Making Sense of the Science of Fat


This piece, originally published at, is a guest perspective by nutrition and diet expert Bonnie Taub-Dix and is reprinted with permission. 

Fat has a bad reputation. There are many reasons for this, but one could say the nutrient’s PR crisis dates back to January 13, 1961. That week, the cover of TIME magazine featured scientist Ancel Keys, known for his studies relating to the impact of different types of fats on health. Although his focus was on the risks of consuming saturated fats, most fats at that time, including healthier types, were ostracized and this disdain was carried through the next few decades. Food manufacturers ran with the notion that fat should be ditched from foods (particularly in snack foods) and sugar was swapped in its place to compensate for the flavor loss.


Consumers ate up the idea of “fat-free” products with the mistaken notion that these foods might free them from their own body fat. The words were magnetic and presumed to be synonymous with “calorie-free,” yet here’s where “free” became costly. An overconsumption of sugary foods resulted in wider waistlines—obesity levels climbed, since these products still contributed a significant amount of excessive calories. Although consuming fat-reduced items can help lower cholesterol, it can also cause levels of a blood lipid called triglyceride to soar, since the body converts the extra calories from sugar into fat, which is stored by the body and can cling to artery walls, increasing risk of heart attack and stroke.

At a palatal level, the soothing taste and creamy texture of fats went missing, leading to an unsatisfied feeling after the meal or snack was done. The perceived ability to consume large portions superseded the enjoyment and attention that a more mindful eating approach (smaller quantity, but better quality) would otherwise welcome.

On the more recent June 23, 2014, cover of TIME depicting a swirl of butter, we see a very different picture than in the past. Today the question of whether butter is better has been raised along with the thoughts that saturated fats may not be as bad as believed, that sugar may be the culprit when it comes to heart disease and other maladies, and that the cholesterol you eat doesn’t necessarily translate into the cholesterol in your blood. That change of heart is a lot for consumers to swallow.

For our fat-phobic nation, inviting fat back to the plate continues to be perplexing. Data from the International Food Information Council (IFIC) Foundation 2015 Food & Health Survey revealed that 30 percent of Americans report limiting or avoiding mono- and polyunsaturated fatty acids, the healthful types people should be consuming more of, not abstaining from. Only 7 percent report actively seeking out mono- and polyunsaturated fats in their diet, while conversely, TV cooking shows regard saturated fats such as coconut oil, butter, and bacon, as if they were super-foods.

Overall, consumers are realizing that fat is an important component of the diet, particularly fats with benefits, and few would argue that foods that contain fat taste better. So let’s take a closer look at the lipids:

Unsaturated fatty acids are not “saturated” with hydrogen atoms and typically liquid at room temperature. Two subsets of unsaturated fats are mono- and polyunsaturated fatty acids. These types of fat are found in plant and vegetable sources such as cooking oils (e.g., olive, canola, soybean), avocado, nuts, seeds, peanuts, and certain seafood.

Monounsaturated fats (omega 9) may help lower LDL (bad) cholesterol, maintain HDL (good) cholesterol levels, and improve insulin sensitivity. Monounsaturated fats are often liquid at room temperature as found in oils, but they are also found in avocado and nuts. Polyunsaturated fats, when replacing saturated and trans fats in the diet, can reduce total and LDL cholesterol in the body.

Polyunsaturated fats (omega 6) may also improve insulin sensitivity. These fats are found in oils such as sunflower, safflower, sesame, and corn oils. Omega-3 fats are unsaturated fatty acids that occur mainly in fish as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). Alpha-linolenic acid (ALA), also an omega-3 fatty acid, is found in plant sources such as nuts, seeds, and oils. Science shows benefits from the consumption of omega-3’s include reducing triglyceride levels; reducing symptoms of rheumatoid arthritis, ADHD, and depression; and assisting in visual and cognitive development in infants.

Saturated fatty acids are “saturated” with hydrogen atoms and typically solid when at room temperature. These types of fat are mostly found in animal products (red meat and full-fat dairy products), fully hydrogenated oils, and tropical oils (e.g., palm and coconut oil). Studies have shown that saturated fats may increase LDL and HDL cholesterol in the body. Recent research creates questions as to whether or not saturated fats are harmful; however, they have not been shown to be significantly beneficial.

Trans fats are technically unsaturated. They are made through an industrial process that adds hydrogen to vegetable oil. As a result, they are solid at room temperature and act more like saturated fats in the sense that they may raise total and LDL (bad) cholesterol, and triglycerides. These fats are commonly present in certain stick margarines and pastries. Try to avoid foods containing these fats, and look for the words “hydrogenated” and “partially-hydrogenated” fats on food labels to help identify where trans fats may be lurking.

The bottom line is that it might be beneficial to find fats in the form of monounsaturated and polyunsaturated fats by adding avocado on your sandwich, oil on your salad, and nuts on your breakfast cereal. Fats such as these add flavor and they keep us satisfied.

The amount of total fat in your diet should be around 25 to 30 percent of your total caloric intake. Based upon 2,000 calories a day (keeping in mind that if you’re very active, you may need more calories while others attempting to lose weight may need less), that would translate as 55 to 65 grams of total fat a day. Remember to keep a keen eye on portions, since one-fifth of an avocado or a tablespoon of nuts contains around 5 grams of fat each … these numbers add up quickly!

If you enjoy foods that contain saturated fats, such as meat and tropical oils like coconut oil, be mindful to choose reasonable amounts. The Dietary Guidelines for Americans suggest that we try to limit saturated fats to no more than 10 percent of our daily intake. In terms that are easier to take to the supermarket, that means if you are consuming a diet that is around 2,000 calories a day, you should not be eating more than around 22 grams of saturated fat a day. Be sure to check food labels and serving sizes to determine how much you’re really getting in the foods you purchase.

And for those foods that contain hydrogenated and partially hydrogenated (trans) fats nestled within certain donuts, pastries, and spreads, it would be best to just say, “No thanks.”

Most importantly, if you’re going to include healthier types of fats with your meals, you need to remember that they should take the place of less healthy options. If not, then adding fats of any type could also add unwanted pounds.