The Role of Fats

By BodyMatters’ Family Therapist Christie Lomas

Fat has come to be a word that many in our society avoid at all cost, but is fat something to be avoided or is it a vital part of our diet? Before addressing this question, lets clarify a couple of things. I am by no means and expert in nutrition, but as a therapist working with eating issues and given my own interest in healthy eating in addition to often being baffled by the “fats”, I will attempt to bring to light the facts about the fats.

What is the difference between fat and cholesterol?

Fat and cholesterol are both natural components of the body and necessary for good health. For a crude differentiation, fat supplies the energy that keep us alive and kicking, it helps to cushion your bodies organs and protect them from injury. Fat is also important in slowing down the digestive processes so that you are not hungry after eating (more about that later!).

Cholesterol is similar to fat but has different functions. Cholesterol is necessary for nerve function, oestrogen and testosterone production as well as the production of vitamin D from sunlight exposure to the skin. Our bodies generally make all the cholesterol we need and it is found only in dairy and animal products including eggs.

Are all fats the same?

Absolutely not! Here is a brief rundown of the different types of fats.

Saturated Fats: These fats are found in red meat, pork, poultry skin, cheese, milk, ice cream, butter along with some oils such as palm and coconut oil.  Saturated fats have been an important ingredient in diets all over the world for centuries. However, in recent times, they have come to be known by many as the fats to steer clear of due to what was thought to be an association between saturated fats and cardio-vascular disease (CVD). However, what is surprising to many is that different saturated fats can affect us in different ways. For instance, the most recent research has confirmed that consuming diary (including full fat diary) is actually associated with less risk of CVD, not more [1]. Furthermore, the health benefits of coconut oil have recently received attention. Coconut oil has been thought to have the healthy benefits of supporting your heart, brain, skin, immune system and thyroid. It is also thought to stimulate your body’s metabolism [2]. Hence, thinking about saturated fats as one group is misguided as there appears to be health benefits provided by certain types of saturated fats.

Trans fats are a specific type of saturated fat that has gone through a process called hydrogenation. Foods high in trans fats tend to be high in cholesterol. They are found in processed foods, margarine, shortening. Trans fats are worse for cholesterol levels than other saturated fats because they raise the cholesterol that is unhealthy for us (LDL – which carries cholesterol to body tissues and forms deposits on artery walls and blood vessels) and lower the cholesterol that is healthy for us (HDL – which carries cholesterol away from body tissue so the body can get rid of it). Trans fats also trigger inflammation, [3] an overactivity of the immune system that has been implicated in heart disease, stroke, diabetes, and other chronic conditions. They also contribute to insulin resistance [4]

Unsaturated fats

Monounsaturated Fats – Found in high amounts of olive oil, olives and nuts including peanuts, almonds, hazelnuts, pecans; and seeds such as pumpkin and sesame seeds. These can help lower blood cholesterol.

Polyunsaturated Fats –  Found in high concentrations in sunflower, corn, soybean, and flaxseed oils, safflower oils, cottonseed oil, vegetable oils and also in foods such as walnuts, flax seeds, fish and canola oil. Polyunsaturated fats lower total blood cholesterol levels.

Omega 3 & Omega 6 are specific types of polyunsaturated fats. Both are essential for your body to function properly. They are called essential fatty acids because you have to get them through your diet as your body can’t produce these. These essential fats are important for normal development. They have also been thought to be important in the prevention of cancer, heart disease, high blood pressure and arthritis. Omega 3 is found in high amounts of nuts, seeds, canola and soybean oils. An excellent way to get omega-3 fats is by eating fatty fish like tuna and salmon two or three times a week. Good plant sources of omega-3 fats include chia seeds (sold as Salvia), flax seeds, walnuts, and oils such as flaxseed, canola, and soybean. Omega 6 is also found in seeds, nuts and in corn oil.

Now here is an interesting Fact: Eating foods containing monounsaturated and omega 3 fats, stimulate the most Leptin release. Leptin is a hormone, released by the body which decreases your appetite, speeds up your metabolism and gets you moving more.  These fats actually tend to regulate weight in the long run [5]. Polyunsaturated fats also stimulate Leptin release, but less than the Monos and Omegas. Saturated fats, in particular trans fats fall way behind in their production of this hunger stopping hormone.

Hopefully you are getting the picture that fats have an important role in our diet and there are a lot of good things about fats. Here are some more:

Fat helps us to feel full. Have you noticed how low-fat, sugar free foods, leave you feeling unsatisfied, wanting more? There has been a huge increase in the amounts of low fat or fat-free foods available in supermarkets. You can almost buy any food in a lower fat form.  However, if you reduce the fat, the flavour is also reduced. So, the manufacturers of these goods pour in sweeteners to increase the flavour. These sweeteners are usually high in fructose corn syrup. When fructose is consumed, hormones such as Leptin that normally gets released into the body to tell us we are full and to stop eating, don’t get released. So we end up wanting more and eating more.

Fat helps you absorb more nutrients from foods. Did you know that you absorb more of the nutrients from foods like vegetables, if you have consumed some fat? Fat helps the body absorb vitamins such as vitamin A, D,E and K. Hence, too little fat is just as unhealthy as too much.

Fat also brings out other qualities in food, such as flavour. Think about the taste of potatoes boiled in water, and then compare it to the taste of potatoes roasted in oil. So much more pleasure comes from adding fat. And pleasure, when we are talking about food is incredibly important as when you are enjoying your food, “full sensors” are triggered in our brain.

