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Sunday
Mar272011

Myth Busting: Fat

Written by: Tom Nikkola – Director of Nutrition & Weight Management

Fat. For 50-60 years, this three letter word has been perceived as more of a four-letter word. In fact, it’s possible our fear of fat can have detrimental effects on our health because we misguidedly avoid its consumption. The following are some myths about dietary fat and what research the actually says.

Saturated Fat Raises Heart Disease Risk

The perception that saturated fat intake leads to heart disease has been pervasive for a few decades. It’s true that saturated fat increases LDL cholesterol. It also increases HDL cholesterol. HDL cholesterol is considered the “good” fat, and generally, the higher our HDL levels, the better. LDL cholesterol has been universally labeled as “bad.” Usually, when blood testing is done to check lipid profiles, only the total LDL cholesterol is reported, which can be quite misleading. The LDL particle can be more important than the total amount, as large, fluffy LDL cholesterol, increased with saturated fat intake, does not appear to play as much of a role in the development of heart disease as the small, dense particles, increased with the overconsumption of carbohydrates. In fact, the low-fat diets they follow to reduce cholesterol may actually increase the development of very-low density lipoprotein (VLDL) cholesterol, which can have a significant effect on heart disease risk.[i]

Along with saturated fat, dietary cholesterol has gotten a bad reputation as well. However, dietary cholesterol appears to have little to no effect on blood cholesterol levels in the body. If the body does not receive sufficient cholesterol from the diet, it makes its own. This is why many people who attempt to reduce their consumption see little change in their cholesterol levels. It can be confusing because statins, targeted at those who are at an increased risk of heart disease, reduce LDL cholesterol. Many assumed the LDL-lowering effect was why they reduced heart disease risk, but more recently, experts see the benefits of statins coming from the reduction of inflammation, not necessarily the LDL-lowering effects.

So what exactly does research show about the effects of fat and saturated fat on heart disease risk and its health risk markers? In Why We Get Fat: And What to Do About It, Gary Taubes compares studies of those following low-fat diets to those who ate mostly fat and protein and found the latter: [ii]

Further, current research on saturated fat in the American Journal of Clinical Nutrition states, “substituting total carbohydrate for SFAs (saturated fatty acids) is associated with no or a moderately higher risk of CHD (coronary heart disease).” In fact, the authors maintain there is “no clear relation” between saturated fat intake and cardiovascular disease.[iii]

Let’s make one further important distinction: Saturated fats are not the same as trans fats. Trans fats can raise LDL cholesterol while lowering HDL levels, which is always a problem — and worth of an entirely separate discussion.

All Vegetable Oils are Healthy

Paralleling the promotion of reduced-saturated fat diets, consumption of vegetable oils has increased steadily. These include industrial seed oils such as corn oil and soybean oil. Their perceived health benefits are based on the fact they have less saturated fat compared with naturally-occurring animal fats like butter.

However, they also contain a pro-inflammatory fatty acid called omega-6. The use of vegetable oils has caused a significant increase in the ratio of omega-6 and omega-3 fatty acids in our diet. Ideally, our diets should have a ratio of 1:1 to 3:1 omega-6 to omega-3 fatty acids. The average American today has a ratio closer to 20:1 omega-6 to omega-3!

Some researchers have hypothesized the high amounts of omega-6 fatty acids are adipogenic, meaning they promote the growth of stored fat tissue. In animal studies, this increase in omega-6 fatty acids has been shown to have a significant effect on the development of obesity.[iv]

In another research study, researchers fed mice a diet containing a higher than normal amount of omega-6, in the form of linoleic acid. They kept the total calorie intake the same and bred four generations of mice. Though each generation was technically the same, and they were fed the same amount of calories, each generation became more overweight and had increasing levels of circulating insulin.

Vegetable oils are found in most processed foods, and with people’s fear of saturated fat, they often use them for cooking in place of butter or coconut oil. For cooking, the evidence shows that butter and coconut are likely healthier. For more ideas on what fats and oils to use in your diet, you can refer to our Eat Well. Live Well. e-book.

Lumping all vegetable oils together and considering them healthy is not accurate. There are some vegetable-based oils like olive oil which can play a role in a healthy diet, but not all types should be consumed on a regular basis.

