Myths Around Fats – The Evidence

1. All fats are the same

The general public are often confused about nutrition findings and recommendations when it comes to fat; that there is only one type of fat and it is all bad for you. However in reality there are several different types. The two main types being saturated fat and unsaturated fat.

Saturated fats are commonly found in animal products such as butter, cheese, processed meats, junk food and pastries. In saturated fats, all the carbon atoms in the fatty acid tail are fully saturated with hydrogen atoms so there are no double bonds. Saturated fats tend to have higher melting points than their corresponding unsaturated fats, and are therefore solids at room temperatures. There is an abundance of research which has linked high dietary intakes of saturated fats with raised cholesterol levels and therefore an increased risk of cardiovascular diseases including strokes and heart attacks (British Nutrition Foundation, 2019).

The current recommendations are not to exceed more than 10% of total calorie intake from saturated fats, and to replace saturated fats with unsaturated fats when possible (British Nutrition Foundation, 2019). For men, no more than 30 grams per day and for women, no more than 20 grams per day of saturated fat (NHS Live Well website, 2020).

Unsaturated fats are found primarily in oils from plants and oily fish, and unsaturated fats can be broken down further into polyunsaturated or monounsaturated. In this type of fat, one or more of the carbon bonds are not fully saturated with hydrogen atoms and therefore create a double bond. If there is one double bond, then the fat is monounsaturated and if there is more than one it is polyunsaturated.

Increasing amounts of unsaturated fats in the diet can help to maintain or reduce blood cholesterol levels, which can decrease your risk of heart disease and may also help decrease the risk of type 2 diabetes.

Therefore, not all fats are the same and shouldn’t be treated as such. To reduce the risk of cardiovascular disease in the future it is recommended to reduce the amount of saturated fat in the diet and swap it for higher levels of unsaturated fats (British Nutrition Foundation, 2019).

 

2. Eating carbs will make me fat

There is a lot of confusion surrounding carbohydrates, possibly from trends like the Atkins diet back in the 1990s. Many people now think that carbohydrates are linked with weight gain and are therefore ‘bad for you’. However, carbohydrates are the body’s main source of energy in a healthy balanced diet, providing about 4 kilocalories (kcal) per gram (NHS, 2017).

There are three different forms of carbohydrates; sugar, starch and fibre.

No specific nutrient cannot make you fat on their own. For weight gain to happen, you need to regularly eat more calories than you burn each day. In fact, gram for gram, carbohydrate contains fewer than half the calories of fat (fat contains 9 kcal per gram!).

Wholegrain varieties of starchy foods (or complex carbohydrates) are great sources of fibre, and these include things such as brown rice, brown bread, quinoa and sweet potatoes. Foods high in fibre add bulk to your meal, making you feel fuller for longer, aid with digestion and prevent constipation.

However foods higher in sugar and lower in fibre (also known as simple carbohydrates) for example white pasta, soft drinks, biscuits and chips, are often high in calories, and eating these foods too often can contribute to you becoming overweight (NHS, 2018)

 

3. How much fat is too much fat?

Dietary fat can have a significant impact on our overall health and metabolism. Inadequate fat intake actually impairs absorption of fat-soluble vitamins and leads to a reduced production of hormones and lipoprotein particles, whereas excess fat can contribute to inflammation, obesity and steatosis in distal organs, for example, the liver. (Botchlett & Wu, 2018) There is no specific recommended daily intake for total fat, but the current acceptable macronutrient distribution range is 20–35% of total daily calories (NHS eatwell guide, 2020).

 

4. Fat will raise my cholesterol

Monounsaturated and polyunsaturated fats don’t raise total cholesterol or LDL cholesterol (otherwise known as the ‘bad’ cholesterol). Unsaturated fats can actually help to reduce LDL cholesterol and increase HDL (known as the ‘good’ cholesterol). Trans fats however do raise cholesterol and should therefore be minimized (NHS, 2020).

There is also research that links saturated fat intake with healthy levels of total cholesterol. Saturated fats may increase LDL and HDL cholesterol, or they may have a neutral effect. However, it is still recommended to limit your daily intake of saturated fat due to the risks of cardiovascular diseases (Malhotra, 2013)

 

5. Eating fats will make me fat

One gram of fat, whether saturated or unsaturated, provides approximately 9 kilocalories (kcal) of energy, compared with 4 kcal for both carbohydrate and protein (NHS, 2017). It is easy to assume that fat is the root cause of weight gain.  However, similar to the myth around carbohydrates and weight gain, no specific nutrient cannot make you fat on their own. For weight gain to happen you need to be regularly eating more calories than your body burns each day (British Nutrition Foundation, 2019). Therefore, those individuals with diets that are high in saturated foods will have a higher calorie intake then those who have lower saturated fat intakes. This can also occur in diets which have an excess number of calories from carbohydrates as well.

 

6. I need to eat a low-fat diet to look after my heart

The 4 most common types of fat are: saturated, polyunsaturated, monounsaturated fat, and trans-fats. Saturated fat is solid at room temperature and the type of fat often found in things like red meat, full fat dairy & coconut oil. Foods that contain monounsaturated fats are things such as salmon, avocados, olive oil, and nuts. Polyunsaturated fats are found in most vegetable oils including sunflower, corn, flaxseed, and soybean oils. Trans-fats are made during the processing and manufacturing of foods, helping increase the shelf-life of foods (common in fast foods and ready meals).

