What is fat?

Fat is one of the three main nutrients (macronutrients), along with carbohydrates and protein. It serves as the body's most concentrated source of energy and is essential for numerous vital functions. Fat provides 9 kcal (37 kJ) per gram—more than twice as much energy as carbohydrates or proteins.

But fat is much more than just a source of energy: it plays a crucial role in cell structure, hormone production, nutrient absorption, and temperature regulation. Without fat, a healthy metabolism, a strong immune system, and a functioning nervous system would not be possible.

Types of fats

Not all fats are the same—they differ in their chemical structure and effects on health.

1. Saturated fatty acids:

  • Found mainly in animal products (butter, meat, milk), as well as coconut and palm fats.

  • Solid at room temperature.

  • Serve as an energy reserve and protective layer for organs, but should be consumed in moderation, as excessive intake has been linked to elevated cholesterol levels.

2. Monounsaturated fatty acids:

  • Found, for example, in olive oil, avocados, nuts, and rapeseed oil.

  • Support cardiovascular health, help lower LDL cholesterol (“bad cholesterol”), and promote the absorption of fat-soluble vitamins.

3. Polyunsaturated fatty acids:

  • Include omega-3 and omega-6 fatty acids, which are essential—the body cannot produce them itself.

  • Sources: fatty fish (salmon, mackerel, herring), walnuts, flaxseeds, chia seeds, sunflower oil.

  • They support the heart, brain, eyes, and regulation of inflammation.

4. Trans fatty acids:

  • Formed by the industrial hydrogenation of oils or by heating them at high temperatures.

  • Found mainly in processed foods, baked goods, and frying fats.

  • Should be avoided entirely, as they promote cardiovascular disease.

Functions of fat in the body

1. Energy source and energy store:
Fat is the body's most important energy store. It is stored in fat cells (adipocytes) and mobilized to produce energy when needed, especially during prolonged physical activity or food shortages.

2. Cell structure and protection:
Fats are a major component of cell membranes and provide stability, elasticity, and permeability. Fat tissue also protects internal organs from impact and cold.

3. Hormone production:
Fats are the building blocks for important hormones and signaling molecules (e.g., steroid hormones such as estrogen and testosterone, as well as prostaglandins).

4. Absorption of fat-soluble vitamins:
The body can only absorb, store, and utilize vitamins A, D, E, and K with the help of fat.

5. Brain and nervous system:
The brain is largely made up of fat. In particular, omega-3 fatty acids (e.g., DHA) are crucial for the development and function of the brain and nerves.

Benefits of a balanced fat intake

  • Provides lasting energy

  • Supports hormonal balance and fertility

  • Promotes the absorption of essential vitamins

  • Protects organs and cells

  • Supports skin, hair, and brain

  • Strengthens the cardiovascular system (when fat quality is right)

Recommended fat intake

According to the German Nutrition Society (DGE), about 30–35% of daily energy intake should come from fat. The following applies:

  • Saturated fats: < 10% of total energy

  • Unsaturated fats (especially omega-3): prioritize

  • Trans fats: avoid as much as possible

For example, with an energy requirement of 2,000 kcal, about 65–75 g of fat per day should be consumed.

Possible consequences of deficiency or excess

Fat deficiency:

  • Dry skin, brittle hair

  • Hormonal disorders

  • Difficulty concentrating

  • Deficiency of fat-soluble vitamins (A, D, E, K)

Excessive fat intake (especially saturated and trans fats):

  • Elevated blood lipids and cholesterol

  • Overweight

  • Increased risk of cardiovascular disease

Conclusion

Fat is essential to life – it provides the body with energy, protects organs, regulates hormones, and supports the absorption of important vitamins. However, the quality of the fats consumed is crucial: healthy unsaturated fatty acids (e.g., from olive oil, nuts, and fish) should make up most of the fat intake, while saturated fats and especially trans fats should be reduced as much as possible. A mindful balance of fats is therefore the foundation for health, performance, and well-being.

Sources

  1. German Nutrition Society (DGE). (2020): Fat intake and fatty acids – DGE recommendations.

  2. Mensink RP, et al. (2016): Effects of saturated, monounsaturated, and polyunsaturated fatty acids on serum lipids and lipoproteins. Am J Clin Nutr, 103(3), 708–718.

  3. Calder PC. (2015): Functional roles of fatty acids and their effects on human health. J Parenter Enteral Nutr, 39(1), 18S–32S.

  4. Mozaffarian D, Katan MB, Ascherio A, Stampfer MJ, Willett WC. (2006): Trans fatty acids and cardiovascular disease. N Engl J Med, 354(15), 1601–1613.