Nutrition Data: The Ultimate Guide to Personalized Nutrition
Why Do We Need Nutrition Data?
Rates of obesity are rising in every country on Earth. Much of the developed world has taken food for granted. Calories are now relatively easy to come by. And with it, a host of preventable chronic diseases including cardiovascular disease, type 2 diabetes, chronic kidney disease, many cancers, and an array of musculoskeletal disorders.
Furthermore, micronutrient deficiencies continue to be widespread. Globally, 2 billion people suffer from low micronutrient intake of one or more essential vitamins and minerals. Many of these are present in developing nations and are due to more systemic problems surrounding social, economic, and political issues. But low micronutrient intake is prevalent even in America, and certain groups are at a high risk for micronutrient deficiencies.
"Food, once our source of health, has become our biggest source of disease."
In order to get the world’s diet back on track, and to enable each and every one of us to reach peak health and performance, 3 processes could help.
Identify the diet and nutritional needs that uniquely fit your body and your mind,
Track and maintain these diets over the course of a lifetime, and
Monitor your health outcomes and adjust where needed.
Fortunately, new science is being discovered and new products and services are being developed to make the process of collecting personal nutrition data easier.
So what exactly is personalized nutrition? How can it help me? What products and services can I use from home to personalize my diet?
What Is Personalized Nutrition?
At its core, personalized nutrition is a diet designed to fit the physical, mental, and environmental needs of an individual.
Nutritional needs are much like people. We’re similar in many ways, but we also have differences in the way our bodies have developed and the lives we each live.
We have different preferences, different cultures, and different biochemical reactions to food.
Personalized nutrition applies this logic to nutrition.
Emotions and preferences are heavily wrapped up in our diets, and culture is a big part of the discussion. It may be a losing battle to ask Okinawans to give up rice or Sardinians to give up wine. And despite their different diets, these “Blue Zones” both have large populations that tend to live past 100 with relatively low rates of chronic diseases.
But we also can possess different biochemical reactions to food as well.
Allergies are a clear example. Roughly 3 million Americans have coeliac disease and cannot eat gluten, peanut allergies have more than tripled in U.S. children over the last few decades, and you can even develop an allergic reaction to meat through the spread of a virus from a tick bite.
But it goes far beyond these obvious constraints.
Differences in genetics can alter predispositions for certain health outcomes; one person may possess genetic qualities that predispose them to gaining weight more easily, while another may possess inefficient vitamin B12 metabolism.
And although these studies are too early to make definitive predictions, some research has shown that individuals possess certain genes that have better health outcomes on a high-carb, low-fat diet, while other genes suggest better outcomes on a low-carb, high-fat diet. Other genes have shown links to high blood pressure, appetite, and many other aspects of diet-related health outcomes.
The lives we lead also greatly impacts our biochemistry and metabolism, each affected by changes in things like stress, sleep, family eating dynamics, and diet itself. Differences in lifestyles and environmental conditions can alter epigenetic modifications to your genes and shift gut microbiota composition.
And these effects are likely not the same in everybody. A recent study in Cell showed a widely varying glycemic response between individuals to the same meals. In addition to clinical differences, like the amount of sleep they got the night before, their gut bacteria composition played a substantial role in their body’s response to food. And while your gut bacteria affects which foods you should eat, your food in turn affects your gut microbiome diversity.
Epigentics may play a role too. Epigenetics refers to modifications in gene expression. This means, certain lifestyle and environmental conditions may change which of your genes are promoted or inhibited.
Research is accumulating on the role epigenetics may play on nutritional health outcomes, particularly for environmental conditions in early-life. And although this was only a rat-study, an interesting finding showed obese rats produced epigenetic changes that resulted in decreased leptin, the hormone that makes you feel full. Epigenetics will be an interesting area of research to watch.
When it comes to weight loss, many diets of varying macronutrient composition have been tried. A recent review and meta-analysis showed they can all work to help lower weight. The biggest determinant was whether study participants could stick to the diet.
There are some broad commonalities. Protein may increase satiety and thus, make it easier for more people to consume fewer calories because they feel more full for longer. And carbohydrates, in general, tend to produce a higher glycemic response after meals.
