What are ‘good fats’?

‘Good fats’ has become an overused almost meaningless health label.

We advocate a  whole food plant-based diet – a diet built mainly on whole grains, legumes, vegetables, and fruits. This is a low-fat diet because most of the energy these foods provide is in the form of carbohydrates and proteins with only a small contribution from fat. It’s the dietary pattern with evidence for reversal of heart disease and insulin resistance and is of low caloric density, assisting weight loss. The macronutrient ratio (typically >70% carbohydrate, 10-15% protein, 10-15% fat) is a consequence of the composition of our core foods rather than the macro ratio determining our food choices.

“But what about good fats?” is a question or objection often raised when we describe our low-fat dietary approach and the amazing health results we see when people eat this way. People love their fat-rich foods, and the dairy, olive oil and nut industries have successfully dismantled the low-fat diet paradigm during the preceding couple of decades. ‘Good fats’ have gained de facto status as a food group and even many plant-based foodies seem to regard ‘good fats’ as an essential component of every meal. In mainstream nutrition Australians are being encouraged to add hundreds of calories of olive oil to their meals every day in the name of ‘good fats’. Has anyone paused to consider what a ‘good fat’ is? It would seem not when we review the composition of many of these so-called good fats.

Criteria for a ‘good fat’

Whole food: Our first criterion for a ‘good fat’ is that the fat is in the context of a whole food. Vegetable oils and margarine are not ‘good fats’ because they have lost all the fibre and most of the nutrients of their plant of origin (see our No Oil page).

Low in saturated fat: ‘Good fats’ are good because bad fats – i.e. saturated and trans fats – are bad for our health. Any ‘less bad’ fat than these are usually labelled a ‘good fat’ by nutritionists. We can sideline trans fats because they have been largely eliminated from ultra-processed foods, leaving ruminant meats and dairy as the primary dietary source. Saturated fats are widespread in both plant and animal-derived foods. The issue is how much saturated fat does it take to lose the ‘good fats’ tick of approval? The commonly accepted upper healthy limit of saturated fat intake is 10% of total dietary calories. The American Heart Association recommends an even lower target of 5% to 6% of calories from saturated fat. Adding in more calories from foods with a greater percentage of saturated fat than this (e.g. olive oil or avocado) is never going to get us to these targets. How do some common ‘good fats’ compare to these criteria?

Saturated fat as a percentage of total calories:

 

Olive oil, avocado, and many nuts owe their ‘good fats’ label to their high monounsaturated fat content. Monounsaturated fats have a neutral effect on blood cholesterol and metabolic health. We have no requirement for monounsaturated fats other than as a source of calories (energy). Plants with a high monounsaturated content may qualify as ‘good fats’ if they meet our criteria.

Essential fat ratio: The only ‘good fats’ that are essential are two groups of polyunsaturated fats, the omega 6 and omega 3 series. Human requirements for these amounts to only a few percent of daily energy intake and clinical deficiency is extremely rare. What may be more relevant is the ratio (omega-6: omega-3) as the two groups are transformed within the body by the same enzymes, and too much of one may compromise conversion of the other into the long chain form. The modern diet has become skewed towards the omega-6 group, far from the optimal ratio of 4:1 or less. This is thought to contribute to long-term adverse health outcomes. Omega-6 fats are widespread in grains, nuts, seeds, and oils and are more often present in the diet in excess. In contrast, few foods are high in omega-3 fats. The omega-6 to omega-3 ratio of the total dietary pattern is important, rather than that of individual food items. One could eat some high omega-6 meals and counterbalance these with other meals of higher omega-3 content. However, anticipating that something else will compensate for what’s currently on our plate can be a slippery slope in nutrition. Giving the ‘good fats’ tick to foods low in omega 3’s may take people further from an optimal fat ratio. Our final criterion for the ‘good fats’ label is that the item has an omega 6 to omega 3 ratio supporting a total dietary ratio of 4:1 or less. Many foods promoted as ‘good fats’ do not meet this criterion.

Omega 6 to omega 3 ratio in foods of moderate to high fat content:

*Green leafy vegetables are low in fat therefore it takes a lot of them to have a meaningful effect on your omega-3 intake.

The aim of this article was to bring nutrition science into the ‘good fats’ meme to help you make healthier food choices, regardless of where you are on the fats-starches continuum of whole foods, plant-based nutrition. Some individuals and groups may benefit from eating more ‘good fats’ to maintain an adequate calorie (energy) intake. Our personal low-fat, WFPB diet includes ground flaxseed, a few walnuts, a little peanut paste, and tahini as condiments.

Our ‘good fats’ tips:

  1. Source ‘good fats’ from whole foods or minimally processed whole foods.
  2. Limit consumption of ‘good fats’ with a higher saturated fat content, particularly if you have heart disease or type 2 diabetes.
  3. Choose ‘good fats’ with a lower omega 6:3 ratio.
  4. Balance higher intakes of omega 6 predominant ‘good fats’ with increased omega 3 foods.
  5. Be mindful that high-fat foods are calorie-dense and good for weight gain.

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Page created 30th December 2023
Last updated 5th January 2024