Egg calories and nutritional value explained

Most of an egg’s calories come from the yolk, but eggs offer more than just energy. Here you’ll find a simple overview of what’s in the white and the yolk, and why an ordinary hen’s egg is so rich in nutrients.

Egg calories: why are eggs so nutritious?

An egg is among the most complete foods for a living organism because it provides the foundation for a chick’s development. This also explains why eggs contain protein, fats, vitamins, minerals and other compounds that the body can readily use.

When discussing egg kcal or egg calories, it helps to look at the egg’s 2 main parts separately. The white is the almost fat-free, protein-based part. The yolk provides most of the energy, fat and fat-soluble vitamins.

A whole egg combines both. According to the original data, the yolk accounts for 30.4% and the white for 69.6%. Together, they make a food that is small, inexpensive and highly versatile in everyday cooking.

Egg whites: protein with little fat

Egg white contains 10.1% protein, which accounts for 89% of its energy. This is why egg whites have long been valued by people who train and those on a diet. An egg’s protein content isn’t just about grams; its amino acid composition matters too.

The carbohydrate share of egg white’s energy is smaller, at 11%. When dried egg white is produced, most of the carbohydrates (glucose) are removed before drying, using bacteria, enzymes or yeast. The reason is simple: this reduces the risk of the Maillard reaction, which can turn the product brown and make it less soluble.

Ordinary egg white contains practically no fat. If an egg is stored for a long time, a little fat may migrate from the yolk into the white. A small amount of yolk can also get into the white when an egg is cracked and separated. This amount is usually insignificant for health.

An important point concerns avidin. Egg white contains 0.05% avidin protein, which, according to the book The Avian Egg, can be problematic if raw eggs or egg whites are eaten in large quantities. Boiling helps reduce this risk.

Egg yolks and egg calories

The yolk is the more energy-rich part of an egg. Overall, it contains 77% of the egg’s total energy. It contains fatty acids, cholesterol, lecithin, cephalin, vitamins A, E, K and D, and many minerals.

The fatty acids in egg yolk include linoleic acid. This is a polyunsaturated fatty acid that the human body cannot produce. Egg yolk also contains cholesterol, which has been the subject of much debate over the years.

The original text states that egg yolk theoretically contains around 1500 mg of cholesterol per 100 g of yolk, accounting for 4.5% of the yolk’s fat. A later table also lists 1700 mg/100 g, corresponding to 3.3% of the fat content. These figures show why egg yolks deserve consideration beyond calories alone.

The simple truth is that eggs are neither entirely “good” nor entirely “bad”. For most people, eggs fit well into a normal, varied diet. If your doctor has recommended restrictions because of cholesterol, you should follow that advice.

Egg nutritional value in numbers

The average composition of a hen’s egg, according to Egg Science and Technology (1990) and the Sanovo Foods laboratory:

Egg weight 60 g
Shell 9.5 %
White 63.0 %
Yolk 27.5 %

According to the Danish National Food Agency, the composition of an egg’s contents per 100 g is as follows:

Whole egg: water 74.6 g, protein 12.1 g, fat 11.2 g, carbohydrates 1.2 g, ash 0.9 g
Egg white: water 88.1 g, protein 10.1 g, fat 0.0 g, carbohydrates 1.2 g, ash 0.6 g
Egg yolk: water 48.8 g, protein 16.4 g, fat 32.9 g, carbohydrates 0.2 g, ash 0.7 g

The eggshell is less relevant when considering the edible portion, but its structure is interesting. Inside the shell are 2 membranes: an outer membrane measuring 48 micrometers and an inner membrane measuring 22 micrometers. The shell consists of 98.2% calcium, 0.9% magnesium and 0.9% phosphorus. The water-repellent film on its surface measures 1030 micrometers.

The proteins in egg white include ovalbumin 54, ovotransferrin 12, ovomucoid 11, ovomucin 3.5, lysozyme (G1 globulin) 3.4, G2-globulin 4.0?, G3-globulin 4.0?, ovoinhibitor 1.5, ficin inhibitor 0.05, ovoglycoprotein 0.8, ovomacroglobulin 0.5 and avidin 0.05.

The chemical composition of egg yolk is: protein 16.4%, fat 32.93%, carbohydrates 0.2%, ash or minerals 1.7%, and water 48.8%. Egg yolk contains lecithin at 7.2/100 g, which helps form emulsions of fat and water. This is why egg yolk is used in mayonnaise, salad dressings and similar foods.

The theoretical composition of a whole egg is: protein 12.4%, fat 11.15%, carbohydrates 1.20%, ash or minerals 0.90%, and water 74.60%. These figures help you better understand where the kcal in 1 egg come from and why eggs provide both protein and fat.

How can you use eggs in the kitchen?

Eggs work well in breakfasts, baked goods, sauces and salads. Whole eggs thicken sauces, help baked goods rise and act as an emulsifier. This is also why eggs are indispensable in so many recipes.

If your goal is more protein and less energy, using more egg whites is sometimes an option. If you want to feel full and get micronutrients, you shouldn’t automatically discard the yolk. Frankly, much of an egg’s nutritional value is in the yolk.

FAQ: egg calories and nutritional value

Do most of an egg’s calories come from the yolk?

Yes. The yolk contains most of an egg’s energy because it contains the fat. The white mainly provides protein and typically contains 0.0 g of fat.

Is eating a lot of raw egg whites a good idea?

It’s best not to. The original source notes an avidin content of 0.05% and a potential risk when large amounts are consumed. Boiling or another form of cooking is a more practical choice.

Is a darker egg yolk richer in vitamins?

Not necessarily. The yolk gets its color from carotenoids and pigments in the feed. A darker color does not automatically mean a higher vitamin content.

Sources

Egg Science and Technology (1990); Sanovo Foods laboratory; Poul Erner Andersen, Introduktion til levnedsmiddelsteknologien; The Avian Egg.

Ask our nutrition counselor for advice! ArtGym

Author: Compiled by M.M.

Source: WHO – healthy eating.

Source: WHO – healthy eating.