February 7, 2018

The skinny on saturated fat

Saturated fat, unsaturated fat, trans fat ... it can be hard to keep them all straight, much less know which ones you should keep off your plate. And it doesn’t help when experts give conflicting advice on what you should or shouldn’t eat.

So what’s the difference between all those fats?

“In general, saturated fat is abundant in animals — think meat, milk, butter and cheese — while unsaturated fat is abundant in plant fats — think avocado, nuts and oils,” said Alicia Bosscher, MPH, RD, CD, a clinical nutritionist in UW Health Preventive Cardiology. “But there are many exceptions, like salmon, which has mostly unsaturated omega-3 fat, or coconut oil, which is mostly saturated fat.”

Trans fat, considered the worst of the three, is mostly found in partially hydrogenated oils, where liquid unsaturated fat is turned into a solid by adding hydrogen, primarily to increase shelf life and save costs.

Though conventional wisdom says that eating too many foods high in saturated fat can lead to clogged arteries, some recent studies have questioned whether saturated fat is linked to heart disease.

“The latest research is confusing, even to me, a registered dietitian,” Bosscher said. “I think it’s confusing because we don’t have a rich library of large, randomized control trials. Instead, we have a few studies that say coconut oil, which is rich in saturated fat, is really not so bad, and a few studies that say it’s actually terrible.

"From my perspective, the problem is that we’re looking at populations that eat very differently than the typical American eats. These populations eat a lot of saturated fat, but they don’t eat a lot of refined grains and sugar like the typical American. Add to that the problem that it’s very hard to conduct detailed nutrition studies because we as humans are so bad at recalling what we ate yesterday, let alone remembering what we ate two weeks ago.”

Bosscher sees sugar and trans fat as the greater dietary villains. “But that doesn’t mean that the amount of saturated fat in your diet doesn’t matter,” she said.

The American Heart Association continues to recommend that people limit consumption of saturated fat, and patients with high cholesterol should be especially mindful of saturated fat and its effect on low-density lipoprotein, or “bad” cholesterol.

Keep saturated fat in check

Here are Bosscher’s tips for keeping saturated fat in check:

Consider the big picture

“My bottom line about saturated fat is this: how much you should eat depends on what the rest of your diet looks like,” Bosscher said. “For example, I drink whole milk, which has a lot more saturated fat and total fat than skim, 1% or 2% milk. But I also try to eat lots of fruits, vegetables, whole grains, nuts and seeds every day, while minimizing how much processed stuff, sugar-sweetened drinks and desserts I eat.”

Don’t try to cut all fat

“The studies seem pretty clear that if you cut out all fat from your diet and replace it with refined carbohydrates like white bread or sugar, you’re really not doing yourself a favor,” Bosscher said.

And not all fatty foods are “bad”: There are many nutritious foods that contain both saturated and unsaturated fats. “Foods like salmon, olive oil, almonds and avocados are not only allowed, but encouraged in a heart-healthy diet,” she said. However, you should steer clear of trans fat whenever possible.

Add variety to your plate

Make sure you’re filling up on the good stuff.

“If you’re prioritizing minimally processed foods that tend to have loads of healthy fiber and minimal salt and sugar, I bet you’ll have a hard time overeating on foods that have a lot of saturated fat,” Bosscher said. “For example, if you pack a picnic of just cheese and crackers, you’re going to need to eat a lot of cheese and crackers to feel satisfied. But if you pack whole grain crackers, some fruits, vegetables, olives and hummus along with the cheese and crackers, you’ll feel content with a much smaller amount of cheese because of all the fiber in the other foods.”

Think positively

“Don’t think about all the foods you can no longer eat. Instead, think about what you can add to your diet to help reduce your portions of foods that are higher in saturated fat,” she said. “For example, could you switch from two slices of white bread with butter to one slice of whole wheat bread with peanut butter? Or instead of having tortilla chips with cheese dip, maybe serve a smaller amount of cheese dip with salsa mixed in.”

Keep track

If you’re the sort of person who likes to scrutinize labels and track the numbers, Bosscher recommends trying to limit yourself to 10-15 grams of saturated fat per day. But if you don’t have a medical problem like high cholesterol, it’s fine to ignore the numbers and simply strive for healthier food substitutions.

Advice on types of fats

Unsaturated fat

  • Should you avoid it? No — these are the “good” fats

  • Examples: Fatty fish like salmon, olive and canola oils, nuts, olives, flax and chia seeds and avocados

Saturated fat

  • Should you avoid it? OK in moderation and as part of a balanced diet

  • Examples: Meat, milk, butter, cheese, palm oil and coconut oil

Trans fat

  • Should you avoid it? Whenever possible

  • Examples: Partially hydrogenated oils found in stick margarine, some fried and fast foods, frosting and sprinkles, microwave popcorn and many other packaged snacks foods