Are you confused about what to eat (and what to avoid) to optimize health, lose weight, balance your hormones and blood sugar, and/or manage a chronic condition?
If so, you’re in very good company.
It gets confusing for everyone, even the experts, sometimes!
This is where a basic understanding of the principles of functional nutrition can simplify your relationship with food, give you a road map of what to eat, and end the food and diet confusion forever.
But what is functional nutrition, and how can it be applied to individual dietary needs and nutritional philosophies?
The great thing about functional nutrition is it is 100% applicable and adaptable to anyone, regardless of your current state of health, food sensitivities, genetics, nutrition philosophy, or personal tastes.
In this guide, we’ll provide a background on functional nutrition and its core practices and share 12 simple and sensible functional nutrition principles that will help you reframe your relationship with food and dieting, starting right now.
What Is Functional Nutrition?
Like functional medicine, functional nutrition is an integrative approach to food and nutrition based on individual needs.
Unlike other diets or nutrition philosophies, functional nutrition does not ascribe to one way of eating.
Instead, it seeks to honor the specific nutritional needs of the individual, which vary from person to person based on many factors, including but not limited to:
- Genetics
- Lifestyle
- Family and medical history
- Stress
- Nutrient deficiencies or insufficiencies
- The person’s current state of health
- The presence of any chronic issues
- Activity level
- Food sensitivities
- Hormonal balance
- Blood sugar regulation
Nutrition guidelines such as carnivore, vegan, paleo, keto, and the like all have their dietary merits, but they can all become very dogmatic, unhealthy, and unbalanced.
It all depends on which foods and food combinations are chosen, the overall amount of food consumed, the time of food consumption, the person’s age and activity level, and the health needs of the person.
Remember, Oreos are technically vegan, but eating a diet of Oreos isn’t healthy.
Ultimately, a healthy diet provides optimal protein, fiber, healthy fats, and colorful produce, all within an appropriate calorie range for your body, age, state of health, genetics, and activity level.
Bottom line: Although functional nutrition has foundational principles, which we’ll discuss later, it does not dictate one particular way of eating.
Instead, functional nutritionists and therapists will seek to optimize an individual’s nutrition based on how best to nourish and support the whole person.
Functional Nutrition Honors The Link Between Genetics And Dietary Needs
As we just covered, we do not believe there is one perfect diet for everyone.
A big reason for that involves the link between genetics and dietary needs.
Our genes evolved along different migration patterns, creating a variation in genetic and epigenetic (gene modifications or adaptations) expression over hundreds of thousands of years.
Thus, depending on these factors, your individual needs will differ from your BFF’s.
This is why large population studies on nutrition and diets can be confusing and contradictory.
For example, research has shown certain groups of people from north European Celtic and African backgrounds have a genetic mutation that allows them to tolerate dairy products better than those from other cultures.1
As discussed in: Tips to Stop Sugar Cravings + A Guide to Natural Sweeteners, research has shown famines primed certain ethnic groups to become more insulin-resistant for survival. Known as the “thrifty gene” and “thrifty phenotype” hypothesis, it explains why people of some ethnicities have a lower tolerance for sugar, carbs, and alcohol.2
These are two of many examples of how our genes and evolutionary path can affect our nutritional needs.
Discovering How Your Genes Affect Your Nutritional Needs: The Role of Nutrigenomics
So, how can we know how our genes may affect our nutritional needs?
In our clinical practice, we often look at nutrigenomics to help dial in on these nuances.
Nutrigenomics is the study of how foods affect our genes and how genetic differences affect our response to food.
And yes, there is a test for this!
Our favorite test is Nutrition Genome, which you can order on your own to get a helpful nutrition baseline on what your body needs to thrive, such as individual nutrient requirements, macronutrient metabolism, meal timing, stress management, methylation, and much more.
Digging Deeper With Functional Nutrition Lab Testing
In our practice, we also order in-depth labs to assess our patients’ nutrition status, allowing us to make more individualized recommendations.
