Fasting is a common tradition that involves abstaining from or restricting food consumption. It has been practiced for thousands of years for both religious and health reasons.

In recent years, fasting has become a popular way for people to lose weight.

An egg fast is a short-term diet plan that involves eating mainly eggs, cheese, and butter.

It’s popular among people who seek to break through weight loss plateaus, especially those on ketogenic diets.

This article explains what an egg fast is, including its rules, benefits, and risks.

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An egg fast is a short-term diet plan developed by blogger Jimmy Moore in 2010.

It’s a restricted ketogenic diet — a way of eating that’s high in fat, moderate in protein, and low in carbs.

Ketogenic diets help your body enter the metabolic state of ketosis, during which it starts using ketones as a source of energy instead of glucose (1).

The purpose of an egg fast is to help you bust through weight loss plateaus. These are discouraging points in a weight loss plan where your fat loss stalls.

Some people use it to help their body enter ketosis — before beginning a ketogenic diet.

The plan has many rules, including:

  • Whole eggs — yolks and whites — are the main source of fat and protein.
  • You must consume 1 tablespoon (15 grams) of butter or healthy fat per egg consumed.
  • You must eat a whole egg within 30 minutes of waking up.
  • You must eat an egg-based meal every three to five hours.
  • You must eat a meal even if you’re not hungry.
  • You can eat up to 1 ounce (28 grams) of full-fat cheese per egg consumed.
  • You must eat at least six whole eggs per day.
  • Eggs should be local, pastured eggs whenever possible.
  • You should stop eating three hours before bedtime.
  • You can drink up to three cans of diet soda per day but aim for one or less.

These are the most common rules, but people tend to make their own modifications.

A typical egg fast lasts between three to five days as this should be enough to overcome a weight loss plateau.

Following it longer than this is not recommended, as it may lead to health risks, such as nutritional deficiencies and constipation.

The egg fast is unsuitable for people with certain medical conditions like diabetes, eating disorders, cholesterol hyper-responders, and people without a gallbladder.

It’s also inappropriate for people who cannot eat eggs, such as vegans, those with egg allergies, or those who avoid eggs for religious reasons.

Summary An egg fast is a short-term ketogenic diet that involves eating primarily whole eggs and sources of fat, such as butter and cheese.

An egg fast works by inducing the metabolic state of ketosis.

Ketosis occurs when your body has little access to glucose, its preferred fuel source. To compensate, your body makes ketone bodies out of fat and uses them as fuel (1).

To reach ketosis, people typically need to eat 50 grams of carbs or less per day. They get the rest of their calories from a high-fat, moderate-protein diet.

A ketogenic diet can aid weight loss by promoting feelings of fullness, restricting food options, increasing protein intake, and potentially decreasing fat storage (2, 3, 4).

What’s more, some studies find that ketogenic diets may promote more weight loss than conventional low-fat, low-calorie diets (5, 6).

However, an egg fast only lasts three to five days, so it may not be enough time for someone to reach ketosis. In some cases, it make take a week or longer to enter this state.

The diet plan is more restrictive than conventional ketogenic diets, as it reduces the number of food items you can eat. This restriction can slash your calorie intake and further promote weight loss.

Though an egg fast will help you lose weight, your overall results depend on several factors, such as your starting weight, height, age, gender, and total food intake.

For instance, someone with a higher starting weight should expect to lose more fat than someone at a lower starting weight.

That said, most people claim they lose 5–10 pounds (1.4–2.7 kg) in 3–5 days.

Summary An egg fast can help you lose weight by restricting calories and promoting ketosis — a metabolic state in which your body uses ketones as a source of fuel.

To date, the egg fast has not been scientifically studied.

The following benefits are what you may expect from following a short-term, restricted ketogenic diet that encourages eating eggs.

Keep in mind that an egg fast only lasts three to five days, so you may not get the full benefits of a conventional ketogenic diet.

Here are some benefits you may expect:

May Reduce Appetite

An egg fast encourages eating eggs, which are known to be very filling (7).

In fact, numerous studies show that eating eggs can help you feel fuller for longer. That can lead to consuming fewer calories per day and will likely promote weight loss (8, 9, 10).

Eggs are filling because they’re high in protein.

Research indicates that a high protein intake may help raise levels of hormones that promote fullness, such as peptide YY (PYY), GLP-1, and CCK, while reducing levels of the hunger-promoting hormone ghrelin (11, 12).

Aside from being high in protein, an egg fast is a type of ketogenic diet, which some studies have found to be more filling than standard low-fat, low-calorie diets (2).

Can Help You Lose Weight

An egg fast is a very restrictive, short-term diet that limits your food options.

Research indicates that limiting the number and variety of approved foods naturally reduces your daily calorie intake (13).

The diet plan is also based on ketogenic principles, which may promote ketosis.

Studies show that ketogenic diets can help you lose fat, maintain muscle mass, curb appetite, and improve markers of disease, such as high blood sugar, triglyceride, and cholesterol levels (2, 14, 15, 16).

However, an egg fast only lasts three to five days, which may not be enough time for you to reach ketosis. In some cases, it may take a week or longer to reach this state.

May Promote Belly Fat Loss

Belly fat, or visceral fat, is a risk factor for heart disease, diabetes, and other chronic conditions.

Ketogenic diets like the egg fast may help you burn more belly fat than low-fat diets.

In one study, adults following a ketogenic diet lost more total fat and belly fat than those on a low-fat diet — despite eating 300 more calories per day (6).

