Why Your Body Needs Dietary Fat

The human body requires dietary fat to survive, as it serves as a structural component of all cell membranes and provides 20% to 35% of an adult's daily energy requirements under Australian National Health and Medical Research Council guidelines.

Why does your body need dietary fat?

Dietary fats are an essential part of your eating pattern and are important for maintaining your overall physiological health, according to Healthdirect Australia. They serve as a concentrated source of energy, delivering 37 kilojoules per gram, which is more than double the energy provided by carbohydrates or proteins.

At a microscopic level, lipids function as a structural and functional component of all cell membranes in the human body, as detailed in a study published in PMC6628852. Without these lipids, your cells could not maintain their integrity or communicate effectively.

On a systemic level, Harvard Health Publishing notes that dietary fat provides essential insulation to keep you warm, protects vital internal organs from physical damage, and supports healthy cell growth. Consuming adequate dietary fat also plays a key role in keeping cholesterol levels and blood pressure under control, helping your cardiovascular system function smoothly.

How does fat help with nutrient absorption?

Your body relies on dietary fat to utilise several essential nutrients. The Better Health Channel states that dietary fat is essential for transporting specific fat-soluble vitamins throughout the bloodstream to where they are needed.

Specifically, Healthdirect Australia confirms that your body cannot absorb essential fat-soluble vitamins A, D, E, and K without adequate dietary fat intake. Vitamin A is vital for vision, vitamin D supports bone health, vitamin E acts as an antioxidant, and vitamin K is crucial for blood clotting.

Consuming healthy fats alongside vegetables helps your body utilise these fat-soluble nutrients and antioxidants more efficiently, according to Mayo Clinic research. For example, adding a drizzle of Australian cold-pressed extra virgin olive oil to a leafy green salad significantly increases the absorption of carotenoids and other fat-soluble vitamins present in the vegetables.

What is the link between dietary fat and hormones?

Dietary fat plays a direct, supportive role in the production of essential hormones in the human body, as highlighted by the Better Health Channel. Cholesterol, which is a type of lipid, serves as the primary building block for steroid hormones, including estrogen, progesterone, and testosterone.

Research published in PMC5577766 shows that essential fatty acids like linoleic acid and alpha-linolenic acid, which the human body cannot synthesise, must be consumed to maintain normal endocrine function. These essential fatty acids act as precursors for eicosanoids, which are signaling molecules that regulate inflammation and blood pressure.

Furthermore, very-long-chain omega-3 fatty acids, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are critical for normal brain development and regulating systemic inflammatory hormone pathways, according to PMC5577766. These fatty acids are highly concentrated in brain tissue and support cognitive health throughout life.

Additionally, clinical studies have shown that total dietary fat and polyunsaturated fatty acid intake are associated with very small increases in testosterone concentrations in healthy premenopausal women, as documented in PMC4763493. Meanwhile, a high intake of dietary fat is associated with higher serum levels of estrone and dehydroepiandrosterone sulfate (DHEAS) in postmenopausal women, according to research in ScienceDirect.

Unsaturated versus saturated fat: what is the difference?

Not all fats affect the body in the same way. Dietitians Australia explains that replacing foods high in saturated fats with unsaturated fats helps lower blood cholesterol levels and supports cardiovascular health. Unsaturated fats, which are liquid at room temperature, are considered beneficial fats because they improve blood cholesterol profiles.

In contrast, the Australian Dietary Guidelines warn that saturated fats can increase the risk of heart disease by raising harmful LDL cholesterol levels in the blood. Saturated fats are typically solid at room temperature and are commonly found in fatty cuts of meat, butter, and processed foods.

Trans fats are particularly harmful because they simultaneously raise 'bad' LDL cholesterol and lower 'good' HDL cholesterol, according to the National Heart Foundation of Australia. The Australian Dietary Guidelines recommend avoiding trans fats entirely, which are often found in deep-fried foods and commercial baked goods.

What are the best sources of healthy fats Australia?

The Australian Eat For Health guidelines recommend sourcing unsaturated fats from whole foods like avocados, nuts, seeds, and plant-based oils. These foods provide a rich matrix of vitamins, minerals, and dietary fibre alongside healthy monounsaturated and polyunsaturated fats.

Oily fish such as salmon, mackerel, and sardines are excellent sources of essential omega-3 fatty acids, which help reduce systemic inflammation, as supported by PMC5577766. Diabetes Australia recommends oily fish as the preferred source of these protective omega-3 fats.

Australian supermarkets offer accessible plant oils, such as locally produced extra virgin olive oil and canola oil, which are rich in heart-healthy monounsaturated fats. Incorporating a handful of raw almonds or walnuts (about 30 grams) into your daily routine is an easy way to meet your essential fatty acid requirements under local nutrition guidelines.

How much fat per day is recommended?

The Acceptable Macronutrient Distribution Range (AMDR) for total fat intake for Australian adults is established at 20% to 35% of total daily energy intake, as outlined in PMC5577766. For an average adult consuming 8,700 kilojoules (about 2,000 calories) per day, this equates to approximately 45 to 80 grams of fat daily.

The National Heart Foundation of Australia recommends that saturated and trans fats should make up no more than 10% of your daily energy intake. This means the majority of your daily fat intake should come from monounsaturated and polyunsaturated sources.

Replacing saturated fatty acids with polyunsaturated fatty acids is associated with a significant reduction in the risk of cardiovascular disease, according to research in PMC5577766. Rather than adopting a low-fat eating plan, focusing on the quality and type of dietary fat is the most effective way to support long-term heart health and overall wellbeing.