Fat is an essential nutrient that the body needs in order to function properly. Fats provide vital energy, help you to absorb certain vitamins & minerals, help you to maintain body temperature, and insulate the body’s vital organs and bones. Having a balanced diet is a must for everyone. By following a ‘Mediterranean’ style diet (plenty of fruit and veg, lentils, grains & oily fish), individuals have seen rates of CVD and related risk factors reduce (Shi, et al., 2016). This diet also tends to be low in red and processed meats.

You do not need to eat specifically a low-fat diet to improve heart health. However unsaturated fats (oily fish, avocados, nuts and seeds) have been proven to reduce LDL cholesterol, a major risk factor for heart disease (Firuhi, et al., 2018).

 

7. Cutting out all fat is good for my heart

This is quite a drastic approach and isn’t necessary. Excluding all fat can mean losing out on essential nutrients and fatty acids that our bodies need, such as omega-3 and omega-6 fatty acids. These polyunsaturated fats are found in oily fish, nuts, seeds and the oils made from them (such an olive oils). Omega fatty acids can increase the levels of HDL cholesterol and reduce risk factors such as high blood pressure (Endo & Arita, 2016) (Minihane, et al., 2016).

 

8. Butter is better

Butter is high in saturated fats and calories & should be restricted to smaller amounts, or you should think about using alternatives for everyday eating. Mono or polyunsaturated fats (olive oil or sunflower spreads) or liquid oils can be used when cooking or baking instead of butter. Butter is however a good source of vitamin A, which is needed for good skin health and immune function. Eating butter as part of a healthy balanced diet should be recommended, rather than cutting it out or consuming in excess (Pimpin, et al., 2016)

 

9. Any kind of meat is bad for my heart

The leaner meats such as chicken and turkey (without the skin) are healthier options than red or processed meats as they are lower in saturated fat. Red meats can be very high in saturated fats, but may also have added salt which can raise blood pressure. A lot of research has been done into red/ processed meats and heart disease; however, the results have been inconsistent. Red meat also tends to have higher levels of sodium, increasing blood pressure for most individuals and putting those who already have hypertension more at risk of cardiovascular diseases (Wolk, 2016), (Wyness, 2016), (O’Connor & Campbell, 2017).  Unprocessed, leaner cuts of red meat can be consumed as part of a healthy balanced diet (Malhotra, 2013).

References

Botchlett, R. & Wu, C., 2018. Diet Composition for the Management of Obesity and Obesityrelated Disorders. J Diabetes Mellit Metab Syndr., Volume 3, pp. 10-25.

British Nutrition Foundation, 2019. SACN report on saturated fats and health published today. [Online] 
Available at: https://www.nutrition.org.uk/nutritioninthenews/new-reports/sacn-sat-fat.html?cf_chl_jschl_tk=33310fa3bc5d6c77575e2153671c523378753799-1578923773-0-AQLqa3f92BFapD1513XzDb8U_29DxhllF-tDvNkgJOHB1havEge8eeBAg2Huengbmm63MWKE_CF0Tf0o2ObygSW11CxmgLNmZM5opSh
[Accessed 13 January 2020].

Endo, J. & Arita, M., 2016. Cardioprotective Mechanism of Omega-3 polyunsaturated fatty acids. Journal of Cardiology, Issue 67, pp. 22-27.

Firuhi, N. G., Krauss, R. m., Taubes, G. & Willett, W., 2018. Dietary fat and cardiometabolic health: evidence, controversies, and consensus for guidance. the BMJ, 10(11), pp. 1-8.

Malhotra, A., 2013. Saturated fat is not the major issue. BMJ, Volume 347, p. f6340.

Minihane, A. M. et al., 2016. Consumption of Fish Oil Providing Amounts of Eicosapentaenoic Acid and Docosahexaenoic Acid That Can Be Obtained from the Diet Reduces Blood Pressure in Adults with Systolic Hypertension: A Retrospective Analysis1–3. The Journal of Nutrition, Nutrition and Disease, pp. 516-523.

NHS, 2017. Fat: the facts. [Online] 
Available at: https://www.nhs.uk/live-well/eat-well/different-fats-nutrition/
[Accessed 13 January 2020].

NHS, 2018. The truth about carbs. [Online] 
Available at: https://www.nhs.uk/live-well/healthy-weight/why-we-need-to-eat-carbs/
[Accessed 13 January 2020].

O'Connor, L. E. & Campbell, W. W., 2017. Red Meat and Health; Getting to the Heart of the Matter. Nutrition Today, 52(4), pp. 167-173.

Pimpin , L. et al., 2016. IsButterBack?ASystematicReviewand Meta-AnalysisofButterConsumptionand RiskofCardiovascularDisease,Diabetes,and TotalMortality. PLOS One, 11(6), pp. 1-18.

Shi, A., Tao, Z., Wei, P. & Zhao, J., 2016. Epidemiological aspects of heart diseases (Review). EXPERIMENTAL AND THERAPEUTIC MEDICINE , Issue 12, pp. 1645-1650.

Wolk, A., 2016. Potential health hazards of eating red meat. Jourmal of Internal Medicine, Issue 281, pp. 106-122.

Wyness, L., 2016. The role of red meat in the diet: nutrition and health benefits. Proceedings of the Nutrition Society, Issue 75, pp. 227-232.