Fasting, a practice of restricting food intake, has been part of human culture for millennia. Today, it's often pursued for health or weight loss reasons. Among various fasting methods, the "bread and water diet" is sometimes considered, often as a simplified or extreme approach to weight management. This article explores the risks and benefits associated with such a diet, comparing it to other fasting protocols and healthier dietary strategies.
Understanding the Bread and Water Diet
The bread and water diet, at its core, involves consuming only bread and water for a specific period. This drastically restricts calorie and nutrient intake, leading to weight loss. This diet is a severe form of calorie restriction and lacks essential nutrients. While it might lead to short-term weight loss, the potential risks outweigh the benefits.
Potential Risks of a Bread and Water Diet
- Nutrient Deficiencies: Bread and water alone do not provide all the essential vitamins, minerals, and macronutrients the body needs to function correctly. This can lead to deficiencies over time, impacting overall health.
- Muscle Loss: When the body doesn't get enough calories or protein, it may start breaking down muscle tissue for energy, reducing muscle mass.
- Metabolic Slowdown: Severe calorie restriction can slow down metabolism as the body tries to conserve energy, making it harder to lose weight in the long run.
- Dehydration: While water is allowed, the diet lacks the electrolytes and minerals found in other foods, potentially leading to dehydration.
- Health Complications: Individuals with pre-existing medical conditions like diabetes, kidney disease, or eating disorders should avoid this diet due to potential health complications.
- Unsustainable: The restrictive nature of the bread and water diet makes it difficult to maintain long-term, often leading to a rebound in weight gain once regular eating resumes.
- Disordered Eating: Such restrictive diets can trigger or worsen disordered eating patterns in some individuals.
- Other risks: Fatigue, irritability, headaches, lack of focus, decreased urination, and constipation. Dry fasting can also cause urinary, kidney, and lung issues, as well as nutritional deficiencies and eating disorders.
Potential Benefits (and Why They Might Not Be Worth It)
- Short-Term Weight Loss: The drastic calorie reduction will likely lead to weight loss in the short term. However, this is primarily water weight and muscle mass, not necessarily fat loss.
- Simplicity: The diet is straightforward and easy to follow, requiring minimal planning or preparation.
The Fasting Mimicking Diet (FMD) as a Safer Alternative
The Fasting Mimicking Diet (FMD) is a dietary approach designed to replicate the benefits of intermittent fasting without the total food abstinence associated with traditional fasting. UCLA Health dietitian Shelby Yaceczko, DCN, RDN-AP, who specializes in clinical nutrition, provides insights into how FMD works, its potential health benefits, and what people should consider before embarking on this dietary plan.
As with any new diet plan, Dr. Yaceczko recommends first taking into consideration one’s overall health and talking it over with a health care provider.
Understanding the Fasting Mimicking Diet
The FMD is primarily plant-based and designed to produce fasting-like effects in the body by targeting blood glucose, ketone levels, and other biological markers. Unlike traditional fasting, which restricts almost all eating and drinking with the exception of water and certain other liquids, the FMD permits a limited intake of specific nutrients to sustain the body. The diet is often set up in cycles - such as five consecutive days per month over three months.
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“You can think of it as a low-calorie diet pattern designed to mimic fasting without fasting,” explains Dr. Yaceczko. “On an FMD, you’re allowed a limited intake of calories from specific food sources at certain times, so you won’t be completely fasting.” The diet focuses on a macronutrient ratio of approximately 10% protein, 45% fat, and 45% carbohydrates, Dr. Yaceczko says. Generally, individuals consume around 40%-50% of their usual calorie intake on the first day, then reduce to 10%-20% for the next four days.
Health benefits of the FMD
In recent studies, the FMD has shown promising results in weight management, metabolic health, and chronic disease risk reduction.
According to Dr. Yaceczko, documented benefits include weight loss, decreased belly and liver fat, reduced cholesterol and blood sugar levels, and lowered blood pressure. Additionally, the diet may help reduce inflammation and cell damage in the body, processes associated with aging and disease.
One of the unique aspects of the FMD is its potential influence on cellular health, particularly through a process known as autophagy. “FMD may potentially speed up autophagy, which eliminates bad cells in the body that cause disease and promote aging processes,” notes Dr. Yaceczko. This regenerative effect on cells is a key reason the diet is being studied for its effect on age-related diseases and cellular health.
