All about "macros" (part 3/3. Fat!)

I saved the best macronutrient for last - fat! There's a lot of confusion about fat and its role in our health. Read on to learn more. 

Are you behind on your reading? Be sure to check out part 1 (carbs) and part 2 (protein) .

As with the other macros, when we talk about dietary fat, we're really looking at categories and chemistry. There are 4 main types of fat based on chemistry: 

• Saturated fat
• Trans fat
• Monounsaturated fat
• Polyunsaturated fat 

The terms saturated vs unsaturated fat refers to their chemical structures. All fats are made of smaller molecules - glycerol and fatty acids. But saturated fats tend to be saturated with hydrogen molecules whereas unsaturated fats have a double bond. This changes how the fat is processed by the body. 

What do fats do? 

The chemistry and the type of fat makes a different in how that nutrient is used by our body. All fats are turned into lipids and are later repackaged as lipoproteins to help our body: 
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• Transport, absorb, and store vitamins A, D, E, and K​
• Are a major contributor to sex hormone production and corticosteroids
• Form the outer layer of every cell on our body (aka, the phospholipid bilayer)
• Source of essential fatty acids omega 3 and omega 6 (remember, essential means our body can't make it - we have to get it from food)
• Omega 3 fatty acids reduce inflammation in the body
• Form much of the brain
• Taste amazing

We get these benefits from all fats - not just the "healthy" ones. 

Fats that we eat do NOT become body fat. Dietary fat is very dense - it has the highest energy per gram (9kcal/g) compared to carbs and protein (4 kcal/g). This is great for anyone who needs a lot of calories but has a small appetite (eg, infants, toddlers, children, athletes, older adults, people going through cancer treatments). Fats are crucial for the brain development of children and adolescents. Additionally, fat is satisfying and digests slowly which reduces our cravings for sweets.

​Fat is not the enemy. 

The only real danger of dietary fat is when we eat an imbalanced amount OR inadequate fat. That can lead to changes in cholesterol production. 

How much do I need?

In general, our bodies thrive when fats are at least 25% of our calories. For a 2000 calorie diet, that's at least 55 grams of fat per day (of any type of fat). 

Saturated fat

For heart health, the American Heart Association recommends limiting saturated fat to 5-6% of calories. That's about 11-13 grams / day. Other organizations recommend < 10% of calories from saturated fat (or 22-26 grams / day)

Polyunsaturated and Monounsaturated fat

Unsaturated fats tend to get lumped together when it comes to recommendations. Ideally these fats should make up the majority of the types of fat eaten and our bodies prefer if we eat a variety of sources.  

Trans fat

Trans fat or "partially hydrogenated oils" are terrible for our cholesterol. It's best to avoid as much as possible. ​

Most foods with dietary fat are a combination of saturated and unsaturated fats. The percentage of saturated and unsaturated fat varies. It's best if most of the fat we eat is primarily unsaturated but it's impossible (and unnecessary) to strictly avoid saturated fats. ​

Here's a closer look at the types of fat in various oils. Note that coconut oil is almost exclusively saturated fat and that canola oil has the lowest amount of saturated fat.

What should I eat? 

I don't recommend anyone start trying to count the number of grams of fat they eat each day. Additionally, just because a food is higher in saturated fat does NOT mean it needs to be avoided! The "best" choices depend on eating preferences and styles. 

In general the goals are to:

1. Avoid trans fat
2. Limit saturated fat
3. Enjoy mostly unsaturated fats

It's about balancing your overall food choices. Here are some of the most common food questions I get in clinic. 

When it comes to butter vs margarine, it depends on your overall diet. 1 T of regular butter comes in at 7 grams of saturated fat (1/2 of what you need in a day). However, if you don't eat much total saturated fat (and don't eat much butter), there's nothing wrong with regular butter. However, if you love putting that butter flavor on everything and/or want to keep other high fat animal products in your life, you may consider switching to a TRANS FAT FREE margarine. 

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First off, nuts are an excellent source of fat but not a high source or protein. Second, there are benefits to every nut. From a type of fat perspective, almonds and walnuts have higher amounts of unsaturated fats - particularly omega 3s. However, they're also more expensive making them not accessible to everyone. Don't be too quit to rule out peanuts as a great source of fat. 

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Eggs are not the demon the media makes the out to be. Eggs are low in saturated fat compared to other protein options. For more details on eggs, check out this blog post. 

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Cheese has a surprising amount of saturated fat. It's delicious and adds tremendous flavor. Often vegetarians rely on cheese for protein, but  ideally it should not make up a large percentage of the diet. 

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Whole milk or whole fat yogurt is rarely a deal breaker for a healthy diet UNLESS you're drinking more than 4 glasses a day (or the rest of your diet is very high in saturated fat). Additionally, having fat in milk allows your body to absorb more vitamin D (and calcium!). 

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Finally there's meat. All meat has saturated fat. The leaner the meat, the less saturated fat it has. In general from highest to lowest saturated fat: 

• High fat deli meats (hot dogs, bacon, sausage, pastrami, salami, brats, bologna)
• Red meat (cuts of beef)
• Pink meats (pork, goat)
• White meat (chicken, turkey, white fish)

However, keep in mind that when you fry a meat, it increases the amount of saturated fat pretty quickly!

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Coconut oil is so hot right now. Pop culture diets like Paleo treat it like a super food, but its benefits are not well researched. Coconut oil is high in saturated fat. But the chemistry / bond is different than the saturated fat found in animal products. The research is not clear whether or not that means we metabolize it differently. In general, if you want to use it, keep the amount small. 
Want more information? Check out this article on Today's Dietitian. 

Moral of the story...

Dietary fat is essential for the body and does so much for our health. It's best if we get most of our fat from plants and fish but that doesn't mean we need to avoid fat from animals - just don't go overboard.  

Stay nourished friends!