Good fats? Bad fats? How do you tell the difference?
Updated: Jun 14
Once upon a time, eating fat was considered very, very bad. Food labels used the words "fat free" and "low fat" to entice consumers to try foods that might or might not have been actually healthier. The food pyramid had fats at the very top- to be used in the smallest portions and only sparingly. The thought was that if you eat too much fat it will make you fat, which to a novice makes perfect sense.
In the 1960's fats were given a bad reputation for causing obesity and heart disease. As it later turned out, a lot of the studies pointing at fat were actually funded by the sugar industry. Now things are more confusing. Sugar is much more of a villain in America's food system, but what about fat? Is it safe to eat now?
The answer is more complex than I once thought. It turns out there are different types of fats- some are good for you and some aren't. "Fat" is shorthand for fatty acid, and fats can occur in both plants and animals. Animal fat is easy to spot if you've ever had a steak, but plant fats are harder to notice. Plant fats are usually found in nuts, seeds, and fruits a variety of vegetation.
So what are the bad fats? Lets start with the worst one- trans fats. These types of fats are known to raise cholesterol levels and raise levels of inflammation in the body. Both of these conditions are linked to stroke, diabetes, and the number 1 killer in the US- heart disease. Nutritionists caution us to not eat any of these fats.
What foods contain trans fats? Sadly, many of the good ones. Here is the list from Web MD:
Baked goods, such as cakes, cookies and pies
Refrigerated dough, such as biscuits and rolls
Fried foods, including french fries, doughnuts and fried chicken
Nondairy coffee creamer
And just because there's a zero on the trans fat line of the food label, any food can contain up to 0.5 grams of trans fat and still report zero. Look for the words "partially hydrogenated vegetable oil" on the list of ingredients. If it's there, at least some trans fat is there too.
Next on the list of fats is saturated fats. These fats are normally found in meat and dairy products as they mostly come from animals. They are not thought to be as dangerous as trans fats, but from what I can tell we need to tread lightly on consuming these fats. Saturated fats are found in many products and have been shown to increase cholesterol levels. Once your bad (LDL) cholesterol gets high enough, blockages can start to form in your arteries.
Foods high in saturated fats include red meat, dark poultry meat, whole milk and most dairy products, coconut oil, and many baked goods like doughnuts and cookies. How much saturated fat is okay to eat per day? Guidance is for 7% to 10% of your total calories. Thats about 20 grams per day per the American Heart Association for a 2000 calorie diet.(Business Insider clocks the American average at nearly 3600 calories per day!)
Now we come to the healthy fats. Yes, it really is a thing, and of course they all come from plants. The two types are polyunsaturated fats and monounsaturated fats. Monounsaturated fats are found to help lower cholesterol and are found in avocados, nuts, and the star of the Mediterranean diet- olive oil. Studies that showed how Mediterranean countries like Italy and Greece had much lower heart disease rates because of their consumption of olive oils have made that oil a preferred oil for many nutritionists and dieters.
Polyunsaturated fats can be found in vegetable oils like canola, corn, and safflower oils, as well as seeds like sunflower seeds. Many foods have both types of healthy fats. Polyunsaturated fats are also called "essential fats" because the human body can't manufacture them on its own. These fats are used to build cell membranes and nerve coverings, so it's every diet needs to contain these to maintain health.
So healthy fats can actually be healthy, but only if taken in the proper proportions. Fats contain twice as many calories (9) per gram as protein or carbohydrates. So overdoing even the healthiest fats will still make you obese.
There's one more aspect of the fat debate that got lost in the early days, and that requires a deeper dive into polyunsaturated fats. It turns out there are two types of this fat as well- omega 3 and omega-6. I won't bore you with the chemical distinction, but the physical distinction is substantial. Omega-6 fats are more plentiful, found in many common cooking oils like soybean, canola, and sunflower oil, as well as nuts and seeds. According to Web MD, omega-6 foods can be unhealthy, especially in the quantities found in the standard American diet. They've been linked to heart disease, blood clots, and high blood pressure.
In contrast omega-3 fats are something of a wonder drug. These are mostly found in fish and seafood, which is why fish oil is such a popular supplement. Omega-3's have been studied extensively, and have been linked to improvements in heart disease, bone health, depression and anxiety, sleep, fetal development, Alzheimers and dementia, and even as a preventative for cancer. Whether all of these claims are true or not, if at least some of them are correct this is something everyone should be including in their diets.
One problem is that fish, unless dipped in fattening breading or doused with rich sauces, doesn't taste very good for many of us. Americans aren't know as big seafood eaters, instead choosing to go for meats and grains. Eating the real thing is the best way to get omega-3's, but fish oil capsules may be a workaround, though studies are not plentiful on their benefits. Since many foods have both omega-6 and omega-3, look for the ratio between the two to judge the benefits. The ideal ratio is 4:1, though for most of the standard American diet the ratio is more like 25:1 or higher.
So there you have it. Fats can be good. Or bad. Like with most of the dietary world, it's complicated. Hopefully I've simplified it a bit here.
Weight loss tip #11- Trans fats BAD- omega-3's GOOD. Plan your meals accordingly.