Chewing the fat
With supporters of popular diets such as Paleo and LCHF (low carb high fat) putting cream, butter and bacon back on the menu, it’s time to re-examine the evidence. Is saturated fat actually good for us, and how much do we need? HFG senior nutritionist Rose Carr answers a few important questions.
The confusion around saturated fat starts here — our bodies need saturated fats, but we don’t have to eat foods containing them. This is because our bodies are clever and efficient enough to produce most of the different types of fats they need, including saturated fats, from the foods we eat.
So why do our bodies NEED saturated fats? Like all fats, they give us energy, while fat storage provides us with energy reserves, but research also suggests different types of saturated fats are involved in other jobs such as cell communication, regulating hormones and possibly even stopping the development of cancer cells. Some saturated fats also help to strengthen cell membranes.
Why we need fat
- Gives us energy
- Provides energy reserves
- Helps cell communication
- Is important for regulating hormones
- Helps strengthen cell membranes
- Carries fat-soluble vitamins A, D, E and K into our bodies
- Protects internal organs
- Insulates our bodies
- Helps us to feel full
- Enhances texture and taste!
So, we don’t need to eat saturated fats, but they are present in lots of the food we eat and there is clear evidence to show we need to be careful about the amount we consume. The answers below will explain why.
What’s the link between saturated fat and cholesterol?
Diets high in saturated fats have been clearly linked to a higher ratio of total to HDL cholesterol, an indicator of heart disease risk. We tend to talk about saturated fat as one entity but there are many saturated fats with different chemical structures.
More common saturated fats (technically called fatty acids) include palmitic, stearic, myristic, lauric and butyric acids. While research shows that individual saturated fats have different effects on cholesterol, saturated fats in food come in a group, not individually. So to understand what the effect is likely to be on cholesterol levels and assess risk for heart disease, we’re better to focus on research involving people and real food, rather than lab studies.
One such study clearly showed a positive effect on blood cholesterol levels when saturated fats were replaced with unsaturated fats. When dairy fats were replaced with coconut fat, they found a small improvement in the total to HDL cholesterol ratio (which means it’s not quite as bad as butter). However, there was a much greater improvement in cholesterol when saturated fats were replaced with olive oil or rice bran oil and even better again with sunflower, soybean or canola oil. The same trends were evident when beef fat was replaced with the same plant fats.
Is the link between saturated fat and heart disease still compelling?
Yes. Our rates of death from heart disease have dropped dramatically since they peaked in the 1960s and our reduced intake of saturated fats have been an important part of that.
There is a convincing body of evidence that diets high in saturated fat are bad for heart health and we can lower the risk for heart disease by reducing saturated fat intake and replacing it with polyunsaturated fats.
There is increasing research and debate around specific sources of saturated fats and whether some food sources might be better than others. An analysis of 76 studies found cheese and whole-milk dairy products were associated with a reduced risk for heart disease, whereas saturated fat from meat increased this risk, as expected.
And a clinical trial found that cheese did not raise LDL cholesterol as was expected based on its saturated fat content. It should be noted, however, that in this study, the average intake for saturated fat was considerably lower than our average intakes, which may be an important factor.
Research is ongoing but scientists caution against going back to consuming high-fat dairy. The emerging science does not negate the overwhelming body of research that shows that diets high in saturated fats are harmful to our health.
The bottom line? Taking all the evidence into account, the overall advice is still to reduce our intake of saturated fats and replace them with healthier fats from fish, nuts and seeds.
Is the obesity epidemic really due to the introduction of guidelines to eat a low-fat diet?
The first dietary guidelines for Americans, published in 1980, advised steering clear of too much saturated fat and reducing the consumption of total fat was seen as a good way to encourage this. The advice that accompanied these guidelines looked quite sensible and included choosing lean meat and limiting the intake of butter, cream, hydrogenated margarines, shortenings and coconut oil as well as foods made from them. So the real focus was on saturated fats.
At the American Society for Nutrition Annual Meeting in 2014, data presented showed that the start of the obesity epidemic in America coincided with the introduction of the Food Guide Pyramid in 1992. With a new focus on limiting total fat intake it very likely helped to launch the low-fat industry. Low-fat products, often high in refined carbohydrates and kilojoules, replaced fatty foods, and many people ended up consuming the same, if not more, energy (kilojoules) from low-quality, highly-processed carbohydrates. And those on weight-loss diets were usually on low-fat diets. For many people, low-fat diets are not useful long-term, in part because they can be hard to stick to.
It’s probably not entirely fair to blame the obesity epidemic on sticking to these dietary guidelines, given that other messages, such as avoiding too much sugar and maintaining a healthy weight, were clearly overlooked!
What we do know is that since then, people have been eating more kilojoules in total. This outcome was not intended. The lesson has been that concentrating on single nutrients can have unforeseen consequences and it’s better to focus on the quality of the whole diet.
Are saturated fats better and more stable for cooking?
