Light or “lite”, 99% fat-free, reduced fat, low fat, less fat, reduced calorie, low calorie, lean, extra lean – are products with these labels always healthier?
First, let’s talk about fat. Fat in foods and drinks is either unsaturated (monounsaturated or polyunsaturated, the latter as omega-3 or -6; or trans-fats), saturated.
These differ based on their chemical structures and properties, including whether they are “saturated” with more hydrogen atoms and are liquid or solid at room temperature. They also differ in their effects on human health.
Past advice on fat
In the early to mid-1900s, discoveries about the energy value of different macronutrients led to the establishment of “Atwater Factors”. These are standardised values of how much energy, or kJ/kcal/calories, a nutrient such as fat or carbohydrate provides to the human body.
Fat was assigned the highest value of 37 kilojoules per gram, indicating it provides the most energy per weight unit (gram) to the human body out of all the macronutrients (more than carbohydrates, protein and alcohol). As it was the most enery-dense, this contributed to a belief that a high-fat diet would lead to weight gain.
Then, around the mid-1900s, various research studies were published about fat and human health, particularly regarding cardiovascular health. A scientist called Ancel Keys and others reported findings of the Seven Countries Study, including a statistical association in population data from seven countries between eating saturated fat and trans fat and an increased risk of coronary heart disease.
Even though the detrimental effects on heart health were not attributed to unsaturated fats in this example study, unfortunately a general feeling of malaise towards all types of fat mostly strengthened. I say mostly because there were some movements from around the 1970s onwards that advocated a high-fat, low-carb way of living – such as the Atkins Diet.
These ongoing “fat is bad” messages led to an explosion in fat-free or reduced-fat food products and marketing that still persists today.
Current thinking on fat
Worldwide, there has been variation in when governments or organisations have issued dietary guidelines for their populations. The Australian Dietary Guidelines were first issued in 1982, in the United States in 1980 and in the United Kingdom in 1994.
Most of the advice has included care with total fat intake, avoidance of saturated and trans fat and a mostly monitored consumption of “healthier” unsaturated fats.