Basic Principles of Nutrition for Active People: Facts vs Fads

I am not a doctor or a professional in medicine or nutrition. This is not intended to be taken as medical advice. I am a fitness aficionado and my interest in nutrition has led to much reading and studying in this topic. If you are seeking medical or professional advice, speak to a physician or dietitian who can better assist you.

As a triathlete (4-time Ironman finisher, 70.3 and Olympic distance podium finisher, and a lifelong endurance athlete), some of this information is geared towards endurance athletes. However, most of the content is useful for anyone looking to invest in their health and live an active lifestyle.

In this piece I will try to explain the basic principles of nutrition at a high level. This information is sufficient to give you confidence when making nutrition decisions that may affect your wellbeing and performance. This will be a short read that will help you understand basic concepts and give you the tools to understand more in-depth articles, podcasts and books.

Learn to evaluate the quality of sources of information.

This is a key concept to understanding nutrition. Nutrition is a highly debated and popular topic, with many private interests acting as sources of information. It is difficult to sort through the endless articles, social media posts, influencer content, podcasts, etc. to differentiate the truth from the myths.

The first step is to understand the source of the information and to decipher if this source can benefit or profit from the information. Always be skeptical of the information source when it comes to nutrition, as it is a highly commercialized industry, and many claims are anecdotal or have low levels of evidence.

Look for sources that cite scientific studies. The terms to look for here are the following (from highest level of scientific consensus to lowest): Systematic reviews & Meta-Analysis of RCTs, Randomized control trials (RCTs), Observational research, Peer review editorials or articles, expert opinions. Additionally, Government websites tend to have reliable, scientifically proven data.

There are 3 citing formats which typically include the names of the researchers, the name of the study and the year of the study.

An example of one is: (Meagher, Barry, Lawson, Rokach, & FitzGerald, 2001). Facts are typically cited directly after the scientific claim is mentioned and can also be at the bottom of the article.

Be highly skeptical of anything that sources anecdotal evidence and tradition. Most of these sources of information come in the form of non-peer-reviewed media such as social media, podcasts by non-experts, websites selling products or services, product magazines, etc. It is important to note that just because something works for someone that does not mean that it will work for you. Anecdotal results from peers or online can be extremely unreliable.

Energy in


In this section I will break down each macronutrient into its own section. It is important to understand that a healthy and balanced diet is foundational for a healthy body and mind. Each gram of protein and carbohydrate contains 4 calories while 1 gram of fat contains 9 calories. The recommended dietary intake breakdown for macronutrients is 45%-65% carbohydrate, 15%-25% protein and 20%-35% fat. The intake can be adjusted within those ranges based on individual goals and needs based on physical activity. If you are an endurance athlete training for an Ironman or a marathon, you will want to be on the higher end of the range of carbohydrates. Replenishing the glycogen stores in your muscles and liver to properly fuel your body for long training sessions is a key factor in your diet for athletic performance.

On the flipside, if you are seeking to increase muscle mass and decrease body fat you may try increasing protein consumption to the top of this range as protein has a higher thermic effect of feeding, staves off hunger and can help increase lean body mass which has shown to increase resting metabolic rate.

There are many fad diets that aim at lowering or increasing only one macronutrient and giving importance to one above the other two. While different diets work for different people and different lifestyles, one should understand the importance of each of these macronutrients before deciding to try any diet. With this knowledge you can make educated decisions about your health. A balanced diet that gives importance to all macronutrients is also beneficial in achieving the recommended needs of micronutrients (vitamins and minerals) that our bodies need.

If you are considering any diet that suggest to drastically deviate from the recommended dietary intake ranges, look for scientific research that supports the claims and results. Do not rely on anecdotal evidence from supporters of this diet and keep in mind that most of these diets are restrictive diets, for this reason many of them tend to show great results in the beginning. A restrictive diet cuts out much of what can be consumed, and most fad diets cut out junk food, food high in trans fats and sugars. This leads to quick results of fat loss or change in body composition, but the long-term side effects of diets don’t always show immediate signs of their negative impact. Most individuals engaging in these diets are not getting lab (blood) work regularly to track the effects the diet is having on their health.

If you restrict the same junk food, trans fats and sugar but continue to eat a balanced diet and follow the recommended proportions you will likely see the same positive results. Consult a nutritionist of health care professional before engaging in any of these restrictive diets.


Protein molecules play a key role in many body functions throughout the body, including acid-base balance (balancing the equilibrium between acidic and alkaline molecules), energy production, cell signaling, and nutrient transportation.