But these studies in gut microbiome and gene expression are beginning to shed light on the reality that the magnitude of these effects can vary quite dramatically in different people.
Finding the Diet that Works Best for You
Personalized nutrition is the recognition that certain diets are individually better suited for certain people. This accounts for variability in personal preferences and dietary constraints, as well as biological variations in genetics, epigenetics, and gut microbiota.
Long-standing dietary advice from major health organizations still hold true. Listen to the expert opinions on major macro and micronutrient recommendations. Their advice will rarely lead one astray.
But often, achieving their targets and your own personal goals can be easier said than done. Personalizing and optimizing your diet using nutrition data to fit your unique biology and environmental conditions can help optimize and accelerate your progress to help you meet your goals.
Why Should I Optimize My Nutrition
Let’s start from the beginning. The first law of thermodynamics says:
Energy can neither be created nor destroyed.
There’s no getting around that one. But - it can be transformed.
Nutrition is our body’s fuel. We can’t live without it. But there’s a difference between living with optimal health, and just living. For example, The Michael Phelps Diet was 8,000 - 12,000 calories a day. He needed OLYMPIC-scale energy. He doesn’t just train like the normal weekend warrior. He needs to maintain peak energy throughout training as well as on race day.
Conversely, it’s easy to live on a poor diet for quite some time; all the while building a lifetime’s worth of poor dietary habits that lead to many of the chronic diseases facing us today.
Calories are directly defined as a unit of energy. Energy is locked up in the chemical bonds within food molecules.
I good way to think of the energy you consume is by the ratio of your macronutrients - fats, proteins, and carbohydrates. They all contain energy your body can use, but in different ways. We’ll dive deeper into that later.
During digestion, these molecules get oxidized. Essentially, vitamins, minerals, and other enzymes break these chemical bonds apart, releasing energy. That energy is generally repackaged into ATP - the body’s energy currency.
Unused energy typically gets stored for later, generally in the form of fat.
So, I’ll just track my calories, right?
Calories are important, yes. Those who track and reduce caloric intake routinely lose weight and improve cardiovascular health.
And yes, if you ingest more calories than you burn, over time, you will gain weight.
But the energy balance equation of calories in and calories out is riddled with personalization that complicates the math. Some examples:
Resting metabolism: Just sitting on the couch, we all burn calories at a different rate.
Gut Microbiota: Different diets and environmental conditions change your gut bacteria composition. For example, some people can extract more calories from fiber than others.
Genetics: Each person’s DNA is unique to them (except for twins!). And just like hair color, they can change the way your body reacts to food.
Macronutrient Composition: Your body reacts to them differently. For example, were your calories from protein or sugar?
Micronutrient Composition: Your age, gender, genetics, and lifestyle affect which vitamins and minerals you may be in need of.
This guide will dive deeper into where this personalization comes from, and how to go about collecting nutrition data to personalize your diet.
You Can't Improve What you Don't Measure
Optimization occurs along a particular dimension, so you must decide along which dimension you are looking to optimize.
Body-builders may be going for bulk, long-distance runners may need to ensure long-term fuel and adequate mineral ratios, and chess champions require their brain to be firing on all cylinders.
You may be looking to simply find a consistent diet you love that allows you to optimize long-term health and general wellbeing. Or perhaps you are looking to lose weight efficiently, adhere to a dietary regime like veganism. or are experimenting with something new like a ketogenic diet.
Whatever your goal may be, they all start with the same step.
To optimize your diet, you must routinely and reliably monitor your dietary intake patterns.
Optimization requires experimentation and refinement over time. And you can’t improve what you don’t measure.
Therefore, optimizers must first start with reliable nutrition data to provide a baseline for understanding how their body reacts and make evidenced-based decisions to adjust and track.
You might feel like you have a fairly routine and repetitive diet (I have a protein shake and two eggs every morning!). But few of us eat the same meals, in the same quantities, every day. And we certainly don’t have the same amount of physical activity, stress, or sleep everyday.
So when you are trying to remember your meals and compare content between your best performing day and your worst, ask yourself: “What was my macronutrient breakdown? Did the percentage of my calories coming from protein change? What about magnesium? Or potassium?”
