What is fat?

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

But fat is far more than just an energy source: it plays a crucial role in cell structure, hormone production, nutrient absorption, and thermoregulation . 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 effect on health.

1. Saturated fatty acids:

  • They are found primarily in animal products (butter, meat, milk) as well as in coconut and palm oil.

  • They are solid at room temperature.

  • They serve as an energy reserve and protective layer for organs, but should be consumed in moderation , as excessive consumption is associated with increased cholesterol levels.

2. Monounsaturated fatty acids:

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

  • They support cardiovascular health , help lower LDL cholesterol ("bad cholesterol") and promote the absorption of fat-soluble vitamins.

3. Polyunsaturated fatty acids:

  • They include the 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 inflammation regulation .

4. Trans fatty acids:

  • They are formed by the industrial hardening of oils or by intense heating.

  • They are found primarily in convenience foods, baked goods, or frying fats.

  • They should be strictly avoided , as they promote cardiovascular diseases.

Functions of fat in the body

1. Energy source and energy storage:
Fat is the body's most important energy reserve . It is stored in fat cells (adipocytes) and mobilized for energy production when needed – especially during prolonged physical activity or food shortages.

2. Cell structure and protection:
Fats are a major component of cell membranes , providing stability, elasticity, and permeability. Furthermore, adipose tissue protects internal organs from impacts and cold.

3. Hormone production:
Fats are starting materials for the formation of important hormones and messenger substances (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 through fat.

5. Brain and nervous system:
The brain consists largely of fat. Omega-3 fatty acids (e.g., DHA) are particularly crucial for the development and function of the brain and nerves.

Benefits of a balanced fat intake

  • Provides long-lasting energy

  • Supports hormone balance and fertility

  • Promotes the absorption of vital vitamins

  • Protects organs and cells

  • Supports skin, hair and brain

  • Strengthens the cardiovascular system (with the right quality of fat)

Recommended fat intake

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

  • Saturated fats: < 10% of total energy

  • Unsaturated fats (especially Omega-3): prefer

  • Trans fats: avoid as much as possible

For example: With an energy requirement of 2000 kcal, approximately 65–75 g of fat should be consumed per day .

Possible consequences of deficiency or excess

Fat deficiency:

  • Dry skin, brittle hair

  • Hormonal imbalances

  • Concentration problems

  • 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 for 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 the majority of fat intake, while saturated and especially trans fats should be reduced as much as possible. A conscious fat balance is therefore fundamental to 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.