Unless you’ve been living in a nutrition science bubble, you know this story well: A few decades ago, a low-fat craze exploded in the food industry. Margarine became the go-to spread, skim milk became the drink of choice, and nuts and avocados were shunned as being sky-high in unhealthy fat.
However, newer thinking in nutrition research has shown that there is such a thing as healthy fats, known as monounsaturated and polyunsaturated fats. These are the fats found in fish (like salmon) and plant-based foods (like walnuts, olives, and avocado). And nutritionists want you to eat more of these good fats.
These healthy fats lower LDL (bad cholesterol) and increase HDL (good cholesterol), which reduces the risk of heart disease. That’s why people refer to nuts and fish as “heart-healthy” foods: They may protect the heart from serious conditions.
Omega-3 fats, a type of healthy polyunsaturated fat, cannot be made in the body and must be obtained from food. These good fats are found in foods like fish, walnuts, and seeds, like hemp, flax, chia, and sesame. (Make this post-workout smoothie bowl for a dose of good fats from pistachios.)
But it’s all too easy to eat too many bad (unsaturated and trans) fats that can have the opposite effect on your health. You might not know this, but your body has the ability to synthesize saturated fats, so you don’t need to eat large amounts. Saturated fats raise bad cholesterol levels (LDL).
Foods high in saturated fats tend to be animal products, like beef, poultry, and full-fat dairy. While some cuts of beef or chicken may be less fatty than others (and dairy products are available in skim or low-fat versions), animal products still contain higher amounts of bad cholesterol.
The most unhealthy fat in your diet is trans fat. In fact, trans fat is so dangerous that some countries around the world have banned its use in food production. Trans fat is used to increase shelf life and create and maintain a consistent texture in foods, so it can be common in processed foods like boxed mac and cheese, margarine, cake mixes, and canned doughs, to name a few.
Since 2006, all nutrition labels in the United States must now include a line for trans fat, but here’s the catch: If the product contains less than 0.5 grams per serving, the nutritional label can say it contains “0 g of trans fat.”
This is problematic for a couple reasons. First of all, the food manufacturer can easily manipulate the suggested serving size until the trans fat number falls below 0.5 grams, even if that serving size is unrealistic. Second of all—let’s be honest—it’s common to consume more than one serving of these types of foods, especially if the serving size is already tiny. That means you might be eating unhealthy levels of trans fat without even knowing it.
A smarter way to scan your food for unhealthy trans fat amounts: Check the ingredients label. Avoid ingredients such as “shortening” or “partially hydrogenated vegetable oil.” These are notorious sources of trans fat. An even better option is to skip the boxed and bagged grocery items and stick to fresh, whole ingredients.