Odds are, you won’t even have the same performance if you did isolate a top-performing diet. There are many factors that will influence peak performance, like sleep and stress.
But this is a numbers game. If you continue tracking and monitoring performance based on dietary intake, patterns will begin to emerge.
You first need to know how to quantify and categorize your dietary intake patterns. Only then can you intelligently adjust, monitor, and optimize based on your performance.
There are several different aspects of your nutritional health and eating habits that can be tracked to personalize your nutrition. Some are immediately available, while others are in the works. And some require only a one-time test, while others are ongoing.
As new science continues to improve our understanding of nutritional health, new products and services continue to crop up.
This list is designed to be a comprehensive guide to at-home nutrition personalization services available, and several that are coming soon and are in the pipeline.
A couple of notes before we get started:
Intake is not affiliated with the products or brands in this list.
Nutrition science is notoriously convoluted. We attempt to provide a mix of the scientific consensus and emerging, yet promising, science.
In areas where nutrition data science is less well-defined, we do our best to explain our current understanding, the potential it may bring to personalized nutrition, and our approach we recommend to new products and services that aim to use this data.
Body Mass Index (BMI) is a common measurement used across the diet world. Simply put, your BMI is related to your weight to height ratio. So, the more you weigh for your given height, the higher the ratio.
This is a useful, quick measurement for determining if someone is underweight, in a healthy range, overweight, or obese.
However, this doesn’t quite capture the whole story.
As you can imagine, muscle plays a much different role on your health and the way your body metabolizes food than fat.
And taking it one step further, not even all fat should be treated the same way. Studies show that visceral fat is worse for disease risk factors like cardiovascular disease and diabetes than subcutaneous fat or brown fat.
This distribution of fat within the body can produce some counterintuitive health outcomes. For example, roughly 10% of obese individuals show no signs cardiometabolic risk factors; conversely, 10% of normal weight individuals (18 < BMI < 25) possess a body fat distribution similar to that of obese individuals. These so-called TOFIs (Thin on the outside, fat on the inside) are at high risk for developing metabolic diseases like diabetes because the location of fat is important.
In fact, this distribution of body fat may be the cause of the so-called “overweight paradox,” where some studies have shown a similar risk of cardiovascular disease-related morbidity and mortality to that of normal weight individuals in the elderly.
So how do you know what your body fat composition is?
Bioimpedance spectroscopy can be used as an in-home method of decomposing body-fat percentage. A quick Google or Amazon search will bring up quite of few of these devices from different brands, usually sold as a scale or handheld device.
These work by sending a small electrical current (too small to notice) of varying frequencies through your body and measuring the voltage. Different body tissues (i.e. fat, muscle, bone, etc.) change the voltage by different amounts. Using some clever algorithms, these device then determine the breakdown of your body composition.
Are they accurate?
Accurate? Not so much. Precise? Somewhat. But they are getting better.
Like most biochemical testing procedures, it is recommended to practice consistency between measurements. Try performing the test at the same time every morning (exercise affects the test results) and after using the restroom (hydration levels affect this test too).
The technology is improving, but studies in obese patients and in children continue to show statistically significant errors when compared to gold standard measurement techniques like dual x-ray absorptiometry.
They can be useful for group analysis, but individually the accuracy is not quite good enough. This goes for body fat distribution measurements, as some devices purport, as well.
Are they still useful?
Despite some error, they can be somewhat useful for qualitative analysis. Providing a rough estimate, and monitoring change over time, may provide useful ballpark figures for trends.
Your body fat percentage, fat mass, and fat-free mass are important for health implications, as well as understanding how your body is metabolizing energy (we will go into more detail on this later).
Being overweight or obese increases your risk of several chronic diseases, including type 2 diabetes, cardiovascular disease, and some cancers. However, body composition does impact the magnitude of that risk, and it can put normal weight individuals into high risk categories.
In the pipeline
Improvements to bioimpedance analysis hardware and algorithms may continue to refine the sensing techniques for determining body fat composition and fat distribution. Until then, home-based tracking is relegated to waist-to-hip ratios and inaccurate bioimpedance scales.
While medical labs and nutrition facilities often have equipment to help you determine these numbers, home-tests for body fat distribution are still in the works.