Cardiovascular health and disease prevention
The FMD has also been linked to cardiovascular benefits. Some early findings suggest it may help reduce risk factors associated with heart disease, improve cholesterol levels and regulate blood pressure, which are vital components of heart health. Research on the FMD’s effects on chronic diseases such as diabetes, cancer, and Alzheimer’s disease is also ongoing, though most studies have been conducted only on animals. The potential of the FMD to support cancer treatment and recovery has drawn attention, as well. Though early studies have been promising, Dr. Yaceczko emphasizes caution. “The FMD is being studied for its ability to extend median lifespan, reduce inflammation and cancer incidence, and increase results from anti-cancer treatments, but much of the research has only been done in animal studies,” she says. As with any dietary intervention, clinical trials are essential to determine the FMD’s full effects on human health, Dr. Yaceczko says.
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Safety considerations and who should avoid the diet
Although the FMD offers a range of potential health benefits, it is not suitable for everyone. Individuals who are pregnant or breastfeeding, those with a history of eating disorders, and people with existing medical conditions such as diabetes, kidney disease, or heart disease, should consult with their health care provider if considering the diet. “Individuals who are considered at high risk of malnutrition or undernutrition should typically avoid fasting diet patterns,” Dr. Yaceczko warns. Additionally, those on medication should be sure to consult with a doctor before starting a fasting diet.
For those who do adopt the FMD, maintaining proper hydration is crucial. Dr. Yaceczko recommends consuming at least 70 ounces of water daily to prevent dehydration. The diet’s restrictive nature can also pose challenges, and long-term adherence may be difficult for some.
FMD vs. other fasting protocols
Unlike other intermittent fasting methods that require complete abstention from food for specific time intervals, the FMD allows for a limited amount of food intake. Dr. Yaceczko points out that this dietary flexibility can make the FMD more appealing to those who find traditional fasting too restrictive. “For some, the FMD may be easier to adopt, given it allows for certain foods and nutrients during fasting days,” she explains. By offering a structured yet less restrictive fasting experience, the FMD has opened a door for individuals who wish to explore the benefits of fasting without entirely eliminating food.
A typical FMD meal plan
The FMD primarily includes non-starchy vegetables such as celery, zucchini, tomatoes, and leafy greens, along with whole fruits including berries, apples, and oranges. Healthy fat sources such as avocados, walnuts, and olive oil are also allowed, providing essential fats while limiting protein and carbohydrate intake. The diet restricts high-glycemic foods such as white rice, white bread, bagels, refined sugars, processed foods, dairy, animal proteins, and starchy vegetables.
These dietary choices are intended to nourish the body while keeping calorie intake low enough to trigger fasting-like biological responses. However, Dr. Yaceczko stresses the importance of personalization. “It’s essential to talk with your health care provider for individual calorie targets,” she advises, as caloric needs vary based on age, weight, and health status.
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Is FMD right for you?
As interest in the diet grows, so does the need for more robust human studies to validate its safety and effectiveness, says Dr. Yaceczko.
“The Fasting Mimicking Diet is still a new diet pattern,” she says, “and we are learning more about it with new research studies coming out.” While the FMD may be an appealing way to enhance cellular health and support healthy aging, it is essential to proceed with caution and prioritize an individualized approach.
Water Fasting: An Overview
Water fasting is a type of fast during which you cannot consume anything besides water. Most water fasts last 24-72 hours. You should not follow a water fast for longer than this without medical supervision.
Here are a few reasons why people try water fasting:
- religious or spiritual reasons
- to lose weight
- for “detoxing”
- for its health benefits
- preparing for a medical procedure
The main reason why people try water fasting is to improve their health. In fact, several studies have linked water fasting with some impressive health benefits, including a lower risk of certain cancers, heart disease, and diabetes. Water fasting may also promote autophagy, a process in which your body breaks down and recycles old, potentially dangerous parts of your cells.
Popular diets like the lemon detox cleanse are modeled after the water fast. The lemon detox cleanse only lets you drink a mixture of lemon juice, water, maple syrup, and cayenne pepper several times per day for up to 7 days.
However, water fasting has many risks and can be very dangerous if followed for too long.
How to Water Fast
There are no scientific guidelines on how to start water fasting. However, several groups of people should not water fast without medical supervision.
If you have never water fasted before, it’s a good idea to spend 3-4 days preparing your body for being without food. You can do this by eating smaller portions at each meal or by fasting for part of the day.
Water fast (24-72 hours)
During a water fast, you are not allowed to eat or drink anything besides water. The water fast lasts for 24-72 hours. You should not water fast for longer than this without medical supervision because of health risks.