Proteins in the human body are made up of 20 amino acids. These amino acids are made up of essential amino acids (EAA), conditionally essential amino acids, and nonessential amino acids.

Essential amino acids’ name reflects their importance for essential bodily function; however, they are not synthesized by the body. This means that we must consume them in our diet.

Conditionally essential and nonessential amino acids are synthesized in the body from other amino acids; therefore, they are not required to be consumed in our diet.

EAA (9) include three branched chain amino acids (BCAA), which are typically the ones that most of us are aware of. These are leucine, isoleucine, and valine. BCAAs are abundant in skeletal muscle tissue and therefore are very popular in sports supplements.

The list of all EAA is here: Histidine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, (BCAA) Isoleucine, Leucine, Valine. Look for these when shopping and comparing sports supplements.

The recommended dietary allowance for protein in the US is from 0.8–2.0 grams of protein per kilogram of body weight depending on range and levels of physical activity. Each kilogram is 2.2 Lbs. So, a simple equation for a person who weighs 175lb, looks like: 175 Lbs / 2.2 X 1.2 grams = which is roughly 95.5 grams of protein.

This protein requirement fluctuates as activity levels increase. 0.8 grams of protein is required for someone with no real levels of physical activity. As cardiovascular and strength training increase from moderate to vigorous levels, the protein needs can range from 1.2 to 2.2g/kg of body weight.

For most of you reading this article, 0.8 g/kg will fall short of your actual need. Based on your daily level of activity you should aim for 1.2g -1.8 g/kg, unless you are participating in high levels of cardiovascular or strength training. Endurance and strength athletes require between 1.5–2.2 g/kg, with more g/kg being required for vigorous levels of strength training. Anything above that is adding calories to your diet with little to no benefit.

As a triathlete training at high intensity levels, I try to aim for 1.8–2.0 g/kg, and I may increase that slightly on longer sessions lasting more than 3 hours, especially if these include intervals or reps at high levels of intensity.

Protein quality is often overlooked and is an important aspect of our consumption. This refers to the number of essential amino acids contained in protein and the digestibility of the protein.

A complete protein is a protein source containing all EAAs in their appropriate quantities, generally animal proteins are complete proteins and plant proteins are incomplete proteins (with soy being the exception) making it a great option for vegans and vegetarians. The digestibility of protein refers to how well the body can use the protein in the food source. Not 100% of the protein in any food source are digestible, with the highest-ranking protein being eggs at 98% digestibility. Therefore, if you consume 10 g of protein from eggs, your body can only use 9.8 g of this protein. The protein digestibility-corrected amino acid score was created for this reason and can be a useful source for assessing different sources of protein.

For those consuming most of their protein from plant sources — I am talking to my vegan and vegetarian friends, it is important to try to consume complementary proteins. This means finding mixed sources of protein that complement each other to consume all EAAs. For example, combining rice and beans. Their EAA profile is complimentary because rice proteins are poor sources of lysine, while beans are high in lysine but low in methionine and cysteine, which are plentiful in rice. Other examples of complimentary proteins are wheat and peanut butter, pasta and peas, hummus and pitta bread. A simple google of complimentary proteins can help you further understand this concept. It is not necessary to consume complimentary proteins during every meal but recommended on a daily basis. In other words, what you lack for your breakfast you can make up with your dinner.

A special consideration should be given to leucine because leucine acts as a signal to enhance protein synthesis and facilitate muscle recovery and growth. Leucine is the only EAA that has this ability, although all amino acids are necessary to form protein.

Research has shown that 0.05 grams of leucine per kg of body weight is an ideal consumption per meal to increase muscle protein synthesis.

Timing of protein consumption has been a hot topic in the sport community for a long time. Research has shown the protein synthesis threshold is 20 grams of protein, meaning that less than 20 grams of protein is not enough to stimulate protein synthesis. This is of importance to active people participating in regular levels of cardiovascular or strength training. If you are one of those people, it is ideal to cross this threshold more frequently in order to enhance protein synthesis numerous times each day. Therefore, eating 3 meals with each containing 20 grams of protein is more beneficial than 6 meals with 10 grams of protein or 1 meal with 60 grams of protein, even though the amount of protein consumed remained constant.

For my fellow endurance athletes there is a ratio that is often overlooked and underemphasized when talking about protein consumption. Post workout carbohydrate to protein consumption should be 3:1 or 4:1 carbs:protein. I will cover more on this topic in the carbohydrates section. This is especially important after long training sessions in which the same muscle groups are being utilized, such as long runs or bike rides. Contrary to popular culture messaging, post workout protein consumption for the purpose of increasing muscle mass and muscle recovery is less important than carbohydrate consumption due to the glycogen depleted state of muscles after exercise. Studies show more importance to total daily protein consumption than consumption of protein post workout, with little to no increase in muscle growth from consumption post workout as long as total protein consumption remained constant.