Examples of areas we may test for in functional nutrition include:
- Functional nutrient levels for things like homocysteine, B2, B12, vitamins A and D, iron/ferritin/CBC, and more
- Gut health, which impacts nutrient absorption and inflammation
- Thyroid panels, which relate directly to metabolism
- Metabolic markers like blood sugar, fasting insulin, HbA1c, uric acid, cholesterol, and more
- Food allergies and sensitivities
The exact tests depend on the individual, their presentation and symptoms, and their health goals.
Functional nutrition therapists or nutritionists often work with a functional medicine physician (in our case, that’s me! Dr. Maren) who can order more advanced labs.
What About Food Sensitivities/Tolerances?
Functional nutrition recognizes the reality of food sensitivities and intolerances in different people.
This can be a huge relief to those who have worked with more traditional dieticians or nutritionists who dismissed their concerns in this area.
Food sensitivities are highly individualized and not always obvious as they don’t present in the same way as a food allergy.
For example, we’ve worked with patients who had chronic digestive issues and others with chronic skin conditions, and they both had dairy intolerances that were contributing to their problems.
If you are struggling with chronic health or digestive issues, trying an elimination diet can be an effective and accessible way to identify trigger foods that may be causing or exacerbating your condition.
Common Food Sensitivities
The most common food sensitivities we see are:
- Gluten
- Dairy (especially cow-based dairy)
- Corn
- Soy
- Eggs
Many of our patients also benefit from temporarily eliminating or limiting refined sugar, alcohol, and sometimes caffeine.
How to Optimize Nutrition When Dealing With Food Intolerances
There are various ways to evaluate which foods (even those considered “healthy”) may not serve your body at certain times.
Working with a functional nutrition therapist or nutritionist to walk you through an elimination diet and reintroduction, for example, can eliminate the guesswork.
The great thing about an elimination diet is that many of our patients can successfully reintroduce some of these foods without problems once their underlying health issues, such as gut health, inflammation, etc., are addressed.
Unfortunately, gluten intolerance is the exception. I don’t find people can typically tolerate it again and maintain the same level of health and healing.
Learn more about the basics of elimination diets in: The Epidemic Of Food Allergies And Food Sensitivities.
Simple Guiding Functional Nutrition Principles For Healthful Eating
It’s now time to get into the meat of the article, the guiding functional nutrition principles of healthy eating.
Although functional nutrition does not ascribe to a rigid “diet” or set of rules, my team believes the following principles can help everyone improve their health.
Functional Nutrition Principle #1: Reduce Ultra-processed Foods
Buying whole foods and eating them as they are, as nature intended…with maybe some healthy fat and seasoning, is one of the best ways to support your health.
Foods come in a particular food matrix, and the more we stick to this natural form, the better we will utilize the nutrients provided by that food.
One of the easiest ways to have a good relationship with natural satiety is avoiding ultra-processed foods.
Why? Because these foods are manufactured and developed to create a bliss point.
Big Food researchers figure out the perfect amount of salt, crunch, sugar, etc., to make these foods the most desirable and hardest to stop eating (which supports sales of these foods, which is the primary goal of Big Food companies).
Think your organic, all-natural, yet processed snacks aren’t in this category?
Although there are some exceptions, the sad reality is that Big Food corporations have bought up most of the mom-and-pop organic and even regenerative snack companies.
Of course, these are definitely better choices than the more ultra-processed brands, but it’s something to be aware of.
The bottom line is to eat more whole foods, and you’ll be much healthier and more satisfied.
Functional Nutrition Principle #2: Create The “Home Team Advantage” By Cooking At Home
One of the best ways to improve health and body composition is to cook at home as often as possible.
Restaurants and chefs are in the business of making money rather than health.
They rightfully aim to make the best-tasting food at the most cost-effective price, which means they won’t always focus on the highest-quality ingredients.
They will also use more fat and sugar (and salt) to enhance their flavors, which can add to unnecessary calories.
Eat at home as often as possible so that you can use the best ingredients, and know what’s going into your food.
Focus on colorful veggies, choosing primarily organic. Consider these lists from the EWG to see which vegetables are most important to buy organic.
For protein quality, buy organic, pasture-raised meats and poultry, and look for wild-caught fish. We’ll discuss this more next.
When buying sauces or dressings, avoid unnecessary added fats and sugars, especially high fructose corn syrup.