Blood, Sweat, & Tears
There is a small but growing group of healthy individuals who wear continuous blood glucose monitors to quantify their body’s response to food. These small patches have tiny needles that detect blood glucose and transmit the readings to your smartphone.
After a meal, metabolism begins harvesting energy from the food you ate. This results in a rise in the amount of glucose circulating in your blood (blood glucose). This is called the glycemic response.
Some food groups cause a sharp spike in blood glucose. Sugar is a prime example.
Other foods, often high in fiber, cause a much smaller and gradual rise in blood glucose.
Any rise in blood glucose levels cause a rise in the release of a hormone called insulin. Too much glucose in your blood will cause you some serious problems. One of insulin’s jobs is to regulate glucose levels by decreasing its concentration in circulation.
It is interesting to track the behavior of your blood glucose response to foods for a few reasons. First, is to spot and monitor pre-diabetes so as to manage and possibly reverse the disease early.
Chronic hyperglycemia (high blood glucose levels) is a sign of pre-diabetes and diabetes. Chronic hyperglycemia is also associated with many of the ill-effects of diabetes, including injury to the heart, nervous tissue, retinas, and kidneys. Monitoring blood glucose levels can help spot and diagnose pre-diabetes with enough time to potentially halt and reverse the disease, as well as for maintenance of symptoms for sufferers of the disease.
Second, it can also be useful to track your blood glucose response to foods to better understand the unique way your body responds to food. A recent article in Cell showed that the glycemic response can vary significantly between individuals, despite eating the same types and quantities of foods. This may eventually help you gain insight into the health of your gut microbiome (which we will discuss more later) and better personalize your diet.
Micros have a Macro Impact
Another major component of your diet that can be partially interrogated via blood testing is your micronutrient levels.
Micronutrients consist of vitamins and minerals. They are essential for life, being used in numerous biochemical pathways as catalysts and coenzymes.
Deficiencies in any one of these can cause both acute problems (when the deficiency is severe), and chronic (when persistent undernutrition occurs). Unfortunately, micronutrient intake in modern diets is routinely too low.
So while your body can handle short term deficiencies, long-term deficiencies should be avoided. Invasive blood testing is one option for determining recent micronutrient intake levels.
SpectraCell is one of the leading blood-testing service providers for micronutrient testing services. A few others, like WellnessFX and LifeExtension, also perform these tests.
However, an at-home product that draws and analyzes blood requires FDA approval and isn’t yet on the market; although a few seem to be in the works (in the pipeline, below).
The next best thing comes from ZRT Labs, which provides at-home kits that are mailed back to a central lab for analysis. ZRT provides dried blood spot tests with a finger-pricking tool to draw blood and mail away. One prime example is to look for vitamin D deficiencies.
Additionally, ZRT has saliva kits. Although looking for different biomarkers, these tests primarily look for hormones that reveal information such as thyroid function.
Other companies like Meridian Valley Labs also provide home blood kits that test for hormones, but they also assess food allergies which can be extremely useful for identifying the source of major food reactions.
In the pipeline
A few companies working on at-home blood testing devices for nutrition-specific biomarkers include Vitameter and KalibrateV. These aren’t yet on the market, and it’s not yet sure if they’ll make it. But be on the lookout for these and others. They will surely start to crop up soon.
The Kenzen patch is a new product used to monitor hydration levels and electrolyte imbalances. This may be useful during training, where making sure hydration stays at the top of mind. Ultra-endurance athletes may find this particular appealing. Kenzen also suggests their product can be used to assess electrolyte imbalances.
X labs (Google) made a bit a press when they were working on a contact lens containing microelectronics designed to measured glucose from tears. But as the CEO of Novartis, a partner on the project, says, “It’s a high risk project.” Many researchers claim the correlation of glucose in tears is not as robust as blood, and therefore will never provide clinically useful information for diabetic patients. We’ll have to wait and see about this one. It will likely be years before a product like this demonstrates any breakthroughs.
Saliva is an enticing biological medium because it is non-invasive and easily acquired. And while some markers of diet and nutrition can be discovered in saliva, its reach is limited.
One interesting area might be related to teeth health. Diet has a profound impact on tooth and jaw development. Foods like sugar and starch are known to cause cavities and other problems with teeth. But saliva may provide insight into the current health of your teeth and the amount of resident bacteria.