Carbohydrates have been getting a bad rep, so it is important to understand their function and importance to our bodies. There is much confusion and misconception regarding carbs. Part of the reason is the lack of understanding between simple sugars and complex carbs. Not all carbs are made up of processed carbs such as bread, pasta, white rice, etc. Carbs are also made up of fruits and vegetables, these are complex carbs are packed with vitamins and nutrients. Simple carbs are sometimes referred to as “empty calories” because they do not provide many additional vitamins and nutrients which make them less effective at staving off hunger and quicker to digest than complex carbs containing vitamins, nutrients and fiber.

This section is particularly important in sports nutrition for endurance and strength training.

Carbohydrates are split into simple sugars and complex carbs. The difference is their chemical composition, with complex carbs being made up of longer sugar unit chains, as the names describe. Due to the chemical structure of simple sugars, they are absorbed by the body at a much rapid rate, for this reason they are widely used in endurance sports for fueling. Example of simple sugars are glucose, fructose, galactose (these three are monosaccharides and they are the simples form carbohydrates), and added sugars such as cane sugar, brown sugar, nectar, date sugar, high fructose corn syrup, caramel.

Complex carbohydrates have a more complex molecular structure and therefore absorbed at a slower rate by the body. Some complex carbs are made up of branched-chain structures while others are made up of straight-chain structures. This is important because enzymes digest from open end structures, meaning that carbs with branched-chain structures will break down into glucose faster. Therefore, creating a faster blood sugar spike in our bodies. For this reason, the molecular structure of fiber gives it many health befits Including weight loss, reducing risk of cardiovascular disease, bowel movement and intestinal health, diabetes protection absorption of food and in some cases reduces risk of cancer. Some good sources of fiber are oatmeal, beans, apples, artichoke, sweet potatoes, quinoa, broccoli.

Not all calories are made equal, this is especially important when it comes to simple sugars vs complex carbs. Calories from added sugar in candy or cakes do not provide many additional benefits besides 4 calories per gram. These carbs get processed by the body at a rapid rate, creating blood sugar spikes which leave you hungry quicker. The contrast can be found in fruits which have natural sugar; these sources of carbohydrates provide additional vitamins, minerals, nutrients and fiber. This slows down digestion and gives the body energy in a sustained way over a longer period, keeping you feeling satisfied for longer.

Glycogen is the storage molecule of glucose in humans. Glucose is our main source of energy, and therefore plays a very important role in our bodies. Our bodies store a small amount of energy in the form of glucose in our blood, a moderate amount of glycogen in our liver (roughly 350–600 calories worth) and a large amount of glycogen in our muscles (roughly 1,400–1,800 calories worth). When we sleep the brain uses a large portion of the stored glycogen in our liver, making it important to top off those energy stores during breakfast.

When we consume carbohydrates, our body breaks them down into its simplest form glucose, from there the first step is for the body to use this source of energy for immediate needs, followed by storing and replenishing the glycogen levels in our liver and muscles. Any leftover energy then goes through a process called glycolysis. This is the process of converting glucose into fatty acids to be stored in the adipose cells in the form of triglycerides for later use.

The hormonal regulation of glucose plays a key role in our bodies. There are two hormones that play a key role in this process: insulin and glucagon. Both of these hormones are released by the pancreas and they have opposing roles. Insulin facilitates glucose uptake into the liver, therefore lowering blood sugar levels to prevent hyperglycemia. Glucagon facilitates the release of glucose from the liver into the bloodstream, raising blood sugar levels to prevent hypoglycemia.

The glycemic index was created to rank the effect food has on our blood glucose levels 2 hours after consumption. This goes back to the different molecular structures of food sources and how fast it breaks down into glucose. This is an index that goes up to 100, with 100 being glucose. A score of 50 means that food source elevates blood sugar at half the rate of glucose. Low GI foods have a score of under 55, medium have a score of 56–69 and high have a score above 69. A healthy habit is to make yourself somewhat familiar with the glycemic index score of some of the food sources you commonly consume. The glycemic index only tells one side of the story; for this reason, it is also important to understand glycemic load. This basically takes the amount of the carbohydrate consumes into the equation. For example: it is not any better for blood glucose levels to consume 5 times more volume of a lower GI food source, than a smaller amount of a higher GI food source.

