Two Vital Ways the Fats We Eat Help Us Function

November 18, 2025 •

3 min read

According to the National Institutes of Health, fats provide more than double the calories per gram compared to protein or carbohydrates, making them our most concentrated energy source. This energy is vital, but the fats we eat help us in two additional, crucial ways: aiding vitamin absorption and serving as building blocks for cellular health. Understanding these lesser-known functions is key to appreciating the role of fat in a balanced diet.

Quick Summary

Fats are essential for health, providing energy and helping our bodies absorb fat-soluble vitamins like A, D, E, and K. They also serve as vital structural components for cell membranes and nerve sheaths. Healthy fats from sources like olive oil, nuts, and fish are necessary for overall physiological well-being.

Key Points

Energy Source: Dietary fats are the body's most concentrated source of energy, providing 9 calories per gram and acting as a long-term fuel reserve.
Vitamin Absorption: Healthy fats are essential for the proper absorption and utilization of fat-soluble vitamins (A, D, E, and K), which are vital for vision, bone health, and immune function.
Cellular Building Blocks: Fats are a fundamental component of cell membranes, providing structure and flexibility for every cell in your body.
Organ Protection: The body stores fat to insulate and protect vital organs from shock and physical damage.
Nervous System Health: The myelin sheath that insulates nerve cells is made of fat, facilitating the efficient transmission of nerve signals.
Satiety and Flavor: Eating fat helps you feel full and satisfied after a meal, preventing overeating, and also enhances the flavor of food.

Providing Energy and Absorbing Essential Vitamins

The Body's Most Concentrated Fuel Source

Dietary fat is the most energy-dense macronutrient, containing 9 calories per gram compared to the 4 calories per gram found in protein and carbohydrates. This means fats provide a sustained, long-term energy reserve, which was critical for human survival through periods of food scarcity. While carbohydrates provide quick energy, fat provides a larger, more compact fuel storage system for the body's ongoing needs, including fueling muscles during prolonged exercise after initial carbohydrate stores are depleted. The stored energy in adipose tissue is essential for meeting the body's daily energy demands, even when at rest.

Aiding the Absorption of Fat-Soluble Vitamins

One of the most important functions of the fats we eat is their role in absorbing fat-soluble vitamins—Vitamins A, D, E, and K. These vitamins are crucial for many bodily functions, but they cannot be properly absorbed and transported without the presence of dietary fat.

Vitamin A: Essential for vision, immune function, and cell growth.
Vitamin D: Critical for bone health, regulating calcium and phosphorus levels.
Vitamin E: Acts as an antioxidant, protecting cells from damage.
Vitamin K: Necessary for blood clotting and bone metabolism.

This is why eating fat-rich foods like nuts, seeds, avocados, and oily fish is a highly efficient way to get these vital nutrients into your system. For example, cooking vegetables with a healthy oil can significantly increase the bioavailability of their fat-soluble vitamins.

Building and Protecting the Body's Structures

Building Healthy Cells

Fats, particularly essential fatty acids like omega-3s and omega-6s, are crucial structural components of the body. They are used to build the membranes that surround every cell, defining its exterior and controlling what enters and exits. The fluidity and integrity of these cell membranes are directly influenced by the types of fats consumed, which in turn impacts cell function. For instance, healthy unsaturated fats contribute to more flexible cell membranes, which is critical for proper cellular communication and the transport of nutrients.

Protecting Organs and Nerves

Beyond cellular structure, fat serves as a vital protective layer for the body's organs. Visceral fat, located within the abdominal cavity, provides cushioning for organs like the heart, kidneys, and liver. Additionally, a layer of subcutaneous fat beneath the skin provides insulation, helping to maintain body temperature. The nervous system also relies heavily on fat, as nerve cells are insulated by a protective sheath called myelin, which is primarily composed of fat. This myelin sheath facilitates the rapid transmission of nerve signals throughout the body.

Comparing Healthy vs. Unhealthy Fats


Feature	Unsaturated Fats (Healthy)	Saturated & Trans Fats (Less Healthy)
Sources	Plant oils (olive, canola), avocados, nuts, seeds, oily fish	Red meat, butter, whole milk, some processed foods
Cholesterol Impact	Can lower LDL (bad) cholesterol and raise HDL (good) cholesterol	Can raise LDL (bad) cholesterol, increasing heart disease risk
State at Room Temp	Tend to be liquid (oils)	Tend to be solid (butter, shortening)
Primary Function	Supports cell structure, provides essential fatty acids	Provides energy, but excessive intake is linked to health issues

Conclusion: Incorporating Healthy Fats into Your Diet

Instead of viewing fat as a dietary foe, it's more accurate to see it as a necessary nutrient that performs critical functions within the body. The two primary ways the fats we eat help us—providing concentrated energy and facilitating vitamin absorption—are complemented by their role as fundamental building blocks for healthy cells and protective layers for our organs and nerves. By focusing on incorporating healthy, unsaturated fats from sources like fish, nuts, and avocados while limiting less healthy saturated and trans fats, you can reap the essential benefits that dietary fat provides. This balanced approach supports overall health, from energy production to cellular integrity, proving that the right kind of fat is your body's friend.

For more detailed nutritional guidelines, consider visiting the American Heart Association website.

Frequently Asked Questions

Saturated fats are typically solid at room temperature and found in animal products like butter and red meat, while unsaturated fats are usually liquid and found in plant-based sources like olive oil, nuts, and fish. Unsaturated fats are generally considered healthier for heart health.

Fats help your body absorb fat-soluble vitamins (A, D, E, and K). These vitamins cannot be properly absorbed and transported by the body without the presence of dietary fat. Including healthy fats in your meals is key to getting the full benefit of these nutrients.

The best sources of healthy, unsaturated fats include avocados, nuts (almonds, walnuts), seeds (flaxseeds, chia seeds), fatty fish (salmon, mackerel), and plant-based oils (olive, canola).

Yes, a diet that is excessively low in fat can be unhealthy. The body needs some fat to function correctly, particularly for absorbing fat-soluble vitamins and providing essential fatty acids. A diet too low in fat can lead to nutritional deficiencies.

Yes, all dietary fats provide the same amount of energy per gram, which is 9 calories. However, the type of fat (e.g., saturated vs. unsaturated) affects its impact on your overall health, cholesterol levels, and risk of certain diseases.

Fats are crucial for brain health. The brain is rich in fat and relies on it for structural integrity. Essential fatty acids, particularly omega-3s, are needed for nerve cell membranes and facilitate the efficient transmission of nerve impulses.

While recommendations vary, health experts generally suggest that 20% to 35% of your daily calories should come from fat. The focus should be on prioritizing healthy unsaturated fats over less healthy saturated and trans fats.