But since your DNA is the same in every cell of your body, saliva does provide an easy access point for genetic testing.
Fitting Into Your Genes
DNA testing is an exciting, emerging field brought on by the dramatic reduction in DNA sequencing costs. The Human Genome Project took 15 years and $2.7 billion to sequence the first human genome in the year 2000. Now, we are close to a $100 genome sequencer that will only take a an hour! And it will only continue to fall in the future.
Sequencing your DNA has myriad medical uses, especially with new gene-editing techniques like CRISPR. There are other interesting uses too, like tracking your ancestral line using services like 23andMe and Ancestry.com. But for now, we’ll focus on how they relate to your diet and nutritional health.
Your DNA is unique to you. It is present in all of your cells, and it contains the information needed to make you you. It directs everything from how to build your hip bone when you were in the womb, to how your body is going to treat gluten once it enters your digestive system.
Genes are sequences of DNA that decide how your body is going to produce different proteins. These proteins then go off to do all of the different things they do to make life happen.
Sometimes mutations occurs. If a mutation within a gene occurs, that may change the ability of that gene to produce its corresponding protein. And since these proteins go off to make life happen, you have a chance of experiencing life differently if those same proteins are produced in different ways or different amounts.
Often genes work together through a cascade of biological processes to get work done. In these cases, genetic mutations must be thought of as changing probabilities.
And example is the BRCA1 gene. Mutations in these genes are associated with an increased risk of developing breast cancer. But they demonstrate how they should be dealt with when thinking about probabilities.
Having a mutation in the BRCA1 gene, for example, does not change your risk of developing breast cancer from 0% to 100%. But, it can still be significant. A typical American woman has a 12 percent chance of developing breast cancer in her lifetime. But a woman with a BRCA1 mutation has a 55 to 65 percent chance of developing breast cancer.
Not insignificant, by any means. But also not certain.
These are population-wide statistics, and other contributing factors are required for the disease to actually develop. Many are unknown, often requiring some combination of environmental factors, lifestyle choices, triggers, and pure chance.
The same logic applies to most dietary intake needs.
For example, the FTO gene correlates to a propensity for obesity, and the CYP1A2 gene correlates with your ability to metabolize caffeine. But it’s important to keep in mind, that it’s believed that well over 40 genes correlate to obesity; and the genetic loci discovered to have associations with obesity are only shown to account for about 2-3% of obesity risk. So analysis and recommendations based on the presence or absence of genetic markers should be viewed cautiously, and sometimes modestly.
But, predispositions can help you personalize your diet in very real ways. Many issues like obesity or cardiovascular disease are issues that accumulate through small differences incurred over a lifetime. And 3% can add up over time.
Knowing your predispositions, then, does not dictate your fate. This is usually some combination of genetics, your environment, some trigger, and chance.
Some genes, on the other hand, have what is called high penetrance. Unlike the predispositions mentioned above, mutations in these genes do have close to a 0-to-1 effect.
The LCT gene, for example, produces an enzyme called lactase. Some mutations to the LCT gene are known to produce lactose persistence in practically everyone with that mutation, while other mutations can render your chances of being able to tolerate lactose at 86 to 98 percent. This gene, in other words, has high penetrance towards lactose intolerance.
Lactose intolerance often develops as we age out of the weaning process. This is an interesting example of a relatively modern form of human evolution based on a cultural shift to an agrarian lifestyle with livestock milk and shorter weaning periods.
Can my genes change?
Your DNA doesn’t change (with the exception of mutations).
But, the way your DNA is expressed can change.
Your DNA carries information about how to build proteins, and it is the exact same DNA in every cell of your body. That means, your hair cell, your muscle cell, and your liver cell all have the same DNA.
But your hair cells and liver cells behave quite differently. This is because they are expressed differently.
Some genes are turned on, while others are turned off. One cell uses part of your DNA, while another cell uses a different part.
This change in expression can indeed change based on lifestyle and environmental factors. Even more odd, is that these changes to DNA expression sometimes can be passed down through generations. This is the field of epigenetics.