It is recommended that we consume 45%-65% of our daily food consumption from carbohydrates, and that we do not exceed more than 10% of our total daily consumption from added sugars. Remember that complex carbohydrates are a good source of vitamins, nutrients and fiber. In your daily consumption, aim to “eat the rainbow”. In other words, look for good sources of carbohydrates from fruits and vegetables, legumes and whole grains. Good examples of these are: oats (with less than 8 grams of added sugar), brown rice, sweet potatoes, quinoa, faro, beans, whole grain bread such as Ezekiel bread, whole grain cereals, bananas, strawberries, mangos, tomatoes, peas, carrots, cucumbers and whole wheat pasta.

I follow the rule of thumb that unless I am consuming carbohydrates during a training session or during my post workout feed window, I try to stay away from anything that has more than 8 grams of sugar per serving.

For endurance athletes, it is important to understand the concept of 3:1 or 4:1 carbs:protein ration. Our bodies rely heavily on glycogen as the main energy source during prolonged periods of exercise. This energy mainly comes from stored glycogen in the muscles and liver. When we are done exercising our bodies are depleted of glycogen, giving carbs the highest level of importance for recovery. Because of the depleted glycogen state of our muscles after exercise, our body upregulates the glucose uptake by the muscle cells up to 50%. This means that if you consume carbohydrates (in particular high GI food sources), the glycogen levels in the muscles will be restored at a faster rate, making it easier and faster to recover and be ready for a strong session later that day or the next day. The longer the exercise period is, the longer this increased rate of absorption will last. The difference between 3:1 and 4:1 ratio depends on the length of the training sessions and the goals of the athlete. The longer the session, the closer it is recommended to be at 4:1 ration; however if the athlete is trying to increase muscle mass then a 3:1 ratio may be more appropriate. As you recall in the protein section, studies have shown that the importance of protein consumption is linked to the total amount of protein consumption as well as the number of times the protein synthesis threshold is crossed, rather than the timing of protein consumption after exercise.


Fat has many important functions in our bodies including being a major source of energy, metabolizing fat-soluble vitamins, and obtaining essential fatty acids.

Fatty acids are broken down into saturated and unsaturated fatty acids which are different in their molecular structures. For this reason, foods high in saturated fatty acids are usually solid at room temperature, like butter, and are often found in animal fat. These food sources tend to have a longer shelf life.

On the other hand, foods high in unsaturated fatty acids are typically liquid at room temperature. They are usually from plant sources and have shorter shelf life. Good sources of unsaturated fatty acids are olive oil, nut butters, sunflower seeds, flax seeds, salmon, and soybean. Unsaturated fatty acids are broken down in to monounsaturated and polyunsaturated fatty acids due to their chemical bonds. Unsaturated fatty acids tend to be considered the healthy fats.

Trans fatty acids is the third and worst category of fats. Trans fats are artificial fatty acids that occur when a hydrogen molecule is forced onto an unsaturated fatty acid in order to make it saturated, to increase its shelf life. Examples of these are margarine, vegetable shortening, fried foods, and non-dairy creamer. These fats increase the risk of cardiovascular disease, raise LDL cholesterol and triglycerides, decrease HDL cholesterol, and increase inflammation. Trans fats cause oxidative damage due to an imbalance of free radicals and antioxidants. It is a good idea to limit your consumption of this fat source.

Essential fatty acids are fatty acids that cannot be synthesized by the human body and, therefore, have to be consumed in our diets. These include both omega-3 and omaga-6 fatty acids, which are polyunsaturated fatty acids. Omega-3s are usually found in fish, seafood, and nuts while omega-6s are usually found in plant oils such as corn and soybean. There are different opinions on the ideal ratio of omega-6/omega-3 for dietary consumption, mostly falling between 1:1–4:1. Unfortunately, due of the popularity of vegetable oils in a Western diet, the average American ratio is closer to 15:1, leading to potential health risks.

Omega-6 fatty acids are considered heart healthy and have shown to reduce inflammation and improve circulation. But many people eat more omega-6 at the expense of omega-3, which have the most benefit. The real answer is to focus on increasing omega-3 fatty acids, rather than reducing omega-6.

However, this ratio can be improved by lower the overconsumption of unhealthy processed vegetable oils (examples are soybean, corn, safflower, sunflower, canola oils) and foods containing these oils. Most packaged and processed food such as potato chips, cupcakes, prepackaged pizza and fried foods contain refined and highly processed vegetable oils. These oils and food sources have more negative side effects than just increasing your ratio of mega6:3 ratio, including increasing inflammation, increased risk of irritable bowel syndrome, and increased risk of cancer and autoimmune disorders.

