older adult who has decided to try any form of fasting (even modified approaches like a fasting mimicking diet (FMD) or time-restricted feeding), you need to know what warning signs require immediate action. These symptoms could indicate life-threatening complications:

Cardiac/Circulatory:

• Chest pain or pressure
• Severe heart palpitations or irregular heartbeat
• Extreme dizziness or fainting, especially when standing
• Shortness of breath or difficulty breathing

Neurological:

• Severe confusion or disorientation (not knowing where you are, what day it is, or not recognizing familiar people)
• Seizures or convulsions
• Severe headache that’s sudden and unlike any you’ve had before
• Slurred speech or difficulty speaking
• Visual changes or loss of vision

Other Critical Signs:

• Severe, persistent vomiting (can’t keep water down)
• Blood in vomit or stool
• Complete inability to urinate or very dark urine (looks like tea or cola)
• Extreme weakness where you can’t stand or walk safely

Do not try to “push through” these symptoms. They could indicate severe dehydration, dangerous electrolyte imbalances, cardiac arrhythmias, or other serious complications.

These symptoms suggest complications that need medical evaluation:

Dehydration and Electrolyte Issues:

• Persistent dizziness or lightheadedness, especially when standing
• Severe muscle cramps or spasms (particularly in legs, feet, or hands)
• Heart palpitations (feeling your heart racing, fluttering, or skipping beats)
• Extreme dry mouth that doesn’t improve with water intake
• Decreased urination or very concentrated (dark yellow/amber) urine
• Persistent nausea

Cognitive/Neurological:

• Significant difficulty concentrating or confusion
• Severe brain fog that impairs your ability to do normal tasks
• Changes in mental state or mood (unusual irritability, anxiety, or depression)

Physical Symptoms:

• Severe, persistent weakness that makes daily activities difficult
• Trembling or shaking that you can’t control
• Significant difficulty sleeping or new insomnia
• Pins and needles sensations or numbness in extremities

Metabolic Concerns:

• If you’re diabetic: blood sugar readings outside your target range (especially below 70 mg/dL or above 250 mg/dL)
• For anyone: feeling cold all the time or inability to warm up
• Unusual swelling in feet, ankles, or hands

When these symptoms are tolerable and mild, they might be normal adjustment responses, especially in the first 1-3 days. However, if they:

• Persist beyond the first few days
• Get worse instead of better
• Interfere significantly with your daily life
• Feel concerning to you intuitively

Then it’s time to break the fast and check in with your healthcare provider.

Special Considerations for Elderly Individuals

As an older adult, you need to be especially vigilant about:

Falls and Balance:

• Even mild dizziness can lead to falls, which can have serious consequences for older adults
• If you feel unsteady on your feet at all, stop the fast
• Consider using a cane or walker during fasting periods if you have any balance concerns
• Don’t attempt stairs if you’re feeling dizzy or weak

Medication Interactions:

• Blood pressure medications combined with fasting can cause dangerous drops in blood pressure
• Diabetes medications need careful management during any fasting
• If you’re on diuretics (“water pills”), you’re at higher risk for dehydration and electrolyte imbalances

Cognitive Changes:

• Memory or confusion in older adults is sometimes dismissed as “normal aging,” but during fasting, it can signal serious problems
• If you or those around you notice cognitive changes, take them seriously

Slower Recovery:

• Older adults may take longer to recover from complications
• What might be a minor issue for a younger person could be more serious for you
• Err on the side of caution—it’s always better to stop a fast early than to push through and risk serious complications

Practical Safety Measures

If you’re attempting any form of fasting, particularly if you’re elderly and living alone, or have health conditions:

1. Make sure someone (a family member, friend, or neighbor) knows you’re fasting and can check on you daily.

2. Keep emergency contacts visible. Have your doctor’s number, an emergency contact, and 911 posted where you can easily see them.

3. Have appropriate foods available. Keep easily digestible foods on hand (fruit juices, fresh fruits, vegetable broth) so you can break the fast immediately if needed.

4. Monitor your vital signs if possible. If you have a blood pressure cuff at home, check your blood pressure at least once daily. Note any significant changes.

5. Stay hydrated. During any fast, drink at least 2-3 liters of water daily. For modified fasts, consider adding electrolyte supplements (with your doctor’s approval).

6. Keep a symptom journal. Note how you’re feeling each day. This can help you and your doctor evaluate whether fasting is appropriate for you and spot patterns in symptoms.

7. Trust your instincts. If something feels wrong, it probably is. There’s no prize for completing a fast if it’s harming your health.

The Bottom Line on Warning Signs

Your body is remarkably good at telling you when something’s wrong. The danger comes when people dismiss warning signs or try to push through symptoms because they’re committed to completing the fast.

Remember: Stopping a fast isn’t failing. It’s making a wise health decision. There’s always another day to try again (with modifications, better preparation, or the realization that fasting isn’t right for you). But you only get one body, and protecting it should always be the priority.

Conclusions and Recommendations

Alright, let’s bring this all together. What’s the bottom line on water fasting for elderly individuals?