Genetics refers to the sequences of DNA that are heritable (they pass from one generation to the next). But epigenetic changes may be heritable too. The mechanism for epigenetic inheritance is still not well understood, but it may provide some interesting insights into how diet and exercise can change gene expression.
For example, a recent study published in Cell Metabolism showed that the epigenetic profile of sperm in obese and lean men were markedly different, particularly among genes known to be associated with obesity like FTO.
What does this mean? Poor weight management decisions don’t just affect your own health. You may be setting your children up for uphill battle.
One classic epidemiological example of this is the “Hunger Winter.” Children born during the Dutch famine of 1945 resulted in higher rates of diabetes and obesity later in life; and potentially even resulted in similar trends in their children.
The good news about epigenetics, is that the changes to DNA expression do appear to be reversible. So, if you stop smoking, begin exercising, and change your diet, epigenetic modifications may shift to a more favorable profile.
Your Personal Meal Plan
Your genetic (and potentially in the future, epigenetic) profile can help you produce a unique, personalized food plan that caters to you. Learning about certain predispositions may also help you justify certain lifestyle choices.
We should all eat nutritious foods. But if you discovered you are predisposed to developing insulin resistance from over-consumption of starches, you just might be more inclined to adjust your eating habits to help ward off diabetes.
How do I use this nutrition data to personalize my diet?
One inherent downside to genetic testing, is that the ongoing tracking and monitoring of diet and behavior isn’t possible. Your DNA doesn’t change.
DNAFit, Nutrigenomix, Anabolic Genes, Orig3n, and Fitness Genes are examples of popular solutions for using your DNA to help guide your diet and exercise regimes. With a quick saliva swab, your DNA gets sequences and particular genes known to be associated with particular dietary concerns like lactose intolerance and carbohydrate sensitivity are identified.
Others, like Habit, use a combination of DNA testing and a series of blood tests in order to provide personalized meal plans.
Information about these genes present in your DNA help you determine the likelihood of expressing each particular trait.
How would you use this?
Think of these results like a personal guide. These results can help steer your dietary needs in a direction that may prove to be a better fit for you body and help you optimize your health and performance.
Are there any home epigentic testing services?
Not yet. The closest is likely episona’s home sperm testing kit for measuring male fertility.
But diet is likely a factor that shapes your epigenome. However, it may be some time before enough science has been collected to use epigenetic profiling for personalized nutrition.
In the pipeline
Genetics is uncovering relationships our genes have with diet and nutrition, but so far their effects tend to be rather small with low penetrance. Take any guidance with caution.
But this is a rapidly changing field of research with new science sure to come in droves. Take new studies with a grain of salt, and wait for convergence among the experts before you try any major changes.
And be on the lookout for the first epigenetic testing services. They may crop up soon. But the advice on skepticism goes doubly for epigenetic tests. The field is sure to bring more understanding to personalized nutrition data, but it is extremely nascent. Give this one another decade.
According to Mitchell (1962),
Your basal metabolic rate (BMR) is simply “the minimal rate of energy expenditure compatible with life.”
When you run, jump, swim, and talk, energy is used. This isn’t too hard to conceptualize. But sometimes we forget about the other work going on behind the scenes. The work to keep you alive.
Beating hearts. Breathing Lungs. Thinking Brains.
Your body is constantly using energy simply to keep organs functioning and to keep you alive. This minimum amount of energy required to keep those internal organs functioning is your BMR.
In fact, roughly 70% of your caloric intake is used for this basal cost of living. According to an FAO review, your total metabolic breakdown roughly follows:
Skeletal Muscle 18%
Other Organs 19%
And because 10% of caloric intake is used for thermogenesis (keeping our bodies warm), only around 20% of our calories are used for the physical activities we pursue throughout the day.
Is my BMR unique?
There is a decent amount of variation among the population with respect to BMR. So what’s causing this variance?
This is an area of ongoing research, but there are some studies that suggest where this variance comes from. Largely, it comes from your body composition.
A 2005 study in the American Journal of Clinical Nutrition investigated potential sources for this variance. Here’s a snapshot of their findings:
63% of BMR variance came from fat free mass
6% came from fat mass
2% came from age
2% came from intra-subject variability and analytical error
26% was unknown
What characteristics were not associated with BMR variance?