Saturated fats are generally more stable for deep-frying, but we don’t recommend deep frying because food can soak up lots of fat, making it very energy dense. If you’re using oil to quickly stir-fry food, there are plenty of oils that are low in saturated fat, such as canola, rice bran or sunflower oil that will do the trick. When baking, an oil spray is useful — you get a lovely browned effect without using lashings of oil.
I’ve read that I should eat more fat to help me lose weight. Is this right?
Whether you need to eat more or less fat really depends on your starting point and what suits you. Generally, low-fat diets are no longer advised as the best way to lose weight and maintain weight loss. However it’s important to remember that everyone is different and a low-fat diet may suit some people. Look at healthy diets around the world — they can be quite low in fat, as in the traditional diet of Okinawans in Japan, or quite high in fat, as in a traditional Mediterranean way of eating. (See our feature Explore the Mediterranean for more.)
Fat is energy dense, which means a gram of fat provides a little over twice the kilojoules of a gram of protein or carbohydrate. But fat also fills you up and enhances texture, mouthfeel and taste and surely, enjoying our food is part of living a happy, healthy life!
The best diet has lots of variety and is one you can stick to forever. For weight loss, reduce overall energy intake by watching portion sizes and for a healthier diet, replace more saturated fats with unsaturated fats.
How much fat should I be having, then?
Fat is not bad for us. In fact, we need fat to carry the fat-soluble vitamins A, D, E and K into our bodies. And fat (in appropriate amounts) around our internal organs is essential to protect them. Even though there are only two types of essential fats our bodies can’t make, all fats provide a concentrated form of energy, which is great when we need that, and not so good when we don’t!
It may surprise you that on average, New Zealanders consume about the right amount of total fat. The guideline is to get 20-35 per cent of our total energy from fat, and we average around 34 per cent. Fat helps us feel full, so at the lower end of the range we may not feel as satisfied, especially if we eat high-GI carbs instead. At HFG our menu plans usually provide between 30-35 per cent energy from fat.
Where we are not meeting the guidelines is in the proportion of fats in our diet. Many of us still need to reduce saturated fats and substitute those for unsaturated fats. While we now know that not all saturated fats are created equal, there’s still not enough evidence to change the recommendation about reducing specific saturated fats in our diets — rather we have to look at saturated fats as one group. Our menu plans usually provide around six per cent energy from saturated fat, which is well below the upper recommendation of 10 per cent.
If we simply focus on choosing plant-based fats (excluding coconut and palm fats) over animal fats, we’ll get the balance right. We don’t have to give up all saturated fat; it’s about not overdoing it. If cheese is your favourite food, it’s easy to include it in your diet — in appropriate amounts. If you love a little butter on your bread, there’s no reason you can’t fit that into a healthy diet either. But a slab of cheese between bread that has been thickly spread with butter is not likely to fit in your daily diet, unless you have very high energy needs!
The key is to focus on the quality of your overall diet and the amount of saturated fat you consume.
Coconut oil helps the body burn fat
False: If it sounds too good to be true it usually is, and this is no exception! The pseudoscience presented in support of this theory is muddled and, quite simply, wrong. The fact is every 15g tablespoon of coconut fat delivers 550kJ. That’s adding fat, not burning it.
Canola oil and other processed seed oils are not fit for human consumption
False: There’s a lot of nonsense to be found on the internet about canola oil. Don’t believe it! A 2009 British Nutrition Foundation review of culinary oils and their health benefits found canola oil to be high in healthy monounsaturated fats and especially high in ALA (the plant form of omega-3).
Butter is better because it’s more natural
False: At Healthy Food Guide we do prefer a diet based on whole foods closer to their origins, but we still believe it’s a good idea to limit consumption of butter because of the high amount of saturated fat it contains. A small amount of butter within a healthy diet won’t kill you, but if you use a significant amount of spread, whether slathered on bread or in baking, we recommend using a reduced-fat version to reduce the saturated fat. Early margarines contained high amounts of trans fats, but now we can buy spreads with around 60 per cent fat, minimal saturated fats and little, if any, trans fats. We still get trans fats from butter, however our intake of these in New Zealand is very low.
In a nutshell
Fats are classified as saturated or unsaturated, depending on their chemical structure. We don’t have to avoid all saturated fats all of the time, but we can improve heart health by replacing more of them with unsaturated fats such as those in nuts, seeds, avocado, oily fish, lean meat and reduced-fat dairy products.
Saturated fats – what we need less of
- Mostly from animal products: fat in and around meat and in full-fat milk and dairy
- Coconut, palm kernel and palm fats are high in saturated fats
- Typically solid at room temperature
Unsaturated fats – healthy fats
- Most plant oils (other than the above) are unsaturated fats — olive, avocado, canola, rice bran, flaxseed, sesame oils
- Classified as monounsaturated or polyunsaturated, based on chemical structure
- Most polyunsaturated fats are omega-6 fats; some are omega-3 fats. Long-chain omega-3 fats, found in fish oils, are particularly good for heart health and short-chain omega-3 fats are found in some plant foods
- The only fats our bodies can’t make from others are alpha-linolenic acid (ALA, an omega-3 fat) and linoleic acid (LA, an omega-6 fat)
- Typically liquid at room temperature