Fat does NOT make you fat! There is actually little evidence supporting the link between fat in the diet and body fat [6-15].  Dr. Walter Willett of the Harvard School of Public Health [16] says it’s a myth that eating specifically high-fat foods makes you fat. What increases weight is eating or drinking more calories than you need from any source be it from fat, carbohydrate, protein or alcohol. What really matters is the type of fat and the total calories consumed in food. Unhealthy fats – the trans fats – increase the risk for certain diseases. Healthy fats – the monounsaturated and polyunsaturated fats, are good for the heart and most other parts of the body, so they do the opposite.

If you hold the hard and fast rule that all fat is bad and deprive yourself, you end up being vulnerable to what is called “deprivation-driven eating”  and again, those hunger-stopping hormones like Leptin won’t get released and do their job properly, which means you eat and want more and more.

Linda Bacon in her book “Health at Every Size”[5], suggests that allowing yourself to enjoy some high fat foods may be what will actually help you to enjoy these foods in moderation in a healthy way.

Did you know that we are biologically driven to crave fat? Our bodies connect fat in our food with safety and security. When we don’t eat enough fat, our bodies become preoccupied with how we can get it.  This is a survival reaction to protect us during times when food is scarce. This is also why typical diets fail. At some point during a diet, your biological drive for fat kicks in and you fall off the wagon so to speak and subsequently feel guilty and blame yourself for the failure. However, the truth is…you didn’t fail, the diet failed you! We now know the reality of  low-fat diets…in the long run, they just don’t work. Even researchers from the Harvard School of Public Health are now saying that the low-fat campaign is not supported by scientific evidence [17].

So, what to do?

Most people don’t get enough of these healthy unsaturated fats each day and unfortunately, there are no strict guidelines that have been published regarding their intake. One good tip is to choose foods rich in unsaturated fats over foods rich in saturated fats whenever possible. The Harvard School of Public Health Nutrition Source has recently produced a great chart, adapted from the work of Mozzaffaria [3,12 -14] which helps clarify where we should be heading with the consumption of fats.

References

[1] Feinman, R.D. (2010). Saturated Fat and Health: Recent Advances in Research. Lipids. 45(10), 891-892.

[2] Mercola, J. (2010). The Truth About Saturated Fats and The Coconut Oil Benefits. Mercola Articles. Retrieved Feb 23, 2013. From http://articles.mercola.com/sites/articles/archive/2010/10/22/coconut-oil-and-saturated-fats-can-make-you-healthy.aspx

[3] Mozaffarian D, Pischon T, Hankinson S, et al. (2004). Dietary intake of trans fatty acids and systemic inflammation in women. Am J Clin Nutr, 79, 606-12.

[4] Riserus U, Willett WC, Hu FB. (2009). Dietary fats and prevention of type 2 diabetes. Prog Lipid Res., 48, 44-51.

[5] Bacon L (2010). Health at every size: The surprising truth about your weight. Benbella: USA.

[6] Appel L, Sacks F, Carey V, et al. (2005). Effects of protein, monounsaturated fat, and carbohydrate intake on blood pressure and serum lipids: results of the OmniHeart randomized trial. JAMA. 294, 2455-64

[7] Beresford S, Johnson K, Ritenbaugh C, et al. (2006). Low-fat dietary pattern and risk of colorectal cancer: the Women’s Health Initiative Randomized Controlled Dietary Modification Trial. JAMA. 295, 643-54.

[8] Howard B, Manson J, Stefanick M, et al. (2006). Low-fat dietary pattern and weight change over 7 years: the Women’s Health Initiative Dietary Modification Trial. JAMA. 295,39-49.

[9] Howard B, Van Horn L, Hsia J, et al. (2006). Low-fat dietary pattern and risk of cardiovascular disease: the Women’s Health Initiative Randomized Controlled Dietary Modification Trial. JAMA. 295, 655-66.

[10] Mente A, de Koning L, Shannon HS, Anand SS. (2009). A systematic review of the evidence supporting a causal link between dietary factors and coronary heart disease. Arch Intern Med. 169, 659-69.

[11] Sacks FM, Bray GA, Carey VJ, et al. (2009). Comparison of weight-loss diets with different compositions of fat, protein, and carbohydrates. N Engl J Med. 360, 859-73.

[12] Mozaffarian D, Micha R, Wallace S. (2010). Effects on coronary heart disease of increasing polyunsaturated fat in place of saturated fat: a systematic review and meta-analysis of randomized controlled trials. PLoS Med. 7, e1000252.

[13] Mozaffarian D, Hao T, Rimm EB, Willett WC, Hu FB. (2011). Changes in diet and lifestyle and long-term weight gain in women and men. N Engl J Med. 364, 2392-404.

[14] Mozaffarian D, Katan M, Ascherio A, Stampfer M, Willett W. (2006). Trans fatty acids and cardiovascular disease. N Engl J Med. 354, 1601-13.

[15]  Hooper L, Summerbell CD, Thompson R, et al. (2011). Reduced or modified dietary fat for preventing cardiovascular disease. Cochrane Database Syst Rev. CD002137.

[16] Harvard School of Public Health (2012). Ask the Expert: Healthy Fats. The Nutrition Source. Retrieved Feb 13, 2013. From http://www.hsph.harvard.edu/nutritionsource/healthy-fats/

[17] Hu, Frank B., JoAnn, E. Mason, and Walter C. Willet. (2001).“Types of Dietary Fat and Risk of Coronary Heart Disease: A Critical Review”, Journal of the American College of nutrition 20, no.1,  5-19.