Bone Mineral Content
The researchers also investigated the effect of three hormones on this variance, and found no significant variance associated with leptin or triiodothyrionine; but thyroxine seemed to account for roughly 25% of the unknown variance in men, but not women.
This leaves us with two major takeaways:
Your body composition is the major player in your basal metabolic rate; however
Roughly a quarter of the variance is due to "other," unaccounted factors.
Another 2009 study estimated that body composition accounts for roughly 80% of BMR. What’s causing the 20-25% of variance?
There are a few hypotheses. One, as noted in each study, is that the different tissue components of fat free mass are not accounted for. Studies show that resting energy expenditure can vary quite significantly between organs, tissues within organs, and organs between individuals. The size of organs vary, and the composition of organs can vary.
Other variations may compound as well. The brain uses slightly different amounts of energy during neural activity like visual stimulations, and temperature, stress, and sleep are all known to alter BMR.
And certainly, genetic variations may play a role as well. As we inevitably uncover more information about the genes involved with regulating different organ, tissue, hormonal, and cellular metabolic pathways, we will likely discover more insight into subtleties of BMR variance.
How is BMR measured?
The test for BMR is actually quite simple. Monitor your breathe; specifically, measure how much oxygen goes in and how much carbon dioxide comes out.
What does this test tell you?
Amazingly, this ratio (of carbon dioxide output over oxygen intake) explains where your body’s energy is coming from. A ratio of around 0.7? Mostly fat. 1.0? Carbohydrates. A balanced, modern diet is often around 0.8.
This works because of the chemistry of energy expenditure.
All carbohydrates have the same ratio of hydrogen to carbon atoms: 2 to 1. Because this is the same as water, 6 carbon dioxide molecules are produced for every 6 oxygen molecules.
C6H12O6 + 6 O2 → 6 CO2 + 6 H2O
This gives you 38 ATP molecules (energy) and a respiratory quotient (R.Q.) of 1.0.
Fat gives you roughly 16 carbon dioxides for every 23 oxygens (R.Q of ~0.7), and proteins give you around 63 carbon dioxides for every 77 oxygens (R.Q. of ~0.82).
The test itself requires some prep on your part. BMR is greatly affected by digestion (through food-induced thermogenesis) and muscle activity. So typically, you are not allowed to eat before the test (usually a 12 hour fast) or work out. And during the test, you are required to remain still to get to your baseline, resting state.
Then, you strap on a facemask or another mechanism so machines can collect and measure the exchange of gases into and out of your lungs.
A few handheld indirect calorimeters are available for home use. These operate similarly as a breathalyzer. After breathing into the device, out pops a rate of calorie burn.
One is the MedGem by Microlife. While simple and relatively inexpensive, the MedGem only tracks O2. By not also tracking CO2, it misses the complete picture.
As mentioned above, the respiratory quotient varies person to person based variables like body mass, age, gender, and others. The MedGem approximates the R.Q. as 0.85 for everyone. This can result in a decent amount of error.
However, it still provides a decent snapshot of your BMR and can help you refine your diet based on your metabolism.
Another option for a home-use indirect calorimeter is offered by Breezing. Although more expensive, the Breezing monitor does take both O2 and CO2 measurements using disposable biosensors and has been shown to be equivalent to clinical lab-scale tests.
Can I Change my BMR?
First, your BMR will give you a guide as to your minimum caloric needs. The average is typically around 1,500 kcal per day.
This can, and does, shift. Albeit, minimally.
Prolonged undernutrition will typically lower your BMR. This is one of the factors for why dieters often gain weight back once the diet is over, and why other dieters seem to “plateau” while trying to lose weight.
Your body does this in an attempt to self-regulate energy balance. Imagine yourself as a hunter-gatherer several thousand years ago. When food was hard to come by, it was useful for your body to slow down metabolism so you didn’t starve as quickly. Your caloric intake decreased, so you body’s energy demands decreased along with it.
Similarly, when your fat stores are increased during prolonged overconsumption, your BMR will increase by a small amount.
And the majority of your BMR is dictated by your fat free mass. Hitting the gym and gaining muscle mass, therefore, will increase your BMR.
Moving requires energy. That means, the more you move, the more calories you burn.