Get more tips in: Healthy Meal Prep: 8 Ways To Cook Your Way To Better Health (even if you’re busy).
Functional Nutrition Principle #3: Make Protein The Star Of Your Meals
How much protein do you need to optimize health and healing?
We generally recommend aiming for 1.1-1.6g of protein per kilogram of ideal body weight (or 0.7-0.8g per ideal body weight in pounds).
If you’re an athlete and/or trying to build muscle, your goal may look more like 1g per ideal body weight in pounds.
It’s best to spread this over at least 2-3 meals, which enhances satiety while preventing overeating.
Choose your favorite protein and make it the star of your meal (1/3-1/2 of your plate), and build around it with plenty of colorful vegetables and a healthy carb.
As discussed in: How Protein Optimizes Healing & How To Find The Best Sources, protein is essential for:
- Muscle building
- Cognitive function
- Overall metabolic health and blood sugar balance
- Structure
- Locomotion
- Hormonal function
- Detoxification
- Cellular health
- Immune function
- Fluid balance
- Neurotransmitters
- Recovery
Even sedentary people, who are at the highest risk for muscle loss, experience less muscle loss and better health/durability over time when their consumption of dietary protein (especially the amino acid leucine) is optimized.
Functional Nutrition Principle #4: Choose Leaner Cuts Of Protein
We want you to eat enough protein for sure, but we also want to ensure those protein sources are healthful.
Leaner cuts of animal-based protein have less fat, and therefore, they have fewer calories. This makes it easier to use these “saved, discretionary calories” more intentionally.
For example, if you are really active, the saved calories might be better used in the form of starchy carbohydrates, like potatoes or rice.
These calories could also be used as olive oil over your salad greens or as avocado oil to prepare roasted veggies.
Also, when you’re eating out or have less control over your protein sources (for animal proteins, we recommend organic or grass-fed/regeneratively raised), choosing leaner cuts of meat will also help limit toxins, which tend to be stored in animal fat.
Vegetarian/vegan sources of protein and protein powders are typically naturally lean, although we recommend being very selective about protein powders, soy, and fake meats.
See: How Protein Optimizes Healing & How To Find The Best Sources for tips and advice on finding clean plant and animal protein sources.
Functional Nutrition Principle #5: Eat The Food On Your Plate In This Order
This is such a simple hack, but it really helps ensure you’re promoting satiety and balanced blood sugar without overeating or skipping out on the most nutrient-dense foods.
Here’s the order we recommend:
- First, eat your protein because that’s what will fill you up.
- Second, while eating your protein get after those non-starchy vegetables, which provide ultra-rich in life-giving nutrients like vitamins, minerals, antioxidants, phytochemicals, and fiber.
- Third, enjoy your carbs and/or “fun carbs”, like dessert last. This slows their absorption which helps keep blood sugar regulated.
Avoid eating starchy carbohydrates alone as much as possible, as this can negatively impact blood sugar. It’s best to have starchy carbohydrates with protein.
Functional Nutrition Principle #6: Focus On Omega-3 Fatty Acids
You’ve likely heard of omega-3 fatty acids before, but here’s a deeper dive into these incredibly important healthy fats.
Omega-3s are essential fatty acids, meaning they must be consumed because your body can’t make them.3
The three main types of omega-3 fatty acids are:
- Alpha-linolenic acid (ALA),
- Eicosapentaenoic acid (EPA),
- And docosahexaenoic acid (DHA).
Every cell in your body (and you have about 37 trillion of them!) is lined in a membrane made of a phospholipid bilayer, which is medical speak for a phosphate head with two fatty acid tails.
This membrane acts as a semi-fluid barrier and houses all the receptors needed for communication and other proteins/channels that regulate what comes in and out of the cell.
Omega-3 fatty acids are essential for this membrane to function properly. They also play a role in blood clotting, arterial wall function, and inflammation.
Almost everyone should be conscious of consuming omega-3 fatty acids daily, no matter what dietary guidelines they follow.
The research on their beneficial effects on inflammation alone makes them worthy of a place on your plate.4
The most bioavailable forms of omega-3s are EPA and DHA, found most abundantly in fatty fish like salmon, mackerel, anchovies, sardines, and herring.
