For a long time fat has been labeled as the bad guy when it comes to weight loss and good health. The principle of the low-fat diet started out simple: “Eat less fat!” This diet then evolved to: “Eat good fats, not bad fats!” Today we are advised to: “Eat good fats in moderation, limit bad fats, and steer clear of really bad fats!” Confused yet
Somewhere along the way this hierarchy of fats was created, labeling fats as good, bad, and evil. To better understand this classification, it is important to understand the different types of fats, their function in the human body, and what makes some better than others when it comes to health and weight loss.
Fat Classification:
Aside from being classified as good, bad, and evil, fats are also classified as natural and unnatural. Natural fats are in foods derived from plants and animals. These fats are further classified as saturated, monounsaturated, and polyunsaturated. Together, they play a vital role in the human body including temperature regulation, hormone production, maintenance of healthy cells, and vitamin absorption.
Unnatural fats occur when the above natural fats are chemically altered through human manipulation. This is done in order to increase the shelf-life of many processed foods. These fats are known as “trans fats,” and have absolutely no role in the human body.
From the above explanation, one may conclude that natural fats are good, and unnatural fats are bad. Unfortunately, this is only half true. There is no doubt that unnatural fats are bad, however, the classification of natural fats as good is not so clean cut.
Natural Fats:
To understand if a fat is saturated, monounsaturated, or polyunsaturated, we must delve into some basic biochemistry. Fat is composed of many hydrogens attached to a chain of carbons. If the carbon chain is holding the maximum number of hydrogens possible, then it is considered full, or saturated. If the carbon chain is not full, then it is considered unsaturated. Depending on how many hydrogens are missing determines if the fat is monounsaturated (less are missing) or polyunsaturated (more are missing).
Natural Fat #1: Saturated Fat
Saturated fats are found mostly in animal products such as meat, cream, cheese, and butter. Although they are natural fats, they have been linked to adverse health effects. Some of these include, increased bad cholesterol, decreased good cholesterol, and increased risk for cardiovascular diseases, heart attacks, and strokes.
The American Heart Association recommends that less than 7% of total calories come from saturated fat. For a 2000-calorie diet, this would mean about 15 grams per day. The average American consumes more than 2 times this amount! This helps to explain why heart disease is the number one killer of Americans.
Natural Fat #2: Monounsaturated Fat
Monounsaturated fats come from plant products such as canola oil, olive oil, nuts, and avocados. Consuming these foods in place of foods high in saturated fats has been linked to a decrease in cardiovascular disease and high blood pressure. Using monounsaturated fats to replace carbs in the diet has been shown to improve blood glucose control and lower blood triglycerides in type 1 diabetics.
In order to experience these beneficial health effects, it is important to understand that monounsaturated fats should REPLACE saturated fats and carbohydrates. This means that just adding monounsaturated fats will not result in improved health if no other dietary changes are made.
Natural Fat #3: Polyunsaturated Fat
Polyunsaturated fats come from both plant and animal products. Omega-3’s and Omega-6’s are two well known polyunsaturated fats and are unique in that they are the only 2 essential fats. This means, that unlike other fats, the body cannot make them and they must be consumed in the diet. This warrants a closer look at each of these polyunsaturated fat
Omega-3
Omega-3’s have many beneficial health effects, including normal brain function, decreased risk for cardiovascular disease, and decreased inflammation. Normal brain function includes everything from infant brain development to treating ADHD, depression, and other mental illnesses. Omega-3’s can decrease the risk for cardiovascular disease by lowering bad cholesterol, raising good cholesterol, and preventing the formation of blood clots. Their anti-inflammatory properties are effective in alleviating conditions such as arthritis and irritable bowel syndrome.
There are 3 basic forms of omega-3’s: alpha linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). It is EPA and DHA that provide the beneficial health effects. The body is able to make EPA and DHA from ALA, however, ALA must be consumed in the diet in order for this to occur. EPA and DHA can also be directly consumed in foods such as salmon, mackerel, halibut, and tuna. ALA can be found in plant sources such as flaxseeds, canola oil, pumpkin seeds, and walnuts.