But there are some subtleties here worth noting.
Moving might not impact calorie burn as much as you think; and
Physical activity changes other diet and nutrition-related physiology “under the hood”
Here’s an example to put things in perspective. Although this depends on many factors, such as weight, an average person burns about 100 calories for every mile they jog.
Let’s think about that. If you run 10 miles a week, you will burn an extra 1,000 calories. On a 2,000 calorie per day diet, that’s only about 7% of your weekly calorie budget.
Then, you must contend with hunger. Exercise releases cortisol. Among other things, this hormone tends to stimulate appetite.
Is exercise worth it, then?
In addition to burned calories, exercise still works wonders for things like cardiovascular health, mental health, stress reduction, bone health, lean-muscle development, and so on.
And as we’ve discussed, lean muscle development will increase your BMR.
Calories for Calories
Diet induced thermogenesis occurs after you eat food. Any food.
Your body requires the use of calories - aka energy - in order to digest and use calories. You read that right. It may sound odd, but digestion is work for the body. So some calories are still required in order to digest food.
Macronutrients require different amounts of calories in order to be digested. Proteins increase thermogenesis the most (30% of calories burned), followed by carbohydrates (5-10%), and then fats (0-3%). A typical, balanced diet usually renders thermogenesis at around 10% of your total calories burned throughout the day.
The Obvious One - Moving Requires Energy
The final part of the equation here is how many calories you burn per day from your daily activities.
Do you move around a lot? Do you exercise?
Or do you sit in your car, take the elevator to your office, sit for 10 hours, head home to the couch, watch tv, and fall asleep?
In addition to your BMR (on average around 1,500 kcal/day), you may burn anywhere from 500 if you’re an office worker or another 5,000 if you’re training for a marathon.
To bring the discussion full circle, we’ll use your goals and a simple equation to help give you a guide to how many calories you should eat every day.
When you take in less energy than you expend, you will burn adipose tissue (fat, plus about 10% water per cell) for energy and lose weight. It won’t be much, but like saving for retirement, this will accumulate over time.
But keep in mind, how much you expend will change. As we’ve seen, your BMR will change as you consistently eat fewer calories than you expend and as your body composition changes. So maintaining consistency will require your food intake levels to change over time as well.
Gaining weight? A similar approach exists. But again, adding muscle weight or fat weight will affect your BMR in different ways.
Maintaining weight? Simply do your best to maintain energy balance. Like we’ve seen, your body has some incredible homeostatic mechanisms in place designed to help regulate your body during brief fluctuations. It’s a consistent over- or undernutrition that will slowly accumulate over time. But don’t worry. The process can always run in reverse!
In the pipeline
Breath can be used for identifying your BMR, but can it be used for other diet-related tracking purposes?
A limiting factor of all biological medium is the library of physiological biomarkers available. For example, if your breath doesn’t contain any molecules that relate to how much vitamin B12 you’ve recently consumed, no new technology will be able to “track” it.
But new research continues to expand what nutrition data is possible to track using breathe.
In the meantime, advances in breath analysis may be limited to better BMR-testing devices.
Flushing Data Down the Drain
The first thought that comes time when you hear “urine test” is likely the home pregnancy test.
These tests typically use a technology known as a lateral flow assay. Here, capillary forces pull urine up a paper strip. You can try this experiment at home. Take some paper, carefully dip it in water, and watch the moisture creep upwards.
Urine is non-invasive and is an end product of the digestion process. This means it is directly affected by your diet.
Urine is also a very complex mixture, containing a slew of small organic and inorganic molecules that come from upstream metabolic processes.
In lateral flow assays, molecular probes are places on the strip that find one of these particular molecules of interest in urine, and bind to it. They only bind to that a single molecule, and do something special when they do find their binding pair.
They change color.
The color change indicates the presence of the molecule, and there you go.
There are other urine tests, like pH test strips, or strips that look for ketone bodies. These work using a similar principle.
Hydration levels can be measured via urine pH. Many vendors sell disposable pH strips that can be easily used by dipping into a pure urine sample. After waiting around 15 seconds, the strip changes color and can be compared against a color guide to provide an estimate of pH.
Ketone test strips are available from a variety of