I like good fats and I cannot lie: A guide to "healthy" fats
It seems like there’s always some type of debate going on in the nutrition world about the role of fat in a healthy diet.
First, low-fat was the way to go. This led to the development of sketchy fat substitutes like “I Can’t Believe It’s Not Butter” (I can believe it) or Olestra (anal leakage for your Friday night?), and the injection of excessive amounts of sugar and salt into “low fat” foods to make them taste good and pass as edible.
Then, the pendulum swung to the opposite side of the spectrum with the Paleo and other ancestral health movements, which promoted fat as the new solution to all of our diet-related problems. Hungry? Need to lose weight? Want more energy? Just add butter to it! Things like Bulletproof Coffee became the new craze, and bacon became a “health food.”
We’re now living in this awkward new world where it seems like things are just plain confusing. Some people remain stuck in the low-fat mindset while others pile bacon, butter, and olive oil on top of everything.
For better or worse, we think there’s logical (and scientific) flaws with both the low-fat and high-fat evangelist approaches. Consider:
The body needs fats for everything from hormone production to maintaining cell membrane to proper nervous system function. There are many types of fatty acids that the body cannot make on its own but are vital to survival (e.g., essential fatty acids omega 3’s and omega 6’s). Fats also play a key role in satiety and trigger the brain to tell us that we are full. Therefore, by this logic, a low-fat approach can’t be right, can it?
Conversely, oils and fats are a relatively new development in human history. Some evidence shows that humans started milling grains before they began pressing olives for olive oil. And the development of the type of agriculture that would support mass consumption of nuts and seeds came much later. So are commonly touted “paleo” foods like extra virgin olive oil and almonds really consistent with an ancestral diet approach?
But don't give up hope! For us, the best approach is, as always, nuanced, and somewhere in the middle. We think the best place to start is by understanding the basic science of fats.
Fats: A biochemistry lesson
Before we get into the nuts (literally) and bolts of fat consumption, we think it’s helpful to review the biochemistry of fats. Fats, also called lipids, are compounds made up of chains of fatty acids. Different types of fats have different combinations of various fatty acids. And as is almost always the case with the body, structure dictates function. Each of these lipid and fatty acid molecules has a different role to play in the body. Once we understand the biochemistry of lipids, we can then build back up into recommendations for consumption.
So, what is a fat?
Here are some of the major roles that lipids play in the body, and why we need them:
Hormone production and composition
Nervous system function
How are lipids digested?
The body has multiple steps to digesting lipids, including:
Mouth: Digestion begins through enzymes in the saliva.
Stomach: gastric lipase. This partial digestion slows stomach emptying, which generally can help keep you fuller longer
Small intestine: Primary location of fat digestion via compounds excreted from the pancreas. The fats are emulsified by bile and broken into smaller globs. Pancreatic enzymes continue to break down fats. They are then moved out of digestive tract into lymphatic system. From lymph it goes into bloodstream.
The presence of fats in the small intestine slows motility which allows for digestion and absorption
However, it takes about 20 minutes for this process to trigger fullness
What is the difference between fat types?
You've probably heard of different types of fats. Before we label anything as "good" or "bad," we must understand its structure and function.
Saturated: The carbon chain is “saturated” with hydrogen atoms. This makes it more rigid and solid at room temperature.
Butter, coconut oil
When eaten in excess, at the exclusion of other fat types, and with high amounts of salt and/or sugar (common in many packaged foods), saturated fat intake can increase cardiovascular disease risk factors and potentially cause arterial plaque buildup. But some saturated fat intake is essential to some body functions such as hormone production.
Unsaturated fats: These are fats with one or more carbon "double bonds" in their structure which eliminates hydrogen atoms from the chain. This creates points at which the molecule can “kink” or “bend,” making it more fluid.
Monounsaturated Fats: Almonds, pecans, pumpkin seeds
Polyunsaturated Fats: Walnuts, flax, many types of fish
These fats are often labeled the "healthy fats" are an needed for many different functions in the body. Their fluidity gives them versatility and prevents them from building up as arterial plaque
Omega fatty acids are specific types of polyunsaturated fats that perform many different functions throughout the body.
