Macronutrients simply explained: What protein, fat, and carbohydrates really do

What to expect in this article

What are macronutrients—and which ones are there?

Macronutrients are the nutrients the body takes in large amounts and from which it obtains energy. There are exactly three: protein, fat, and carbohydrates. They are measured in grams, not milligrams or micrograms.

The prefix “macro” describes precisely this difference in quantity. Micronutrients—that is, vitamins, minerals, and trace elements—are needed by the body in much smaller amounts, and they do not provide energy. They regulate metabolic processes rather than fueling them.

The three macronutrients do not perform the same function. Carbohydrates are the preferred source of energy, fat is the most energy-dense nutrient and also supplies essential fatty acids, while protein is primarily a building material for the body's own structures.

Source: German Nutrition Society (DGE), Reference Values for Nutrient Intake—Fat and Essential Fatty Acids, Carbohydrates, and Protein (protein: as of 2025)

These three figures are guidelines for the overall diet, not requirements for an individual meal. Two describe proportions of energy intake, while the third is an absolute value per kilogram of body weight—so the quantities are not directly comparable.

What about dietary fiber, water, and alcohol?

Dietary fiber is a subgroup of carbohydrates. It is not, or is barely, digested in the small intestine and therefore contributes little to energy supply, but it is still important for digestion.

Water is not counted among the macronutrients because it provides no energy. It is essential for life, but belongs in a separate category and therefore does not appear in macronutrient calculations.

Alcohol is the fourth energy-providing component of food. Nevertheless, it is not counted among the macronutrients because the body does not need it and has no function for it—it is primarily broken down rather than utilized.

Why does the body obtain energy from macronutrients?

The body uses energy around the clock—even during sleep. Macronutrients are the only source from which it can obtain this energy. How much is needed each day depends primarily on body size, body composition, and physical activity.

According to the Institute for Quality and Efficiency in Health Care (IQWiG, 2022), about 70% of calorie needs go toward resting energy expenditure, around 20% toward movement, and around 10% toward processing food itself. Most of the energy therefore goes into processes that take place without conscious effort.

In technical terms, this third block is called the thermic effect of food. In its FAQ on energy intake (as of 2025), the German Nutrition Society (DGE) puts it at approximately 10% of total energy expenditure. It is precisely within this tenth that the three macronutrients differ significantly.

How high is an adult's energy requirement?

The DGE's reference values for energy intake give the following guidelines for adults aged 25 to under 51 with a PAL value of 1.4 / 1.6 / 1.8: 2,300 / 2,700 / 3,000 kcal per day for men and 1,800 / 2,100 / 2,400 kcal per day for women. The PAL value describes physical activity throughout the day.

This range is why percentages are more useful for macronutrients than gram targets. The same 30% fat means something different at 1,800 kcal than at 3,000 kcal—namely, 540 kcal versus 900 kcal from fat.

This article deliberately focuses on terminology and fundamentals. Metabolism and Fat Burning explains how the body actually mobilizes and burns fat. Which methods measurably influence energy expenditure and which are merely claimed is assessed Boosting Metabolism Naturally. And anyone who wants to know what the difference between DNA and genes actually is can find the answer in The Difference Between DNA and Genes.

How do protein, fat, and carbohydrates differ?

The three macronutrients differ in four respects that matter in everyday life: the amount of energy they provide or their guideline value, their main function in the body, their thermic effect during digestion, and the foods that provide them.

The following overview compares them according to precisely these four criteria. All information comes from the sources listed in the references; values without reliable supporting evidence have deliberately not been included.

The table highlights a point that often gets overlooked in discussions: The DGE lists only fat and carbohydrates as a share of total energy. The protein reference value, by contrast, is based on body weight rather than calorie requirements.

Second point: The thermic effect differs by several times between macronutrients—according to Tappy (1996), cited in Mustafa et al. (2024), protein is at 20 to 30%, while fat is at 0 to 3%. However, this difference applies only within the approximately 10% of total energy expenditure that, according to the DGE (as of 2025), is attributable to food processing in the first place.

What does protein do in the body?