In a 12-week study, women who followed a ketogenic diet lost an average of 21.2% of visceral fat — compared to a 4.6% reduction in women on a high-fiber, low-fat diet (17).

Still, as an egg fast only lasts a few days, it's unclear how much belly fat you would lose.

May Reduce Insulin Resistance

Insulin resistance occurs when your body does not respond properly to insulin, a hormone that regulates blood sugar.

Several studies show that ketogenic diets may reduce insulin resistance, which in turn can improve your body's ability to manage blood sugar levels.

In a small, 2-week study, people with type 2 diabetes who followed a ketogenic diet reduced their insulin resistance by 75% (18).

In other studies, participants with type 2 diabetes on a ketogenic diet were able to either reduce or completely stop taking their diabetes medication (19, 20).

Though following an egg fast may temporarily reduce insulin resistance, long-term changes must be made to promote continued results. If you have type 1 or type 2 diabetes, speak with your healthcare provider before attempting an egg fast, as it could be dangerous.

Summary An egg fast may offer similar benefits as conventional ketogenic diets, including weight and belly fat loss, as well as reduced appetite and insulin resistance. Still, research on egg fasting specifically is unavailable.

An egg fast comes with a few potential side effects for healthy adults.

If you’re new to ketogenic diets, you may experience the keto flu, which is caused by your body adapting to ketones as a source of energy instead of glucose (21).

Common symptoms include increased hunger, irritability, low energy, sleep issues, nausea, poor mental function, weakness, headaches, and bad breath (21).

Most of these symptoms are temporary and should disappear after a few days of fasting. To reduce your risk of the keto flu, try following a low-carb diet before you begin an egg fast.

Constipation is another possible side effect, as the diet restricts high-fiber foods like vegetables and fruits (22).

To reduce this risk, try drinking as much water as possible.

An egg fast is also a short-term diet and should not last longer than three to five days. That’s because it restricts many healthy food groups that are necessary for optimal health.

Following this diet for too long may increase your risk of a nutritional deficiency. If you fast regularly, consider taking a multivitamin to help you meet your nutritional needs.

Though an egg fast can promote fast weight loss, you will likely regain the weight when you return to your regular diet — unless you implement long-term weight maintenance strategies.

An egg fast is unsuitable for people with type 1 or type 2 diabetes, cholesterol hyper-responders, people with eating disorders, and those without a gallbladder — unless supervised by a medical professional.

Additionally, egg fasts — along with other types of fasting — are inappropriate for pregnant or breastfeeding women.

If you have any medical conditions, speak to your healthcare provider before starting any fast.

Summary For a healthy adult, an egg fast comes with a few — but mostly temporary — potential side effects. Don’t follow this diet for longer than five days, as it puts you at risk for nutritional deficiencies. This diet may be inappropriate for some people.

The following menu gives you insight into what an egg fast looks like.

Day One

  • Breakfast: an egg-cheese omelet made with 2–3 eggs, cooked in 2–3 tablespoons (30–45 grams) of butter or another healthy oil, such as olive oil
  • Snack: 1 stick of string cheese
  • Lunch: 2–3 deviled eggs
  • Snack: 2 ounces (57 grams) of a cheese of your choice
  • Dinner: egg crepe made using just 2–3 eggs, cooked in 2–3 tablespoons (30–45 grams) of butter or another healthy oil, such as olive oil

Day Two

  • Breakfast: cream cheese pancake — 2–3 eggs and 2–3 tablespoons (30–45 grams) of cream cheese blended until smooth and cooked on a pan or griddle with 3 tablespoons (45 grams) of butter
  • Snack: 1 ounce (28 grams) of a cheese of your choice
  • Lunch: egg salad — 2 eggs and 2 tablespoons (30 grams) of mayonnaise
  • Snack: 1 ounce (28 grams) of a cheese of your choice
  • Dinner: crustless cheese quiche made with 2 eggs

Day Three

  • Breakfast: 2 eggs fried in 2 tablespoons (30 grams) of butter with a cup of tea or black coffee
  • Snack: 2 sticks of string cheese
  • Lunch: leftover slice of crustless cheese quiche
  • Snack: 1 ounce (28 grams) of a cheese of your choice
  • Dinner: 2–3 deviled eggs

Day Four

  • Breakfast: egg and cheese omelet made with 2–3 eggs, cooked in 2–3 tablespoons (30–45 grams) of butter
  • Snack: 1 ounce (28 grams) of a cheese of your choice
  • Lunch: 2 hard-boiled eggs
  • Snack: 2 sticks of string cheese
  • Dinner: 2 egg waffles — 2–3 eggs cooked in a waffle maker with butter

Day Five

  • Breakfast: 3 eggs scrambled with a cup of tea or black coffee
  • Snack: 1 stick of string cheese
  • Lunch: egg salad — 2 eggs and 2 tablespoons (30 grams) of mayonnaise
  • Snack: 1 ounce (28 grams) of a cheese of your choice
  • Dinner: crustless cheese quiche
Summary The five-day egg fast consists of eating eggs, cheese, and sources of fat, such as butter or oil.

An egg fast is a short-term, restrictive ketogenic diet that includes mainly eggs, cheese, and butter or another fat source.

It lasts three to five days and may aid short-term weight loss. Still, it may have potential risks like nutritional deficiencies — particularly if you follow it for longer than advised.

Though an egg fast may help you break a weight loss plateau, it’s not a long-term solution. Try following a healthy, well-balanced diet for lasting results.