Omega 6 fatty acids are prominent in the standard American diet and are less fluid. When they are not balanced by other fat types, excessive Omega 6's can create an inflammatory environment.
Omega 3 fatty acids are less prominent in the standard American diet, are more fluid, and may have anti-inflammatory properties. They are also vital to neurologic function and health.
Trans fats: A hydrogen atom is artificially added to an unsaturated fat, which straightens molecule and changes structure to reduce spoilage in processed foods. These molecules do not kink or fold. They pack tightly making it difficult to move/breakdown.
Trans fats are rarely found naturally (there are a few exceptions) and are artificially created during food processing
Overall, we recommend that most people eat a variety of different whole-foods fat sources in moderation. Our infographic outlines the different types of fats, and some of our general recommendations for fat consumption. Check it out and download it for reference.
When too much of a good thing isn’t a good thing
Fats are a great part of a balance meal or snack, but they should only be a component. From a calorie standpoint, carbohydrates and protein yield 4 kcal/gram and fat yields 9 kcal/gram. Because fats are more energy dense, it can be easy to have too much. This is a common misstep, especially for those looking for weight management. Next time you give yourself a good dose of those healthy fats, take a look at how much you are using.
1 handful of nuts or seeds: 100-200 calories vs. all of the nuts until you’re full? 800-1000+ calories
1 large avocado: 300 calories vs. ½ small avocado 75-100 calories
1 tbsp of nut butter: 100 calories vs. Putting it on literally everything: who knows
1-2 tbsp olive oil for cooking: 120 calories vs. It’s a healthy fat right?: 500-1000 calories +?
So, if I haven’t hit the nail on the head yet… MODERATION PEOPLE! Calories aren't the whole story, but if you're drowning everything in fats, you're overdoing it.
Here’s a few additional takeaways and caveats:
The research simply isn’t clear about what optimal fat intake is. There are too many variables to consider: gender, genetics, gut bacteria, activity levels, and, hormone levels. Many of those factors themselves are in constant flux. Because there is no “right” answer, we think the best approach is moderation.
The presence of almost any disease or disease risk factor might modify our fat recommendations for you. The information presented in the infographic are general tips for a healthy population. In particular, fat recommendations are dramatically different for patients with cardiovascular disease, hypertension, elevated triglycerides, diabetes, pancreatic disease, gallbladder disease, and many other conditions. If you have any of these conditions or risk factors, talk to a qualified health professional, ideally a Registered Dietitian along with your primary care physician, to determine what is best for you.
A main reason for moderation is that fats are very energy dense (9 calories / gram vs. 4 cals/gram for protein and carbs).
In the absence of disease, the trouble is not necessarily with fat consumption itself, but either:
A) Fat consumption in the presence of high carbohydrate and sugar intakes. This is common in commercialized processed foods: fat, sugar, and salt taste great! But, together they make it is easy to get into a caloric / energy surplus and potentially contribute to an overall inflammatory state
B) Consumption of fat to the exclusion of adequate carbohydrate and protein intake. This often your low-carb, bacon-is-a-health-food advocate. While high-fat, low-carb diets work for some people, they don’t work for everyone, particularly most females, and high-volume endurance athletes (yes, there is some debate on this… a topic for another post).
Saturated fat has been shown to be okay WHEN: There are no cardiac disease risk factors, refined carbohydrate intake is low, and there is a balance of unsaturated fat intake as well.
Polyunsaturated fats can help lower “bad” HDL cholesterol when eaten IN PLACE OF saturated or trans fats
Again, in the absence of a clear consensus on appropriate lipid intake, we recommend a balance intake of saturated, mono-, and polyunsaturated fats.
Lastly, make sure that the majority of your fats are coming from whole foods. Some of these include: avocados, nuts, seeds, cold-water fish, and whole coconuts. Whole food sources offer a variety of nutrients including fiber, protein, vitamins and minerals.
Concerned or confused about fats, carbs, and proteins? Not sure if your current nutritional habits are helping you meet your goals? We’re here to help. Click the button below to schedule a FREE 15-minute strategy session with our Registered Dietitian to develop a plan to meet your goals.