Some people may feel weak or dizzy during a water fast and may want to avoid operating heavy machinery and driving to avoid causing an accident.
Post-fast (1-3 days)
After the water fast, you should resist the urge to eat a big meal. This is because eating a large meal after a fast may cause uncomfortable symptoms.
Instead, break your fast with a smoothie or smaller meals. You can start introducing larger meals throughout the day as you feel more comfortable.
The post-fast phase is especially important after longer fasts. This is because you may be at risk of refeeding syndrome, a potentially fatal condition in which the body undergoes rapid changes in fluid and electrolyte levels.
This phase normally lasts a day, but people who fast for 3 or more days may need up to 3 days before they feel comfortable eating larger meals.
Potential Health Benefits of Water Fasting
Both human and animal studies have linked water fasting to a variety of health benefits.
- May promote autophagy: Autophagy is a process in which old parts of your cells are broken down and recycled. Several animal studies suggest that autophagy may help protect against diseases like cancer, Alzheimer’s, and heart disease. For example, autophagy may prevent damaged parts of your cells from accumulating, which is a risk factor for many cancers. This may help prevent cancer cells from growing. Animal studies have consistently found that water fasting helps promote autophagy. Animal studies also show that autophagy may help extend life span. That said, there are very few human studies on water fasting, autophagy, and disease prevention. More research is needed before recommending it to promote autophagy.
- May help lower blood pressure: Research shows that longer, medically supervised water fasts may help people with high blood pressure lower their blood pressure. One study in 48 people with overweight or obesity found that water fasting for an average of 17 days under medical supervision led to reductions in systolic blood pressure. It was also associated with improvements in levels of LDL (bad) cholesterol and inflammation. Similarly, another review concluded that water fasting could significantly reduce blood pressure levels and body weight in people with high blood pressure. Still, more research is needed to evaluate the link between short-term water fasts (24-72 hours) and blood pressure.
- May improve insulin and leptin sensitivity: Insulin and leptin are important hormones that affect the body’s metabolism. Insulin helps the body store nutrients from the bloodstream, while leptin helps the body feel full. Research shows that water fasting could make your body more sensitive to leptin and insulin. Greater sensitivity makes these hormones more effective. For example, being more insulin sensitive means your body is more efficient at reducing its blood sugar levels. Meanwhile, being more leptin sensitive could help your body process hunger signals more efficiently, and in turn, lower the risk of obesity.
- May lower the risk of several chronic diseases: There is some evidence that water fasting may lower the risk factors of chronic diseases like diabetes, cancer, and heart disease. In one 2013 study, 30 healthy adults followed a water fast for 24 hours. After the fast, they had significantly lower blood levels of triglycerides - a risk factor for heart disease. Some research also suggests that water fasting may protect the heart against damage from free radicals. Free radicals are unstable molecules that can damage parts of cells. They are known to play a role in many chronic diseases. Moreover, studies in animals and humans have found that water fasting may suppress genes that help cancer cells grow. It may also improve the effects of chemotherapy.
Risks and Side Effects of Water Fasting
Although water fasting may have some benefits, it comes with health risks.
- May lose the wrong type of weight: Unfortunately, a lot of the weight you lose in the beginning may come from water, carbs, and even a small amount of muscle mass.
- May become dehydrated: Although it sounds strange, a water fast could make you dehydrated. This is because roughly 20-30% of your daily water intake comes from the foods you eat. If you’re drinking the same amount of water but not eating foods, you might not be getting enough water. Symptoms of dehydration include dizziness, nausea, headaches, constipation, low blood pressure, and low productivity. To avoid dehydration, you may need to drink more than usual.
- May experience orthostatic hypotension: Orthostatic hypotention is defined as a drop in blood pressure that happens when you suddenly stand up, and it can leave you dizzy, lightheaded, and at risk of fainting. If you experience orthostatic hypotension while fasting, you may need to avoid driving or operating heavy machinery. The dizziness and risk of fainting could lead to an accident.
- May worsen several medical conditions: Although a water fast is relatively short, there are a few conditions that may be aggravated by water fasting. People with the following medical conditions should not water fast without first seeking advice from a healthcare professional:
- Gout: Water fasting may increase uric acid production, a risk factor for gout attacks.
- Eating disorders: There is evidence that fasting may encourage disordered eating behaviors for some people.
Water Fasting and Weight Loss
Like other types of fasting, water fasting can help you lose weight. However, it comes with plenty of health risks.
