In the last blog post, we discussed why dietary fats often receive less attention than proteins or carbs from a marketing and fuelling perspective. We also realised that dietary fats have an important role for our health and well-being. This naturally raises some follow-up questions, so today we are discussing what different types of dietary fats exist — and which should we consume more of?
Saturated vs unsaturated: a matter of chemical bonds
Starting with the first question: what are the different types of dietary fat? Initially, we can distinguish between saturated and unsaturated fats. Chemically, this difference refers to the bonds between the carbon atoms in their structure. Saturated fats have single bonds, while unsaturated fats have one or more double bonds (Astrup et al., 2021). This small structural discrepancy actually leads to important differences in the behaviour of the compound.
But these are not the only subtypes. Unsaturated fats can be divided into monounsaturated and polyunsaturated — a distinction based on how many double bonds the compound has. One more way unsaturated fats can be divided is into trans- or cis-fats (Jeukendrup & Gleeson, 2023), based on the chemical shape of the compound. In short: the number of double bonds determines whether a fat is mono- or polyunsaturated, while the configuration around those bonds determines whether it is cis or trans (Oteng & Kersten, 2020).
These distinctions shape the nature of the food product: think of the difference between olive oil (unsaturated) and butter (saturated). And these food choices provide some insight into what the guidelines suggest we should consume.
Saturated fats: caution, but with nuance
Looking at dietary fat consumption, current dietary guidelines recommend limiting saturated fat intake (Astrup et al., 2021; Jeukendrup & Gleeson, 2023). That would suggest that foods such as butter and fatty meats should be limited. However, there is more to the conversation than the initial data related to mortality or comorbidities suggests.
It does seem that saturated fats from dairy (full-fat milk, cheese, yoghurt) may not lead to the same comorbidities as other saturated fats (Jeukendrup & Gleeson, 2023). These health associations may be the result of the food matrix and the eating habits of individuals. If the majority of saturated fats in the diet come from dairy, that person may have a higher overall diet quality compared to someone who gets most of their saturated fats from ultra-processed foods and fatty meats.
From this we can understand that observational associations in epidemiological research do not necessarily tell us that saturated fats cause the outcome. With the data available at the moment, it is wise to approach saturated fats with caution and consume foods with that profile in moderation. Additionally, trans fats — technically a type of unsaturated fat — should also be approached with caution.
Unsaturated fats: the ones to lean on
On the other hand, unsaturated fats in the cis form are a worthwhile addition to anyone’s eating habits. Foods such as nuts, seeds, and avocado can provide essential fatty acids, contributing to our well-being and reducing mortality risk (Kim et al., 2021). Additionally, foods rich in unsaturated fats contain other nutrients essential for our well-being, such as fibre, minerals, and vitamins. Therefore, people should include unsaturated dietary fats from foods naturally rich in the nutrient.
Still, one must keep an eye on total fat intake due to its energy density. Overconsumption of fatty foods may lead to a positive energy balance, which in turn could lead to weight gain and negative health outcomes from higher body fat accumulation.
The bottom line
Fat as a macronutrient has essential roles within the human body as a catalyst for health and well-being. However, not all dietary fats are equal. People should be cautious about saturated fats and integrate unsaturated fats more prominently into their eating habits. The ultimate goal is not to create panic around a specific type of nutrient, but to understand the different sources of fats and build balanced, varied eating habits that fit your lifestyle.
📚 Part of our macronutrient series. Related: The forgotten macronutrient · Carbohydrate types · Animal vs plant-based protein
References
Astrup, A., Teicholz, N., Magkos, F., Bier, D. M., Brenna, J. T., King, J. C., Mente, A., Ordovas, J. M., Volek, J. S., Yusuf, S., & Krauss, R. M. (2021). Dietary saturated fats and health: are the U.S. guidelines evidence-based? Nutrients, 13(10), 3305. https://doi.org/10.3390/nu13103305
Jeukendrup, A., & Gleeson, M. (2023). Sport nutrition (4th ed.). Human Kinetics.
Kim, Y., Je, Y., & Giovannucci, E. L. (2021). Association between dietary fat intake and mortality from all-causes, cardiovascular disease, and cancer: a systematic review and meta-analysis of prospective cohort studies. Clinical Nutrition, 40(3), 1060–1070. https://doi.org/10.1016/j.clnu.2020.07.007
Oteng, A.-B., & Kersten, S. (2020). Mechanisms of action of trans fatty acids. Advances in Nutrition, 11(3), 697–708. https://doi.org/10.1093/advances/nmz125