If You Eat Fat, You’ll Get Fat

If you were to review the way food packages are created, you’d certainly think that reducing fat in the diet helps with weight loss. This idea originally stemmed from the fact that a gram of fat has more than twice as many calories as carbohydrate or protein. If we were to eat the same amount of food by weight every day, limiting fat would help in reducing calories. But that isn’t how we eat.

And we already know managing weight involves more than just counting calories. The evidence in studies using fat reduction to lose weight doesn’t show a benefit when energy intake is consistent. In fact, for those on a reduced-calorie diet, higher fat diets have been shown to lead to greater weight loss.[v]

There are a variety of possible reasons why reducing fat intake rarely leads to long-term weight reduction. The most likely is that when people attempt to eat more low-fat foods, they end up eating high-carb, low-fat, low-protein foods. This sets them up for a blood-sugar rollercoaster, where they crave more carbohydrates all day long. While they are eating them, they also keep their blood sugar and insulin levels high, which prevents body fat from being burned as energy. Finally, their overall calorie intake is often higher eating these low-fat foods than if they were to include more protein and fat in their diet.

A 2009 study of almost 90,000 people revealed “no significant association between the amount or type of dietary fat and subsequent weight change.”[vi] Though vegetable fats may increase the rate of obesity as mentioned above, population studies show that fat in the diet does not lead to weight gain.

The average American has reduced their fat intake more and more over the past few decades, and the rate of obesity has been increasing steadily during that time. Whether the growing rate of obesity come from a reduction in fat and protein, an increase in carbohydrate, or both, it is difficult to conclude. As supported by research, eating less fat has not been shown to prevent weight gain or led to weight loss.

Summary

Like the trends in carbohydrate and protein consumption, the amount and types of fat we eat has changed significantly in the past 100 years. Fat plays a critical role in our diet, and like protein, certain fats are considered essential in our diet. Fatty acids play important roles in the healthy functioning of our bodies’ cells, the creation of needed cholesterol, development of hormones and they provide a great energy source that does not increase insulin levels.

This article is not intended for the treatment or prevention of disease, nor as a substitute for medical treatment, nor as an alternative to medical advice. Use of recommendations in this and other articles is at the choice and risk of the reader.

If you would like to include some fat myths of your own below that weren’t included, please continue the discussion or ask questions in the comments section below.

See also: Myth Busting: Protein

See also: Myth Busting: Carbohydrates


[i] Foster, et al. Weight and Metabolic Outcomes After 2 Years on a Low-Carbohydrate Versus Low-Fat Diet: A Randomized Trial. Ann Int Med. 2010:153(3):147-157

[ii] Gary Taubes. Why We Get Fat: And What to Do About It. 2011. Alfred A Knopf, Random House Inc. New York, NY

[iii] Astrup A, Dyerberg J, Elwood P, et al. The role of reducing intakes of saturated fat in the prevention of cardiovascular disease: where does the evidence stand in 2010? Am J Clin Nutr. 2011;92(4):684-688

[iv] Ailhaud G. n-6 Fatty acids and adipogenesis. Scan J Food & Nut. 2006;50(52):17-20

[v] Shikany JM, Vaughan LK, Baskin ML, Cope MB, Hill JO, Allison DB. Is Dietary Fat “Fattening”? A Comprehensive Research Synthesis. Crit Rev Food Sci & Nut. 2010;50(8):699-715

[vi] Forouhi NG, et al. Dietary fat intake and subsequent weight change in adults: results from the European Prospective Investigation into Cancer and Nutrition cohorts. Am J Clin Nutr. 2009;90(6):1632-1641

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Reader Comments (1)

Some types of fats can either increase the size and/or number of fat cells. It's important to consider the thermal properties of cooking oils. For example, cocunut oil and olive oil are high-temperature cooking oils. Heat (energy) can change the properties of cooking oils. Cooking with heat can also change the nutritional value of foods as well.

According to Dr. Eric Serrano, corn oil, which is widely used, is hazardous to your health. Especially when cooking with corn oil at high temperatures.

March 28, 2011 | Unregistered CommenterNate

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