For fish sources high in omega-3s and low in heavy metals, like mercury, we recommend wild-caught and sustainably harvested:5
- Salmon
- Mackerel
- Anchovies
- Sardines
- Herring
Remember the acronym SMASH (Salmon, Mackerel, Anchovies, Sardines, Herring) when choosing clean, omega-3-rich fish and seafood.
Plant-based, precursors to omega-3s, called ALA, are found in walnuts, chia seeds, hemp seeds, flaxseeds, algaes, and evening primrose oil. These are good vegetarian or vegan sources for EPA and DHA.
However, research has shown their conversion is variable and sometimes limited (67). So, unless your religious or dietary principles dictate otherwise, it’s best to focus on consuming (or supplementing with) EPA and DHA.
Two of our favorite, pure and pharmaceutical-grade omega-3 supplements are:
Functional Nutrition Principle #7: Stay Hydrated
What we drink is just as important as what we eat.
We recommend drinking half your body weight in pounds in ounces of water throughout the day.
For example, if you weight 150 pounds, you’d aim for 75 ounces of water daily, not including any addition you need during exercise.
Drinking most of your water between meals is also best so you don’t dilute gastric juices.
Water purity is also very important these days.
Therefore, we highly recommend using a high-quality water filter that goes beyond simply reducing chlorine flavor and lead.
Some of our favorite water filter brands can be found on the Trusted Products page of our website.
Functional Nutrition Principle #8: Observe A Rest and Digest Period Versus Intermittent Fasting
Many functional medicine and health experts tout the benefits of intermittent fasting (going 13 hours or more without eating), which has merits in certain situations.
However, it can also heighten the stress response, and that can be too much for someone already dealing with chronic, high levels of stress or those with HPA axis dysregulation. This is especially true for women, as I find men tend to tolerate fasting better.
Emerging research also suggests that Intermittent Fasting may negatively impact hormonal circadian rhythms.8
It’s also very triggering for some people emotionally, especially those with trauma, a history of disordered eating, or anyone with body image issues.
More research is needed, but based on emerging evidence and our clinical experience, it appears this type of regular fasting may not be ideal for everyone.
So, if you’ve struggled with intermittent fasting and wondered why, it was likely your body telling you it is not the right strategy for you now.
Again, we do not ascribe to a one-size-fits-all approach here, even if it’s trending in the functional nutrition/medicine space.
Instead, we recommend what’s known as a 12-hour rest and digest period.
Here, you aim to pause eating for about 12 hours between dinner and breakfast.
This will support insulin sensitivity and optimize your migrating motor complex (which helps clean up food debris and bacteria from your gut). It will also allow cellular energy to focus on cellular repair, detoxification, and more.
Many people do this intuitively, eating their last meal around 6 PM or 7 PM and eating breakfast around 6 AM or 7 AM the next morning.
One of our favorite ways to encourage self-care is to recommend that our patients enjoy a substantial breakfast with around 30 grams of protein to optimize protein intake, which supports satiety and blood sugar balance.
What a refreshing idea vs. trying to get by until lunch on a cup of coffee with MCT oil or herbal tea and a tall glass of carrot juice(!).
Traditional medicine systems, such as Traditional Chinese Medicine, have also recommended daily periods of rest and digestion for thousands of years.
Are there exceptions? You bet.
If you’re waking up truly hungry or for no reason (especially between 2-4 AM), this can be due to low blood sugar (hypoglycemia) which illicits a spike of the stress hormone, cortisol.
If this sounds like you, I find people often benefit from a complex carb with some fat and protein closer to bedtime. Think: half an apple and almond butter.
You may also not be hitting your protein targets during the day, so listen to your body.
But generally, gifting your body a 12-hour rest and digest window is very beneficial.
Functional Nutrition Principle #9: Do Away With Boredom Eating
Okay, this isn’t just a functional nutrition principle but it is an essential one.
The truth is, we often eat when we just need a change in physical state.
If you know you do this (and take heart because most people do from time to time), come up with alternatives to snacking, like going for a walk, talking with a friend, or having a “Meditation Snack” instead of a food snack.