Good sources of omega 3 fatty acids can be found in salmon, sardines, cod, avocado, wild meat, grass fed beef, flaxseeds, chia seeds, walnuts and soybeans. Increasing your consumption of these food sources will help improve your ratios.

One of my favorite breakfast recipes containing good sources of omega 3 fatty acids and a balanced source of all macronutrients is an oatmeal bowl I eat almost every morning after my morning workout. This recipe comes from one of my training partners, with some of my personal touch. Recipe: Kodiak cakes protein oatmeal (or gluten free oatmeal if I had an easy workout), banana, naked peanut butter powder, flaxseeds, chia seeds, hemp seeds, sunflower seeds, walnuts and syrup. This contains a good balance of low glycemic and high glycemic carbohydrates to replenish glycogen, good sources of omega 3 fatty acids, and more than 20 grams of protein to cross the protein synthesis threshold. I consume this as soon as I am done with my morning training session to ensure it is within my post workout feed window when my body upregulates the uptake of glycogen to the muscles.

Fatty acids are important in the process of transporting and storing lipids in the body. Low-density lipoprotein cholesterol (LDL), also known as bad cholesterol, carries cholesterol from the liver to the cells. High-density lipoprotein cholesterol (HDL), also known as good cholesterol, carries cholesterol from the cells to the liver. Triglycerides are the primary storage of fatty acids in the body and make up most of our adipose tissue.

Good levels of cholesterol are under 200 mg/dL of total cholesterol, under 100 mg/dL of LDL, over 60 mg/dL of HDL, and under 150 mg/dL of triglycerides.

Energy out

Energy balance and metabolism.

It is important to understand the sources and makeup of where we spend our energy (calories out), which we can control and how we can control them.

Every calorie that our body spends is used in the following categories, broken down in a range of percentage of total calories spent.

· Resting metabolic rate: this consumes 60%-75% of the total calories our body spent.

· Thermic effect of feeding: around 10%

· Thermic effect of activity: 15%-30%. This is broken down into Exercising and non-exercising activity thermogenesis. This is the source that can be controlled by us.

Resting metabolic rate is the majority of our calorie expenditure, and this is made up of breathing, circulating blood, organ functions, and basic neurological functions. Some people have very-high resting metabolisms while others struggle with very-low resting metabolisms. High resting metabolic rates may be due in part to a high level of lean body mass (muscle), high production of thyroid hormones, or a variety of other factors. A low thyroid production (hypothyroidism), a high percentage of body fat and low level of lean body mass may all contribute to a low resting metabolic rate.

Thermic effect of feeding is the energy expenditure after consuming a meal. This accounts for the energy required to digest food in order to prepare it for further energy extraction in the body. Approximately 10% of daily energy expenditure is accounted for by the process of consuming, digesting and utilizing food. Simple carbohydrates and fats have relatively low thermic effects of energy compared to protein.

Thermic effect of activity is the area of the energy out equation that we can control. This is broken down into exercise and non-exercise activity thermogenesis. For endurance athletes such as marathoners, triathletes, cyclists, etc., the portion of the exercise activity equation can have a significant effect in calorie expenditure, as some workouts can be 1,000 or more calories per session. For most people the non-exercise portion of the equation is where we can have the most impact. This is energy expended for everything we do that is not sleeping, eating or exercising. It is the energy we consume during daily activities, including walking at work, typing, walking to and from meeting, etc. Having an active lifestyle and incorporating daily activities such as: walking the dogs, walking to the store, standing at a work desk rather than sitting, is where we can see the biggest change in the energy expenditure equation and therefore increase calories out to meet certain goals. Some feasible ways of increasing your calorie expenditure include doing a set of 60 jumping jacks every hour at your desk, doing 10 air squats every hour, taking the stairs to your office, walking around the block after every meal, using a standing desk, taking calls while walking around in your office. There are many easy ways to incorporate low levels of activity into your life that will significantly increase your daily caloric burn.

Navigating the confusing landscape of nutrition can be difficult and intimidating. With the right tools and base knowledge, you can confidently decipher the truth from the myth, the real scientific research versus anecdotal evidence with little scientific supported evidence. This will help you better understand this topic, grow your nutritional knowledge and make the right calls when making dietary and lifestyle decisions. Remember to pay attention to all macronutrients, eat a healthy and balanced diet, assess food sources your consume regularly to understand how they may be impacting your health and pay attention to both sides of the energy equation.