Omega-6
The other essential polyunsaturated fat is omega-6. Omega-6 is necessary for normal skin and hair growth. Unlike omega-3, omega-6’s are pro-inflammatory, meaning that they promote the inflammation of joints and organs. There are some beneficial health effects of omega-6, however, this is only in conjunction with omega-3. Truth be told, omega-6 can actually inhibit the body from experiencing the beneficial health effects of consuming omega-3.
As previously stated, omega-3’s are only effective as EPA and DHA either from direct consumption, or when converted from ALA. The presence of omega-6 inhibits the conversion of ALA to EPA and DHA, leaving the body with an abundance of unusable ALA.
This does not mean that foods with omega-6’s should be avoided (remember they are an essential fat). This only means that the right amount of omega-6 needs to be consumed with the right amount of omega-3. The recommended ratio of consumption is 4:1 (omega-6:omega-3). The average American diet has a ratio of 40:1 (omega-6:omega3)! This is because omega-6’s are present in common oils added to processed foods (soybean and corn oils). Cutting back on these foods and replacing them with foods high in omega-3 can help optimize the positive powers of these fats.
Unnatural Fat #1: Trans Fat
Trans fats are the unnatural fats that occur during food processing. Oils added to processed foods are hydrogenated in order to prolong the product’s shelf-life. This means that hydrogens are added to the carbon chain, making an unsaturated fat (good fat) into a saturated fat (bad fat). Still, trans fats are much more unhealthy than saturated fats due to the body’s inability to properly process them because they are man-made. Therefore, consuming trans fats is much more harmful than consuming just plain saturated fats.
In 2006, food companies were mandated to include the amount of trans fat present in their product on the label. Due to labeling laws, companies can claim to have 0 grams trans fats even if trans fats are present. They are allowed to claim 0 grams when there are less than 0.5 grams per serving. So if 3-4 servings are consumed, one can eat 1.5-2 grams of trans fats. This may seem like a small amount, but this is all it may take to have negative health effects.
The best way to know for sure if a food has trans fat is to read the ingredient label. Look for the words “hydrogenated” or “partially hydrogenated” in front of added oils. This is an absolute indication that the food has trans fats and should be completely avoided.
Fat and Weight Loss
Now that we know which fats are good, which are bad, and which are evil, it is time to answer the question: “Can eating good fats help with weight loss?” The answer is “No.”
Fat provides 9 calories per gram no matter the type of fat. When it comes to weight loss, total number of calories consumed is what is important. This means that 100 calories from butter will have the same effect on your weight as 100 calories from olive oil. However, the butter can have very harmful effects on your health, whereas the olive oil can have very positive effects whether you are overweight, underweight, or just right
Conclusion:
To try to over simplify the complex topic of good fats versus bad fats and healthy weights versus healthy bodies, I will conclude this article in bullet form.
1. For optimal health:
2. For weight loss:
References:
“Saturated fat.” 9 April 2009. Wikipedia.org 9 April 2009. http://en.wikipedia.org/wiki/Saturated_fat.
Hawkins EB, Ehrlich SD. 1 May 2007. Omega-3 Fatty Acids. UNM.edu. 30 Mar. 2009. http://www.umm.edu/altmed/articles/omega-3-000316.htm.
Hawkins EB, Ehrlich SD. 1 May 2007. Omega-6 Fatty Acids. UNM.edu 30 Mar. 2009. http://www.umm.edu/altmed/articles/omega-6-000317.htm.
Robinson CH, Weigley ES, Mueller DH. Basic Nutrition and Diet Therapy, 7th edition. 1993, New York: Macmillan.
Kris-Etherton PM. AHA Science Advisory: Monounsaturated Fatty Acids and Risk of Cardiovascular disease. J of Nutrition. 1999;129:2280-2284.
“Food Labeling: trans Fatty Acids in Nutrition Labeling, Nutrient Content Claims, and Health Claims Small Entity Compliance Guide.” 11 July 2003. FDA.gov. 9 April 2009. http://vm.cfsan.fda.gov/~dms/transgui.html.
Post new comment