Risks versus Benefits:

Here’s what we know: Fasting shows genuine promise for cognitive function, metabolic health, and cellular rejuvenation. Those benefits are real and exciting. But there are risks also, particularly for people in our age group. Risks that are well-established, well-documented, and serious include:

• The dangers of sarcopenia and muscle loss
• Severe dehydration and electrolyte imbalances
• Bone density concerns
• Cardiovascular complications
• Falls and injuries
• Medication interactions

A few key points:

1. Don’t attempt water fasting without medical supervision. If you’re an elderly individual considering this, or have any health problems that might be concerns, a comprehensive pre-fasting medical evaluation is essential.

2. If you’re over 75, consider safer approaches instead. Fasting-mimicking diets or time-restricted eating patterns have more research support in older populations and carry fewer risks than prolonged water fasting.

3. Intermittent fasting protocols (like 16:8 time-restricted eating or 5:2 diets) have more evidence backing them up for older adults and pose fewer risks than water fasting. But you should still talk to your doctor before starting.

Summing Up

If you’re an elderly individual interested in the potential benefits of fasting, here’s what I’d recommend:

• Talk to your healthcare provider first. Not just a conversation, but a thorough discussion of your specific health status, medications, and risk factors.
• Consider safer alternatives. Modified fasting approaches like fasting-mimicking diets or time-restricted eating might give you some of the benefits with significantly lower risks.
• Prioritize proven dietary patterns. Make sure you’re getting enough protein, healthy fats, and other important nutrients in your diet before considering fasting. If you’re malnourished, fasting is never a good idea..
• Focus on what matters most: Adequate nutrition, proper hydration, maintaining muscle mass, and staying active. These aren’t exciting or trendy, but they’re the foundations of healthy aging.
• If you’re on any medications or managing any chronic health conditions, the standard advice is to check with your doctor before starting a fast. They may need, for example, to adjust your medications.

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References

Everything in this article is grounded in peer-reviewed research from respected journals. Here are the key studies and sources cited:

Brain Health and Cognitive Function

1. Kapogiannis D, Manolopoulos A, Mullins R, et al. Brain responses to intermittent fasting and the healthy living diet in older adults. Cell Metabolism 2024; 36(8):1668-1678. Read the full study

Muscle Loss and Sarcopenia

2. Naëgel A, Viallon M, Ratiney H, et al. Impact of Long-Term Fasting on Skeletal Muscle: Structure, Energy Metabolism and Function Using 31P/1H MRS and MRI. Journal of Cachexia, Sarcopenia and Muscle 2025; 16(2):e13773. Read the full study
3. Laurens C, Grundler F, Damiot A, et al. Is muscle and protein loss relevant in long-term fasting in healthy men? A prospective trial on physiological adaptations. Journal of Cachexia, Sarcopenia and Muscle 2021; 12(6):1690-1703. Read the full study
4. Moro T, Tinsley G, Pacelli FQ, et al. Time-restricted eating and age-related muscle loss. Nutrients 2019. Read the full study

Cardiovascular Health and Aging

5. Stein J, Zmudzka-Cichocka K, Opala M. Risks and Benefits of Intermittent Fasting for the Aging Cardiovascular System. Canadian Journal of Cardiology 2024. Read the full study

Safety of Water Fasting

6. Finnell JS, Saul BC, Goldhamer AC, Myers TR. Is fasting safe? A chart review of adverse events during medically supervised, water-only fasting. BMC Complementary Medicine and Therapies 2018; 18:67. Read the full study

Fasting-Mimicking Diets and Modified Approaches

7. Gramont B, Killian M, Bernard E, et al. Therapeutic Fasting: Are Patients Aged 65 and Over Ready? Nutrients 2022; 14(10):2001. Read the full study

Dehydration and Electrolyte Balance in Elderly

8. Adult Dehydration. StatPearls [Internet]. Updated March 2025. Read the full article
9. Leiper JB. Electrolytes in the Aging. Advances in Chronic Kidney Disease 2010. Read the full study
10. Zhang N, Du SM, Ma GS. Hydration Status in Older Adults: Current Knowledge and Future Challenges. Nutrients 2023. Read the full study

Bone Health and Fasting

11. Mumford SL, Dastouki Z, Butera G, et al. Intermittent fasting and bone health: a bone of contention? British Journal of Nutrition 2023; 130(12):2025-2040. Read the full study
12. Veronese N, Stubbs B, Punzi L, et al. The effects of calorie restriction, intermittent fasting and vegetarian diets on bone health. Aging Clinical and Experimental Research 2019; 31(6):753-758. Read the full study
13. Liu Z, Dai X, Zhang H, et al. The Effects of Different Dietary Patterns on Bone Health. Nutrients 2024; 16(14):2289. Read the full study

Additional Resources

14. Intermittent Fasting: Is It Safe If You’re 50 or older? AARP December 2024. Read the article
15. Water fasting: Benefits, risks, and how to do it. Medical News Today Updated May 2025. Read the article

Note on Research Access

Some studies linked above may require institutional access or payment to view the full text. PubMed links will always provide at least the abstract. Many studies include free full-text options—look for “PMC” links or “Free article” designations.

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A note on using this information: This article is meant to educate and inform, not to provide medical advice for your specific situation. Everyone’s health circumstances are different, and what’s right for one person may not be appropriate for another. Please talk with qualified healthcare professionals who know your medical history before making any significant changes to your diet or lifestyle—especially when it comes to something as impactful as fasting. Your doctor is your partner in health decisions, not an obstacle to overcome.