If you want to reap the benefits of fasting but also want to lose weight, intermittent fasting and alternate-day fasting are probably more effective approaches than water fasting for 24-72 hours. These fasts provide similar health benefits but can be followed for much longer periods, as they allow you to eat food, decreasing the risk of nutrient deficiencies.
Dry Fasting: A Dangerous Trend
Dry fasting is when you’re doing any other form of fasting, but you’re fasting without any fluid, so you’re not drinking water or any other beverages.
Dry Fasting Claims
Fans claim dry fasting benefits include aiding in weight loss, immune function, and cell regeneration, while reducing inflammation and delaying aging. But there isn’t enough research and data around dry fasting. Dry fasting can lead to dehydration, kidney issues, and cause other symptoms that aren’t worth the risk.
Dry Fasting Risks
Dry fasting is not recommended. While dehydration is one of the main risks - as you won’t be consuming water and other beverages - there are other potential symptoms, like:
- Fatigue.
- Irritability.
- Headaches.
- Lack of focus.
- Decreased urination.
- Constipation.
Dry fasting can also cause urinary, kidney, and lungs issues, as well as nutritional deficiencies and eating disorders.
Is Dry Fasting Effective for Weight Loss?
If you’re dehydrating yourself, you’re going to weigh less. This is true, but it’s water weight and not real body weight.
The risk of dry fasting is not worth the benefits - and those benefits aren’t clinically proven.
Can You Lose Weight Eating Bread?
Generally, when starting a weight loss diet the first thing most people do is quit eating bread. However, medical and nutrition specialists have revealed something really interesting: you can eat bread and lose weight at the same time, but you must include in your diet the healthiest type of bread.
According to what Dr. Gomez-Guillamon explains, all of us need two basic elements to live: oxygen and glucose. Glucose is essential for our brain. When we eat bread, our body retains half of this glucose. One part is converted to energy and the other part feeds the liver. Glucose is important for this organ because it helps it to carry out many of its functions, however, the problem arises when there is an “excess” of glucose.
Bread, for its part, does not make us gain fat. If we choose to do without bread in our diet, we will have less carbohydrates and less glucose. What does this mean? That, instead of losing fat, we will actually have less energy which will in turn reduce our muscle mass, the skin will become flaccid, we will suffer from constipation and we will have less glucose for the brain and liver.
Alternatives to the Bread and Water Diet
Given the risks associated with the bread and water diet, several healthier and more sustainable alternatives exist:
- Balanced Diet: Focus on consuming a variety of nutrient-dense foods, including fruits, vegetables, lean proteins, and whole grains. Aim for a calorie deficit through portion control and regular exercise.
- Intermittent Fasting: This involves cycling between periods of eating and fasting. Common methods include the 16/8 method (16 hours of fasting, 8 hours of eating) or alternate-day fasting.
- Mediterranean Diet: This diet emphasizes fruits, vegetables, whole grains, legumes, nuts, seeds, and olive oil. It has been linked to numerous health benefits, including weight loss and reduced risk of chronic diseases.
- Consult a Professional: Work with a registered dietitian or healthcare provider to develop a personalized eating plan that meets your individual needs and goals.
Prolonged Fasting and Its Effects
After seven days of fasting, the body undergoes a profound reset, switching energy sources, shedding fat, and activating unique protein changes linked to major organ health. Recent findings show that prolonged fasting triggers significant and systematic changes across multiple organs in the body. Researchers from Queen Mary University of London’s Precision Healthcare University Research Institute (PHURI) and the Norwegian School of Sports Sciences explored the potential health benefits of fasting, focusing on its underlying molecular mechanisms.
For thousands of years, humans have adapted to survive without food for extended durations. Today, fasting is widely practiced for both medical and cultural reasons, with goals ranging from improved health to weight loss. During fasting, the body changes its source and type of energy, switching from consumed calories to using its own fat stores. However, beyond this change in fuel sources, little is known about how the body responds to prolonged periods without food and any health impacts - beneficial or adverse - this may have.
Researchers followed 12 healthy volunteers taking part in a seven-day water-only fast. The volunteers were monitored closely on a daily basis to record changes in the levels of around 3,000 proteins in their blood before, during, and after the fast.
As expected, the researchers observed the body switching energy sources - from glucose to fat stored in the body - within the first two or three days of fasting. The volunteers lost an average of 5.7 kg of both fat mass and lean mass.
For the first time, the researchers observed the body undergoing distinct changes in protein levels after about three days of fasting - indicating a whole-body response to complete calorie restriction. Overall, one in three of the proteins measured changed significantly during fasting across all major organs.