I confess. The profession of dietetics has been wrong about the detrimental effects of fat and we have been slow to change our message. The great “fear of fat” began in the 1970s when Ancel Keys published a study where he compared heart disease risk between countries based on their saturated fat intake (an observational study, which is a weak design). This study caused a huge stir, saturated fat became the enemy, and the margarine business boomed! However, as years progressed, little research actually backed up the claim that fat was bad, but it was too late. The low fat diet trend was here to stay. Have we seen a drastic decrease in the rate of heart disease? Most definitely not. It is still the most leading cause of death in this country. How about obesity? Hmm… it appears we didn’t fix that by cutting fat out of our diet either! Over a third of the US adult population (35.7%) are obese and another 33.3% are overweight (CDC, 2009-2010). Yikes!
Let’s have an honest discussion about fat, shall we?
What’s in the Names?
I am going to get a little science-y on you for a second; just hang in there! When we talk about fat in the diet, there are often other adjectives that come up like: saturated, polyunsaturated, trans, essential, etc. Where do these terms come from? It all has to do with the chemical structure of the carbon chains that make up a fat. If you look at the picture below, you can see the difference between the types of fats depends on whether there is a double bond between any of the carbons (ie. double lines in the chain) as well as the shape. Saturated fats have no double bonds and are hard at room temperature (ie. butter). Unsaturated fats have one (monounsaturated) or more (polyunsaturated) double bonds and will be liquid at room temperature (vegetable oil). The shape of these unsaturated fats is important too! Natural unsaturated fats usually have a ‘cis’ shape (ie. U-shape). Trans fats (ie. margarine), created by manufacturers to turn a liquid unsaturated fat into a solid causes the shape to bend into the ‘trans’ shape (ie. straight). The cis vs. trans shape makes a huge impact on health.
Why is Fat Good for Me?
Fat is an essential part of the diet! It not only makes food taste better (hello, butter!) but it also helps you feel more satisfied with a meal since it is digested more slowly than carbohydrates and protein. Yes, it is more calorically dense at 9 calories/gram vs. 4 calories/gram in carbohydrates and protein; but we are learning that the calories in vs. calories out equation isn’t all that it was purported to be. Simply substituting lower calorie carbohydrates in your diet for fat doesn’t fix the problem, but may actually put you more at risk for chronic diseases. Let’s take a loot at a few reasons you should incorporate fat into your diet:
- When you use full-fat salad dressing on a salad, you absorb the antioxidants in the vegetables better. (Plus, did you know, they add a lot of starch and sugar to low fat dressings?!) (Source)
- Replacing fat in your diet with carbohydrates (especially refined carbs) may have detrimental health effects such as increased risk of diabetes, heart disease, and obesity. (Source)
- If you replace some of the saturated fats (ie. meat, butter) in your diet with polyunsaturated fats (vegetable oils, nuts) instead, it may help reduce cardiovascular disease risk. (Source)
- Avoid trans fat whenever possible as it increases your risk of heart and other chronic disease by damaging arteries through inflammations. (Source)
- Omega 3 fatty acids have numerous health benefits including decreasing inflammation and blood fat (triglyceride) levels, possibly alleviate depression and lower risk of Alzheimer’s. (Source)
- Americans typically get a lot of Omega 6 fatty acid in their diet, which some studies indicate may contribute to chronic disease. A good ratio of Omega 6 to Omega 3 foods in your diet may help normalize this risk. (Source)
- A recent meta-analysis of cohort studies (which provide strong evidence) indicated that there was no link between saturated fat and heart disease risk. (Source)
Translating This Into Food!
Enough research and chemistry, let’s talk about food! Here is a simplified list of foods.
Here’s the way I approach it. I avoid those foods high in trans fat whenever possible, which is relatively easy to do if you don’t eat a lot of packaged or fast foods. For the rest, I try to add a variety of these different high fat foods into my day. I really have to make an effort to incorporate foods high in Omega-3 at least a couple of times a week – usually in the form of tuna, salmon, or walnuts – since there are not a lot of foods high in this fat and it has so many benefits! I used to steer clear of whole fat dairy, but no more! I made the switch about 2 years ago and guess what? I didn’t gain any wait for the change!
So, what do you think? Are you ready to stop worrying about fat and throw out all those “low fat” products?