“Movement Snacks” are also great for changing your physical state.
For example, try doing ten squats, ten pushups, ten sit-ups or a ten-second plank, and ten jumping jacks for two rounds and see if it doesn’t satiate you in a new way.
You can also try:
- Drinking water with lemon or lime and even a bit of stevia if you need it.
- Do a cycle of 4-7-8 breathing.
- Splash water in your face (seriously).
- Walk your dog.
- Get some outdoor time.
It’s amazing how just pausing and engaging in another activity before mindlessly snacking can alter your physical, mental, and emotional hunger.
Also consider this: are you hungry because you haven’t properly fueled your body? If that’s the case, eat a good meal! Ignoring true hunger is not good for your physical, mental, or emotional health so make sure you’re eating enough.
Functional Nutrition Principle #10: Eat Gut-Supportive Foods Regularly
There’s a saying in functional medicine, “all disease begins in the gut.”
Therefore, functional nutritionist therapists focus on promoting foods that nourish, soothe, and diversify the gut microbiome.
Some of the best gut-friendly foods to include in your daily diet are:
- Plenty of non-starchy vegetables. These are a source of fiber that promotes regularity and, in some cases, feeds healthy gut microbes, gut-friendly nutrients, and those powerful anti-inflammatory antioxidants.
- Prebiotic-rich foods. Prebiotics are a type of fiber that resists digestion and ferments in the gut, where it becomes the primary food source of healthy gut bacteria known as probiotics. Excellent sources of prebiotics include:
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- Onion
- Garlic
- Asparagus
- Green bananas
- Cooked and cooled potatoes
- Cooked and cooled rice
- Sunchokes
- Artichokes
- Leeks
- Mushrooms
- Soybeans (but only organic and, ideally, fermented, please)
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- Probiotic-rich foods. These are your ferments, which contain naturally occurring probiotic cultures. Examples include:
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- Cultured vegetables
- Real pickles made with just salt and water or a natural starter
- Kombucha (low-sugar-only varieties, please!)
- Kimchi
- Yogurt (dairy or dairy-free, low or no sugar)
- Kefir (dairy or dairy-free, low or no sugar)
- Sauerkraut
-
-
-
-
- A note for those with digestive issues: if you find that prebiotics and probiotics trigger bloating and digestive symptoms, this is worth exploring further. Many of our patients with underlying gut infections don’t tolerate foods that are high histamine, or high FODMAP, for example. You can learn more about this in: How to Heal Your Gut 101.
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- Healthy fats. Healthy fats are essential to cell health and the production of specific gut bacteria, like butyrate. Our favorite healthy fats are the least processed and contain a more balanced ratio of essential fatty acids. These include:
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- Avocado oil
- Coconut oil
- Extra virgin olive oil
- Flaxseed oil
- Ghee
- Grass-fed butter (for those who can tolerate dairy)
- Small amounts of cold-ressed Hemp oil, Sesame, or Walnut for flavor
- Clean proteins. Research has shown that grass-fed beef, for example, is a good source of omega-3 fatty acids and other gut-friendly nutrients like butyrate. We also recommend some protein supplements specific for gut healing, such as collagen peptides and bone broths, which are wonderful sources of gut-soothing gelatin and glutamine.
Functional Nutrition Principle #11: Be Mindful Of Sugar Intake
We discuss this in detail in: Tips To Stop Sugar Cravings + A Guide To Healthy Natural Sweeteners, but here are the cliff notes.
Most processed and packaged foods, condiments, and beverages contain added sugars.
Processed sugar is no one’s friend and has been linked to: 9, 10 ,11 ,12, 13
- Accelerated aging
- Behavioral issues
- Dental issues
- Diabetes
- Fatty liver disease
- High blood pressure
- High cholesterol
- Immune function issues
- Insulin resistance
- Mental health issues, like depression and anxiety
- Metabolic syndrome
- Neurodegenerative disease
- Obesity/ Weight gain
- Polycystic ovarian syndrome (PCOS) and infertility
So, how much sugar should you aim for daily?
