The bottom line. We should all be drinking plenty of water every day, but not in lieu of eating! The Mayo Clinic suggests drinking nine beverages a day—if you want to make them cold to try to shed a few extra calories, go right ahead. But if you want to lose weight and keep it off, a water diet is not the way to go.
Water fasting will likely result in lean muscle wasting, or muscle mass loss that occurs when you don't take in protein, she says. To compensate, your body starts to break down muscles. You might develop other nutrient deficiencies as well.
"Drinking water is not going to have a huge weight loss effect, and without calorie restriction and/or exercise, just drinking water is not likely to lead to significant weight loss," Jampolis says. As always, she says, it's important to embrace a more comprehensive and sustainable approach.
Full liquid diets are usually used for a few days and up to two weeks. Side effects include constipation, diarrhea, fatigue, tiredness, and weight loss.
Some people who try the fasting diet for 3 days do it as a way to lose weight. While people do lose weight, it is important to note that the weight loss is water weight and not fat loss. Research has shown a positive correlation between increased water consumption and weight loss.
Although you will have lost weight during the fast (around 1-2 pounds per day) if you go from zero calories for 5 days straight into eating whatever you want on day 6, you could actually gain all of that weight back plus more because of how your body reacts to sudden refeeding.
Fasting for a week may result in adverse health and metabolic changes such as dehydration, a loss of lean muscle mass, hyperuricemia, hyponatremia, protein-sparing, sodium, and potassium-sparing, decreased serum calcium and magnesium levels, and acidic urine.
2 Days to a Week
After two to three days of not eating, the brain will start screaming for glucose to keep from shutting down. To get it the human body will start to break down muscle tissue and other protein sources to get energy. This will lead to even more fatigue and muscle atrophy, as well as cramps and diarrhea.
After two or three days without food, your body starts to break down fatty tissue. Your muscles use the fatty acids created during this process as their main source of fuel. Fatty acids are also used to form ketones in the liver. Ketones are another substance the body can use for energy.
A water fast is when a person does not eat and drinks nothing other than water. There is no set time that water fasting should last for, but medical advice generally suggests anywhere from 24 hours to 3 days as the maximum time to go without food.
In general, it is likely that a person could survive between 1 and 2 months without food. As many different factors influence the length of time that the body can last without food, this period will vary among individuals.
An average woman needs 2,000 calories every day if she rests and eats nothing (6). So, if you do not eat anything for 2 days, you will technically already have a 4,000 calorie deficit. That means you have just smidgen over one pound without eating anything for 48 hours.
Bottom line: skipping meals rarely results in weight loss for the long term and it can negatively impact your metabolism.
There are many side effects to not eating. While you may lose weight in the short term, it is not a healthy or sustainable weight loss solution. Your metabolism slows down, you burn lean muscle and store fat, and your body's overall function decreases.
In the 1971 edition of The Guinness Book of Records, Barbieri's 382-day fast was recognized as the longest recorded. In 1973, Dennis Galer Goodwin went on a hunger strike for 385 days, but he was force-fed during this period.
As starvation progresses, the physical symptoms set in. The timing of these symptoms depends on age, size, and overall health. It usually takes days to weeks, and includes weakness, fast heart rate, shallow breaths that are slowed, thirst, and constipation. There may also be diarrhea in some cases.
Eating one meal a day can increase your blood pressure and cholesterol. This occurred in a group of healthy adults who switched to one meal a day to participate in a study. If you already have concerns in either area, eating just once a day might not be safe. Eating one meal late can cause your blood sugar to spike.
It's very important to speak with your doctor before trying prolonged fasting. Medical supervision will help ensure that 5 day water fasting does not put your health in danger, and your doctor may have specific concerns or recommendations for safer fasting practices.
Although studies suggest that prolonged fasting can be safe, water fasting for three days is often not recommended nor safe for some people, and there are usually healthier, less severe alternatives for weight management and perceived health benefits.