Protein is the body’s building material. Muscles, enzymes, hormones, antibodies, and connective tissue are made up of proteins, which the body continuously builds up and breaks down. Protein does provide energy as well, but that is not its primary role.

Proteins are made up of amino acids. The body can produce some of them itself, while others cannot be produced by the body and must be obtained through food. That is why, when it comes to protein, it is not only the quantity that matters but also the composition.

How much protein does the German Nutrition Society recommend?

According to the DGE (as of 2025), the reference value for adults aged 19 to 65 is 0.8 g of protein per kilogram of body weight per day. Mathematically, this corresponds to approximately 57 g per day for men and 48 g per day for women.

The value increases from age 65 onward. For this age group, the DGE gives an estimated value of 1.0 g per kilogram of body weight per day, corresponding to around 67 g for men and 57 g for women (DGE, as of 2025).

Regarding protein sources, the DGE writes: “Good sources of protein are meat, fish, dairy products and eggs, as well as legumes such as soy, lentils and peas, and grain products.” Adequate protein intake is therefore also possible without animal-based foods.

Do athletes need more protein?

For recreational athletes who are active for 30 minutes four to five times per week, the DGE (as of 2025) states that “an intake equal to the recommended intake of 0.8 g protein/kg of body weight per day” is sufficient. The reference value for adults therefore already covers this requirement.

The situation is different for ambitious athletes and competitive athletes who train for around five hours or more per week. For them, the DGE (as of 2025) recommends “a flexibly adjusted protein intake of approximately 1.2–2.0 g/kg of body weight per day,” explicitly citing the International Society of Sports Nutrition and the American College of Sports Medicine.

Protein also has the highest thermic effect of the three macronutrients: according to Tappy (1996), cited in Mustafa et al. (2024), 20 to 30% of the energy consumed is used for processing. For fat, the figure is 0 to 3%.

This difference is often used as an argument for weight loss. However, it applies only within the approximately 10% of total energy expenditure that, according to the DGE (as of 2025), is used for processing food—a fraction of one-tenth, and no more.

How much fat is beneficial—and which kind?

Fat is the macronutrient with the highest energy density. For adults aged 19 to 65, the DGE specifies a guideline value of 30% of total energy from fat. This makes fat the second-largest source of energy in a balanced mixed diet, after carbohydrates.

The DGE explains why this guideline value is lower than the one for carbohydrates by referring to energy density itself.

This higher energy density has a practical consequence: small amounts of fat affect the energy balance more than small amounts of carbohydrates or protein. This is the factual basis for the recommendation to limit fat intake.

Why not all fat is the same

Fat is the only macronutrient for which the DGE explicitly lists individual components as essential. For linoleic acid (omega-6), it specifies a guideline value of 2.5% of energy; for alpha-linolenic acid (omega-3), a guideline value of 0.5% of energy.

Essential means that the body cannot produce these fatty acids itself. A very low-fat diet can therefore not only reduce energy intake but also lower the intake of these two fatty acids.

Regarding quality, the DGE states verbatim: “Unsaturated fatty acids have predominantly positive effects on the body, such as lowering cholesterol levels and regulating blood pressure.” The type of fat is therefore just as relevant as the amount.

In practical terms, this means that within the 30% limit, it is worth considering where the fat comes from. Plant oils, nuts, and fatty sea fish provide predominantly unsaturated fatty acids.

How many carbohydrates does the body really need?

According to the DGE guidelines, carbohydrates are not the enemy of a healthy diet but its largest source of energy. The DGE states that “a balanced mixed diet should contain limited amounts of fat and more than 50% of energy intake in the form of carbohydrates.”

The reason for this high proportion lies in how the body works. The DGE states verbatim: “Carbohydrates are preferentially used by the body to produce energy.” They are therefore the standard fuel, not the reserve.

However, the source is crucial. The DGE explicitly names “whole-grain products, vegetables, fruit, legumes, and potatoes” as recommended sources of carbohydrates. In addition to energy, these foods provide fiber, vitamins, and minerals.

