I took on a 3-day fasting challenge, after being inspired by hearing about all the benefits a 3 day fast can give you. And by the fact that my weight loss has been holding steady lately while I want to see the scale moving down. All of it motivated me to try a three-day water fast.
Fasting for a few days or more has become popular in recent years. It’s when you drink only water and don’t eat any food. Many people use it for weight loss, “detoxing,” or to improve their overall health.
Benefits of a Three-Day Water Fast
The 3 day water fast is thought to have some amazing benefits. However, more research is needed on exactly how fasting affects the body, some studies have shown that water fasting may provide the following health benefits2:
- Promote autophagy: Autophagy is a process where your body breaks down and recycles old parts of your cells2. This process may help protect against diseases like cancer, Alzheimer’s, and heart disease2. For example, autophagy may prevent damaged parts of your cells from accumulating, which is a risk factor for many cancers2.
- Lower blood pressure: Some studies show that longer water fasts may help lower blood pressure in people with high blood pressure2. One study found that water fasting helped reduce systolic blood pressure in participants who were overweight or had obesity3.
- Improve insulin and leptin sensitivity: These hormones play a vital role in metabolism. Increased sensitivity may help your body regulate blood sugar levels and process hunger signals more efficiently, which may help lower the risk of obesity2.
- Lower the risk of several chronic diseases: There’s some evidence that water fasting may lower the risk factors for chronic diseases like diabetes, cancer, and heart disease2. For example, some research suggests that water fasting may protect the heart against damage from free radicals2. In addition, studies in animals and humans have found that water fasting may suppress genes that help cancer cells grow2.
- Promote weight loss: Water fasting creates a calorie deficit and may help the body burn fat for fuel4. However, it’s important to note that much of the initial weight loss may come from water, carbs, and even muscle mass, not just fat2.
- Improve heart health: Water fasting may improve several factors related to heart health, including blood pressure and cholesterol levels3.
Unfortunately, most of the research on water fasting is from animal or short-term studies. More high-quality human studies are needed to confirm the benefits.
Potential Risks of a 3 Day Fast
While a three-day water fast may offer some potential benefits, it’s crucial to be aware of the associated risks. Here are some of the potential risks of a three-day water fast:
- Dehydration: Even though you’re only consuming water, it’s possible to become dehydrated if you don’t drink enough. This is because about 20-30% of your daily fluid intake comes from food. Symptoms of dehydration include dizziness, nausea, headaches, and low blood pressure5.
- Orthostatic hypotension: This is a sudden drop in blood pressure when you stand up, which can cause dizziness and lightheadedness. It can be caused by dehydration and may increase the risk of falls5.
- Electrolyte imbalances: Fasting can disrupt electrolyte balance, especially sodium levels. This can lead to fatigue, headaches, and muscle weakness6.
- Nutrient deficiencies: Prolonged fasting can deprive your body of essential nutrients. This is a concern, especially for older adults who may already have lower nutrient reserves5.
- Refeeding syndrome: This is a serious condition that can occur when food is reintroduced too quickly after a prolonged fast. It can cause dangerous shifts in fluid and electrolyte level6.
- Worsening of existing health conditions: Water fasting may worsen certain health conditions, such as gout, eating disorders, and kidney disease5.
- Other side effects: Common side effects of fasting include hunger, fatigue, headaches, lightheadedness, and mood changes.
It’s important to consult your doctor before starting a water fast, especially if you have any health conditions or take medications. If you experience any severe or persistent side effects during the fast, stop immediately and seek medical attention.
I thought it was worth trying
I was a bit nervous. I wasn’t sure I could go the distance. I was worried about feeling weak, and hungry. But I was also excited to see how my body would adapt if I would experience any benefits like increased energy or mental clarity.
On the first day, I woke up feeling normal. I’m used to doing the sixteen-hour intermittent fast. So, I really didn’t notice any big changes. I did feel a bit hungry at the sixteen-hour mark. But I managed to make it through the day without eating.
On the second day, at forty-four hours in I started to feel weak and hungry. I began to wonder, if I feel like this at forty-four hours how will I ever make it to seventy-two? I just drank more water. And I noticed that I slept better.
On the third day I woke up feeling weak and sluggish, but I wasn’t hungry. I got up and it felt like I was walking around in a fog. I had snapped out of it by the time I was dressed and ready for work. But I started thinking about food. I found myself meal planning for the day after the 72 hour fast.
And Then I finished the fast. I can’t say that my thoughts are clearer, or that I feel more focused than usual. But I am pleased with myself for pushing through and finishing the challenge.
Looking back on this experience, I’ve learned some valuable lessons. I’ve learned that my body is capable of so much more than I thought. I can survive reasonably well for 3 days without food. I need to be more mindful of the queues my body sends me. And sometimes hungry can mean thirsty. The water really helped to banish my hunger. I find that amazing!
If you’ve ever considered fasting a day or more or have any thoughts on the topic, let me know in the comments below. 👇🏽
Works cited
1. Water fasting: Benefits, risks, and how to do it – MedicalNewsToday, accessed February 18, 2025, https://www.medicalnewstoday.com/articles/319835
2. What Are the Benefits (and Dangers) of Water Fasting? – Healthline, accessed February 18, 2025, https://www.healthline.com/nutrition/water-fasting
3. What To Know About the Benefits and Risks of Water Fasting – Health, accessed February 18, 2025, https://www.health.com/water-fasting-7556171
4. UNDERSTANDING WATER FASTING: BENEFITS, SAFETY, HOW TO GO ABOUT IT, accessed February 18, 2025, https://myacare.com/blog/understanding-water-fasting-benefits-safety-how-to-go-about-it
5. Water fasting: Benefits, risks, and how to do it
6.What Are the Benefits (and Dangers) of Water Fasting?
The Benefits Of Intermittent Fasting
This was such an interesting read! Your experience really highlights how convenient and available food is. That’s what really makes it so hard to fast. I’m curious—after going three days without it, did you find yourself changing any of your eating habits? Or have you gone back to eating pretty the same as before? Thanks for sharing your journey!
Thanks for your comment, Hanna. That’s a good question, because I don’t feel like my stomach is as big as it was before. I’ve been eating less in the past couple of days, than I was eating before the fast. I’ll see how long that lasts. I want to do another 3 day fast soon. So, I hope the changes last. 😊