Nutrition science is not without controversy, and the conversation surrounding dietary fat is no different. Let's chew the fat...
Firstly, a brief overview. We refer to fats in three general categories; saturated fat, trans fat and unsaturated fat. Intake of saturated fat (red meat, whole milk dairy and many commercially prepared foods) has long been associated with increased risk of heart disease. Trans fats (predominately found in processed foods) are also known to elicit negative cardiovascular effects. A diet rich in unsaturated fats (nuts, seeds, avocado, olive oil and salmon), however, is linked to improved blood lipid profiles and reduced cardiovascular risk. Fat is also extremely energy, or calorie, dense so it is often targeted for individuals seeking weight loss.
In our quest for a healthier, leaner population a generalised low-fat diet gained traction over past decades. This shift away from excessive fat intake sought to reduce rates of overweight, obesity and cardiovascular disease. While the sentiment was there the general public were not equipped with suitable low fat alternatives, and because fat is a haven for flavour our diets lacked without it. This gave way to diets high in refined carbohydrates, which included the likes of white bread, pasta, processed snack foods and added sugar.
As nutrition science evolved we learnt a lot more about the specific effects of dietary fat, and the health implications associated with excessive intake of refined carbohydrates. We now know refined carbohydrates generate an equal, if not greater, burden of disease when consumed in excess. We determined trans fats to be definitively unhealthy, and as a result significantly reduced these within the food supply. Saturated fats have been somewhat vindicated in recent years with evidence indicating some varieties (stearic acid and lauric acid specifically) have neutral effects on cardiovascular risk, although we still lack convincing evidence that they are helpful. Finally, we know eating unsaturated fats in place of saturated fats or highly refined carbohydrates improves blood lipid profile, and is a staple among some of the world's healthiest regions.
The bottom line? Fats are in. Prioritise olive oils, avocado, nuts and fatty fish, but don't demonise a great piece of steak and whole milk dairy products. Remember though, fats are simply one element of a healthy diet and lifestyle. Focussing on specific nutrients is not the key to a nutritious, health-promoting diet. Emphasise a diet of wholesome foods in sensible combinations instead. When we get the foods right, the nutrients take care of themselves!