What’s the story?
There is a lot of confusion and conflicting information out there about how much and what type of fats we should be eating. As fitness professionals we should be recommending the FSA guidelines of not more than 11% saturated fatty acids and not more than 35% total fat intake. https://www.ptdirect.com/training-design/nutrition/national-nutrition-guidelines-united-kingdom
However, there is a lot of evidence to show that saturated fat is not associated with heart disease risk.
All fats have a similar structure of a chain of carbon atoms bonded to hydrogen atoms. Depending on their chemical structure, fats are classified as saturated or unsaturated (monosaturated or polyunsaturated). Saturated fats consist of a straight chain of carbon atoms. This flat structure allows them to ‘pack’ easily and they form a solid at room temperature such as butter, lard and coconut oil. Monosaturated fats have a kink in the chain making them less likely to pack and allowing them to stay liquid at room temperature such as olive oil and sunflower oil. Polyunsaturated fats have more kinks allowing them to stay liquid at cold temperatures such as fish oil. Trans fats are liquid vegetable oils which have been hydrogenated by the food industry and turned into solid fats. They are used in hardened margarine, packaged backed goods, snack foods and fried fast food.
It is very difficult for scientists to understand the relationship between diet and health as trials would need to control the diet of thousands of people of many years to give accurate results. Most studies rely on food recall and self-reporting which can be very subjective. Randomised controlled trials are needed to allow scientists to make clear conclusions.
The study that gave us the theory that saturated fat is bad for us was published by an American biochemist, Ancel Keys, in 1953 and he showed an apparent relationship between the amount of fat in the diet and heart disease in seven countries. You can read it here.
From this research we were advised to cut fat intake to 30% of total energy and saturated fat to 10%. However as other studies have shown correlation is not causation; causation can only be proved by randomised controlled trials.
Research since the 1970s show that things are not as straightforward as previously thought and that eating saturated fat is not all bad but not all good either.
Several recent review studies that combined data from multiple other studies, found that there really is no link between saturated fat consumption and heart disease.
A review of 21 studies with a total of 347,747 participants, published in 2010 concluded: there is absolutely no association between saturated fat and heart disease. https://www.ncbi.nlm.nih.gov/pubmed/20071648
Another review published in 2014 looked at data from 76 studies (both observational studies and controlled trials) with a total of 643,226 participants. They found no link between saturated fat and heart disease
You will be familiar with HDL (good cholesterol) and LDL (bad cholesterol) but it now seems more complex than this. Research shows that saturated fat is linked with raised levels of LDL which in turn is linked with raised cardiovascular risk. However, there are two types of LDL – type A (large buoyant) and type B (small dense). Type A is associated with saturated fat intake, but type B is associated with carbohydrate intake and is linked to cardiovascular disease. Read more here.
Despite the evidence that saturated fat is not associated with heart disease risk, it also doesn’t prove that eating more saturated fat is good for you.
Until the picture becomes clearer, dieticians are recommending we stick to the current guidelines. We need more data and research before we change the recommendations, to try and avoid confusing the public further.
The problem is that the food industry has filled the gap left by saturated fat with high levels of sugar and there is mounting scientific evidence to show that diets high in sugar are a risk factor for metabolic syndrome.
How do we help our clients?
The advice we can give our clients and class members is:
Use the existing guidance on food groups and recommended intake from the Eatwell guide and also:
- Learn to read labels and look at the ingredients list.
- Don’t assume low fat and fat free is healthier.
- Don’t forget that all types of fat are calorie dense and if the calories you eat exceed the calories you burn you will gain body fat.
- Trans fats are bad for you, all research shows this, so avoid them at all costs.
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Blog post author: Helen Tosdevin