What the guideline value of more than 50% means in concrete terms

The guideline value is a proportion, not a gram amount. With an energy requirement of 2,100 kcal per day—the DGE guideline value for women aged 25 to under 51 with a PAL of 1.6—it therefore corresponds to more than 1,050 kcal from carbohydrates.

For a man in the same age group with a PAL of 1.6, the DGE guideline value is 2,700 kcal per day. More than 50% therefore means more than 1,350 kcal from carbohydrates—at the same percentage.

The thermic effect of carbohydrates lies between that of protein and fat: 5 to 10% of energy intake according to Tappy (1996), as cited by Mustafa et al. (2024). This difference is small for energy balance; for satiety, fiber content and degree of processing play a greater role.

Is there one correct macronutrient distribution?

No. There is no macronutrient distribution that is right for everyone—the DGE guideline values provide orientation for the population, not a formula for individual cases.

This is already evident from how the values are constructed. Fat and carbohydrates are given as a proportion of energy intake, whereas protein is given per kilogram of body weight. Anyone who forces all three into a single percentage scheme goes beyond the available evidence.

In addition, energy needs themselves vary considerably. According to the DGE reference values for adults aged 25 to under 51, the range resulting from sex and activity alone is between 1,800 and 3,000 kcal per day.

The following sequence shows how you can still find your bearings sensibly. It starts with total energy and only then distributes the individual macronutrients.

This order has a factual basis: Protein requirements are the only value that does not depend on calorie needs. They are therefore determined first, before fat and carbohydrates share the remaining energy.

The context remains important: Guidelines describe a target for average intake over a longer period. A single day on which the proportion of fat is higher or that of carbohydrates lower is not a medically significant deviation.

Nor can these reference values establish which distribution works best for weight loss. The DGE reference values describe a diet that meets nutritional needs—they are not dietary instructions and were not developed as such.

Which myths about macronutrients persist?

Three claims about macronutrients appear particularly often. All three can be examined against the published reference values of the German Nutrition Society—and all three fail to withstand this scrutiny.

The misconception behind this myth is the confusion between a nutrient and a food. Whole-grain bread and a soft drink both provide carbohydrates, but they differ fundamentally in fiber content, satiety, and energy density.

Essentiality is another factor. According to the DGE, linoleic acid should provide 2.5% and alpha-linolenic acid 0.5% of energy—both are fatty acids that the body cannot produce itself.

For recreational athletes, the DGE (as of 2025) explicitly states that “an intake equal to the recommended intake of 0.8 g of protein/kg of body weight per day” is sufficient. More protein is therefore not automatically an advantage, but initially simply more protein.

How mybody® can help with your nutrition strategy

The DGE reference values apply to the population as a whole. Anyone who wants to know which genetic predispositions are present in their own metabolism can use DNA analysis as an additional layer of information—as a supplement to the reference values, not a substitute.

mybody® (MYBODY Lab GmbH) offers a DNA test based on a saliva sample for this purpose. The analysis is performed in an ISO-certified laboratory, information security is certified according to ISO 27001, and data processing is GDPR-compliant.

NutriCare | INFINITY DNA Test

NutriCare | The INFINITY DNA test evaluates more than 140 genetic variations from a saliva sample and provides 54 analysis reports in 8 chapters across approximately 200 pages. The chapters include, among other things, nutrition and weight-loss strategy, metabolic type, well-being strategy, and sports type, as well as a food table containing more than 1,000 foods.

The test shows predispositions that do not change over the course of a person’s life. It provides no diagnosis, does not measure current nutrient status, and does not prescribe a macronutrient distribution that applies to everyone. The DGE reference values apply regardless of the test result.

Price: €269.00  ·  Sample type: saliva sample  ·  Processing time: approx. 20–25 business days after receipt of the sample  ·  Laboratory: ISO-certified laboratory analysis, ISO 27001, GDPR-compliant

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Price information as of July 28, 2026. Prices, report scope, and processing times may change—the linked mybody® (MYBODY Lab GmbH) product page is always authoritative.

The product connection can be substantiated in the “Metabolism type” chapter for four reports on metabolic-function traits: alcohol metabolism, caffeine metabolism, lactose metabolism, and gluten intolerance. These four topics concern the processing of individual food components—not how much fat, protein, or carbohydrates you should eat.

