Is fat-free better than full fat?

When looking at food diaries, I often see low-fat products. But are those better for health and weight management than the original version? Despite the assumption that fat-free or low-fat products are a healthier choice, the simple answer is no. They are not and won’t make much difference if trying to manage weight. Let me explain why.

Fat is a macronutrient

The other macronutrients are proteins and carbohydrates, which are all essential for our health. We need fat to function as it is an integral part of our cell membranes; it is used for energy production and to absorb fat-soluble vitamins, as well as insulating and protecting our organs; many hormones and 60% of the brain are made of fat.

Fat doesn’t make you fat

Any excessive kcal intake is converted into triglycerides – and often, we exceed kcal intake from carbohydrates/sugars sources. The right amount of fat will be used by the body for the functions mentioned above so it is vital to include fat sources in our meals.

Having a fat-free yoghurt instead of a full-fat one, won’t make much difference for weight management: it has less total kcal, but has more sugars (almost double on average), which are the simplest and most immediate form of energy for our body. If those sugars are not immediately used for energy, they will be stored as fat.

Fat-free products can also give the wrong idea that because that food doesn’t contain fat, it can be eaten deliberately. This is not the case because, as mentioned above, all excessive kcal from all macronutrients will be converted into fat. This highlights that weight management is not only down to fat intake but to food composition and balance between macronutrients. 

Fat adds flavour

Fats in meals not only add flavour but also increase the sense of satiety of that meal. Linking to the example of the fat-free yoghurt above, this will be perceived as less satiating than the full-fat one because of the lack of fats. Fat also helps to balance the glycaemic index (GI) of a meal and slows gastric emptying. GI means how quickly food spikes our blood sugar levels. Also, this will increase satiety and avoid the dreaded sugar rollercoaster of highs and lows that leave us reaching for sugary treats/snacks a few hours after a main meal.

Fat content is substituted in low-fat products

In low-fat or fat-free products, the fat content is usually substituted with carbohydrates or other fat-based substitutes to keep the taste and texture. Examples of carbohydrates used are sugars, fruit purees (high in sugars), gums and other kinds of fibres, which in excessive quantities, can cause gut distress.

Fat-based substitutes are just very processed fats, which become such large molecules that can’t be digested and so won’t add to the kcal count. Those large molecules can also cause digestive distress and prevent the absorption of fat-soluble micronutrients from a meal. A continuous intake of these kinds of nutrients can impact our gut health and potentially lead to irritable bowel syndrome (IBS) style symptoms or poor absorption of nutrients.

Not all fats are equal

There are big 'families' of fats: unsaturated, polyunsaturated, monounsaturated and trans/hydrogenated fats. While trans/hydrogenated fats are very processed and can increase inflammation and fat accumulation, all other fats are necessary. Different foods have different percentages of all those kinds of fats, which are used by the body for various functions.

Monounsaturated fats such as those in olive oil, and polyunsaturated fats such as omega-3 in oily fish, can help lower inflammation, while saturated fats like cholesterol are needed for hormone production. The WHO (World Health Organisation) recommends that 15%-30% of energy intake should come from fats, preferably mono and polyunsaturated, from sources such as fish, nuts, seeds and vegetable oils.

As a nutritionist, I believe it is OK to enjoy full-fat produce and is actually advisable. If trying to manage weight, obesity or cardiovascular health problems, it is better to reduce the total quantity of ingested fat than to indulge in fat-free produce, thinking these are a healthier option.