To be clear, humans can survive and thrive just fine without added sugar in their diets. Most of us get plenty of glucose from fruits, vegetables, and other healthy carbs.
However, we also believe in balance, which includes having something sweet now and then.
So, ideally, you’d aim for the following, making concessions for special occasions:
- Most women should consume no more than 25 grams or less than 6 teaspoons of added sugar daily.
- Most men should consume no more than 37.5 grams or less than 9 teaspoons daily.
- Children ages 4-8 with a daily caloric intake of 1,600 calories should consume no more than 12 grams or 3 teaspoons a day.
If you add some coconut sugar to your coffee in the mornings or enjoy a square or two of dark chocolate, you can easily stay in these ranges, provided you’re conscious of hidden added sugars in processed foods.
Functional Nutrition Principle #12: Forget Perfection And Instead Focus On An 80/20 – 90/10 Approach
Let’s face it. Extreme diets and nutritional approaches, such as those that eliminate entire food groups or employ the use of food fear or shaming, almost always fail because perfection is totally unrealistic and it’s unhealthy.
Heaven knows we (especially women) all need more grace and less self-shaming regarding food.
Yes, we must also take responsibility for our food choices and how they impact our health.
However, in our functional medicine practice, we recommend patients focus on an 80/20 – 90/10 approach to functional nutrition and get off the perfectionism train fast.
Why the variance?
It depends on what the individual is dealing with and their health needs and goals.
Some people can heal and do just fine, allowing 20% of their diet to be less than optimal, while others may have an autoimmune flare if they digress more than about 10% of the time.
There are also circumstances where we recommend aiming for closer to 100% compliance with certain foods, such as if a patient has celiac disease and cannot tolerate any gluten or during an elimination diet where sticking “to the letter” is essential to gather correct intel.
However, generally, the 80/20 rule gives enough wiggle room to make applying functional nutrition principles wildly successful while boosting self-esteem, enjoying food freedom, and getting the results you’re looking for.
Plus, all the women in our practice, including me, love food and believe it should be a source of enjoyment and celebration.
So, when you can’t make the best choices (or just really want a treat, an awesome date night, special time with loved ones, vacation, etc), be mindful of that 80/20 goal and relax into a deep appreciation of your food and the company you enjoy it with.
Summing It Up + How To Get Started
While there is no one-size-fits-all dietary pattern for all people, these functional nutrition principles can help move you closer to health and a healthier relationship with food.
There is really no need to commit or limit yourself to one diet or nutritional philosophy. Instead, use these commonsense principles to build a nutrition strategy that honors the ultimate principle of “food as medicine” while keeping eating fun, pleasureful, and interesting.
Where should you start with these 12 principles?
We suggest choosing one, two, or three that seem most doable, putting those into practice over the next couple of weeks, and then adding on from there.
When we work with new patients, we typically start with focusing on blood sugbalance, increasing protein, drinking enough water, and adding gut-friendly foods.
But choose what speaks to you and start there. Intuitive eating can be a real asset here.
If you want to learn what specific dietary patterns and foods would be most helpful for you, we suggest working with a functional medicine physician, nutritionist, or practitioner who can help you understand your genetics and current nutrient status and create a dietary lifestyle you can stick with.
If you’re in our tri-state area (Colorado, Michigan, or Texas), we’d love to help you one-on-one! Click here to learn more about becoming a patient and meet our team of functional medicine and nutrition experts.
Remember, it is what we do on a consistent basis that creates our health outcomes, which is why good nutrition is so important!
Functional nutrition can provide actionable principles anyone can apply to start deeply nourishing themselves and restoring optimal health.
Sources
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4586535/
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1868084/
- https://ods.od.nih.gov/factsheets/Omega3FattyAcids-Consumer/
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8846546/
- https://www.fda.gov/food/consumers/advice-about-eating-fish
- https://ajcn.nutrition.org/
- https://pubmed.ncbi.nlm.nih.gov/16188209/
- https://pubmed.ncbi.nlm.nih.gov/34474513/
- https://link.springer.com/referenceworkentry/10.1007/978-0-387-33754-8_112
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9471313/
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8643565/
- https://www.cdc.gov/pcd/issues/2021/20_0574.htm
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8198281/
