The Truth About Fat

by Bonnie Bayley

Not all fats are created equal. Here’s the lowdown on which fats you should include in your diet – and the ones to avoid.
Our thinking about dietary fats has had a major shake-up in recent years. Not that long ago, foods with ‘low-fat’ or ‘fat-free’ on the label earned an instant health halo, and we viewed avocados, nuts and dairy foods as a fast-track to weight gain.
These days, we’re increasingly aware that fat (the right kind, that is) is an important part of a healthy diet, helping the body absorb nutrients, produce hormones and build healthy cell membranes.
And if you were worried about fat making you fat, consider this: a 2015 study found low-fat diets ironically don’t lead to greater weight loss in the long term than other diets, including higher-fat ones.[1,2] As with everything, it comes down to moderation.
Here is your guide to the good, the bad and the ‘in-between’ fats.

Good fats
Unsaturated fats are the ‘good guys’ of the fats world, helping to reduce the risk of heart disease and lower cholesterol levels. Plus, they have beneficial effects on insulin sensitivity and may help reduce risk of type 2 diabetes, according to a Harvard study.[3] There are two main types:

  • monounsaturated fat?: ‘Mono’ refers to one unsaturated chemical bond (compared to ‘poly’, which means multiple bonds.) You’ll find this type of fat in avocados, olive, canola and peanut oil and some nuts, such as cashews and almonds.
  • polyunsaturated fat: ?There are two main types of polyunsaturated fat: omega-3 and omega-6 fatty acids. Omega-6s are found in margarine spreads, sunflower and sesame oils, sunflower seeds and nuts (such as walnuts, pecans, brazil and pine nuts). Good sources of omega-3s include oily fish, walnuts, linseed (flaxseed) and chia seeds. For most of us, getting enough omega-6 fats isn’t an issue, but we need to boost our omega-3 intake.

Bad fats
Trans fats are a double metabolic whammy, spiking harmful LDL cholesterol and lowering the beneficial HDL kind, increasing the risk of heart disease and stroke. Thankfully, we have relatively low levels in our food supply, but trans fats still lurk in foods that use partially hydrogenated vegetable fats like margarine, deep-fried foods, biscuits, cakes and pastries.
In recent years, saturated fat (found in full-fat dairy, fatty meats, coconut oil, deep-fried food, cakes and biscuits) has sparked debate, with a controversial 2010 study challenging its link to cardiovascular disease.[4] However, leading health organisations around the world advise limiting it, based on the weight of scientific evidence.

There’s no doubt processed foods are harmful, but full-fat dairy in particular (butter excepted) may be ok to enjoy occasionally.
The bottom line: focus mostly on healthy, unsaturated fats, within a whole foods-based diet.


[1] Tobias DK, Chen M, Manson JE, et al. Effect of low-fat diet interventions versus other diet interventions on long-term weight change in adults: a systematic review and meta-analysis. Lancet Diabetes Endocrinol 2015;3(12):968-979.
[3] Risérus U, Willett WC, Hu FB. Dietary fats and prevention of type 2 diabetes. Prog Lipid Res. 2009;48(1):44-51.
[4] Siri-Tarino PW, Sun Q, Hu FB, et al. Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease. Am J Clin Nutr. 2010;91(3):535-546.

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