Putting it into context: What a DNA test can—and cannot—do

A DNA test answers a different question from “How much protein, fat, and carbohydrates should I eat?” It shows genetic predispositions. It neither measures current nutritional status or energy expenditure nor provides a diagnosis.

Genetic predisposition does not change either. A DNA result is therefore valid only once—in contrast to blood values, which reflect the current state and can shift with diet, the season, and life circumstances.

A genetic analysis likewise does not replace the reference values issued by professional societies. The DGE reference values of 30% of total energy from fat, more than 50% from carbohydrates, and 0.8 g of protein per kilogram of body weight per day apply regardless of what a test report indicates.

Finally, the following principle applies: No test replaces the fundamentals. If energy intake remains substantially above or below requirements over the long term, a saliva sample will not change that—regardless of which predispositions the report identifies.

Conclusion

Macronutrients are protein, fat, and carbohydrates—the three components of food from which the body obtains energy and with which it builds itself. Although alcohol also provides energy, it is not included because the body does not need it.

The evidence-based reference values are manageable: 30% of total energy from fat, more than 50% from carbohydrates, and 0.8 g of protein per kilogram of body weight per day for adults aged 19 to 65; from age 65 onward, 1.0 g per kilogram (DGE, as of 2025).

The limitation of these values is just as clear. They describe a diet that meets the needs of the population and are not an individual calculation formula—not least because fat and carbohydrates are given as a proportion of energy, while protein is given per kilogram of body weight.

In practical terms, this means: first assess your energy needs, base your protein intake on your body weight, keep your fat intake within the guideline range, and focus more on the source than the amount of carbohydrates.

If you would also like to know which predispositions are encoded in your genes, DNA analysis may be a possible next step—with the clear expectation that it reveals predispositions and does not determine a macro split.

Frequently asked questions about macronutrients

You might also be interested in

Sources

1. German Nutrition Society (DGE): Reference values for nutrient intake – Fat, essential fatty acids
2. German Nutrition Society (DGE): Reference values for nutrient intake – Carbohydrates
3. German Nutrition Society (DGE): Reference values for nutrient intake – Protein (as of 2025)
4. German Nutrition Society (DGE): Reference values for energy intake
5. German Nutrition Society (DGE): Energy intake FAQ (as of 2025)
6. Institute for Quality and Efficiency in Health Care (IQWiG): Causes of obesity (2022)

The guideline value of 30 % of total energy from fat, the figures for linoleic acid and alpha-linolenic acid, and the verbatim institute quotation are based on [1]. The carbohydrate guideline value of more than 50 % of energy intake and the carbohydrate sources cited come from [2], while the protein reference values, including the range for athletes, come from [3]. The guideline values for energy intake and the PAL values come from [4], the figure of approximately 10 % for the thermic effect of food comes from [5], and the breakdown into resting energy expenditure, activity energy expenditure, and food processing comes from [6]. The macronutrient-specific values for the thermic effect are identified in the text at the relevant point as “according to Tappy (1996), cited in Mustafa et al. (2024)”; all other studies mentioned in the text are likewise attributed in each relevant location with authorship and year and can be found there. All product information for mybody® (MYBODY Lab GmbH) comes from the official product pages at mybody-x.com, as of July 28, 2026.

mybody® Editorial & Expert Team

Macronutrients Nutritional science Energy metabolism Nutrigenetics Laboratory diagnostics

This article was created and medically reviewed by the mybody® editorial and expert team at MYBODY Lab GmbH. The team combines expertise in nutritional science, laboratory diagnostics, blood analysis interpretation, microbiome research, and nutrigenetics. Learn more about the people behind it on the mybody® authors' page.

Published on July 28, 2026 · Last updated on July 28, 2026

Medical notice: This article is for general information only and does not replace medical advice, diagnosis, or treatment. DNA tests and self-tests provide indications, not diagnoses. If you experience unintended weight loss, persistent fatigue, or other unexplained symptoms, please consult a doctor. If you take medication, are pregnant, or are breastfeeding, discuss significant dietary changes with a doctor beforehand.