Fats are a macronutrient that has attracted controversy and criticism for years.
Is everything you have heard true? Our sports nutritionists explain.
What are fats?
They are essential macronutrients for normal bodily function.
We often use the term for lipids. Common dietary fats include one, two or three fatty acids attached to a glycerol molecule.
What do fats do?
Despite claims that all fat is harmful or inevitably causes weight gain, fat is essential to life.
It is a component of cell membranes and has many other functions:
- Supplying energy: one gram provides 9 kcal.
- Supporting absorption of fat-soluble vitamins A, E, D and K.
- Regulating cholesterol levels.
- Supporting the immune system.
- Contributing to nervous system function and cell signalling.
- Supporting the structure and function of the skin and cell membranes.
What types of fatty acid are there?
Common categories include saturated, unsaturated and trans fats.
Unsaturated fats include polyunsaturated and monounsaturated fats.
A characteristic monounsaturated fatty acid is oleic acid, found in:
- Olive oil
- Almonds, peanuts and cashews.
- Avocado.
Polyunsaturated fats contain two or more double bonds, or unsaturations.
They include omega-3 and omega-6 families, with essential fatty acids we must obtain from food because the body cannot make them.
- Walnuts
- Sunflower seeds.
- Flaxseed and flaxseed oil.
- Salmon, mackerel, herring, albacore tuna and trout.
- Corn oil.
The omega-3 family is of particular interest for several reasons:
- Helping reduce triglycerides.
- Potential effects on heart rhythm.
- Helping limit arterial plaque accumulation.
- Contributing to a small reduction in blood pressure.
- Roles in blood glucose regulation.
- Research into diabetes risk.
- Anti-inflammatory effects relevant to sports injuries and recovery.
Are saturated fats healthy?
Foods containing saturated fat do not all have the same nutritional profile. Effects depend on the type of fat, processing and overall food quality. Nevertheless, dietary guidance recommends limiting saturated fat and favouring unsaturated sources.
Alongside eggs, meat, full-fat dairy and coconut, saturated fats are found in ultra-processed foods such as pastries, desserts, fried products and sauces. The overall dietary pattern matters.
What is cholesterol?
Cholesterol is a steroid lipid in animal cell membranes and tissues. It has essential functions.
Distinguish blood cholesterol from dietary cholesterol supplied by animal-derived foods.
Blood cholesterol is transported in particles you may recognise:
- HDL cholesterol, commonly called “good” cholesterol.
- LDL cholesterol, commonly called “bad” cholesterol. Elevated levels contribute to arterial plaque and can increase the risk of serious health problems.
Where is fat stored?
Eating fat does not automatically mean accumulating body fat.
Fat provides around twice the calories per gram of carbohydrate or protein. Portions of fat-rich foods therefore matter, particularly if your goal is weight loss, while adequate essential fat intake remains important.
Triglycerides are a storage form of fatty acids: three fatty acids plus glycerol form a triglyceride.
When energy intake exceeds expenditure, surplus energy can be stored for future use.
If your body-composition goal is fat loss, a nutritionist can help plan an appropriate calorie deficit. We often say burning fat, but the biochemical term is oxidation.
Foods providing healthy fats
As you know, not all fats are the same.
Healthy fat sources such as avocado, oily fish, nuts and extra virgin olive oil supply nutrients and participate in inflammatory and hormonal processes.
An egg’s unsaturated fats, contained in its yolk rather than added frying oil, occur alongside dietary cholesterol. The body needs cholesterol, but dietary and blood cholesterol are not interchangeable concepts; individual responses and overall diet matter.
A universal limit of 2 eggs per week is not an appropriate rule for everyone. Yolks also provide vitamins A, E and D, folic acid and vitamin B12. Their nutritional context differs from an industrial muffin, processed meat, ultra-processed cheese sauce or crisps.
Consider food quality when deciding which fats to reduce.
Here are some fat-containing foods discussed in this article:
- Oily fish: salmon, herring, tuna and mackerel.
- Nuts and seeds: almonds, peanuts, cashews and chia seeds.
- Fat-rich plant foods: avocado and coconut oil.
- Vegetable oils: olive oil and others.
Fats in an athlete’s diet
Athletes may look like record-breaking machines, but our cell membranes still need lipids.
You may hear that an athlete’s diet should focus on carbohydrate for readily available energy and protein for muscle building.
What about fats?
They also belong in an athlete’s diet. Beyond their everyday functions, they play a role in recovery after training.
Omega-3 polyunsaturated fatty acids can help manage muscle inflammation following exercise, relevant to injury risk and recovery.
Avoid a large fat-rich meal immediately before training when digestion time is limited. Fat can slow digestion and contribute to discomfort.
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