Nutrition

Functional, sustainable nutrition habits are critical for living a healthy life. You can’t exercise enough to make up for eating poorly¹ so, at the very least, you must eat well enough for a solid foundation. The key characteristics of a good diet are:

1. It keeps you in the right energy balance to achieve your goals.
2. It provides enough protein to help you build muscle.
3. It promotes metabolic health by avoiding spikes in blood sugar and the subsequent insulin response.
4. It is enjoyable enough that you can maintain adherence over time.

Mindset

Science can provide the foundation for functional nutrition and the framework to make deliberate modifications. However, just as it is in training, your nutritional needs are unique to you, the activities you engage in, and your life situation. You will need to experiment, observe, and make refinements to determine what works best for you.

The information compiled here attempts to distill practical applications of nutritional science. However, it can be easy to get lost in the weeds, chasing down details that aren’t important, if science is your only tool. The opening of Mastering Mindful Eating by Michelle Babb contrasts the “art” of eating with the science of nutrition. The art of eating embraces the experience of eating and listening to your body; practices like this are a reminder to invest in your holistic health. Don’t just optimize metrics; live your life.

Energy Balance

Energy balance is the relationship between the amount of energy your body needs and the amount of food you eat each day on average.

• A positive energy balance means you are eating more than you need.
  • It is easier to build muscle in a positive energy balance.
  • Your body stores excess energy in adipose tissue (fat) when you maintain a positive energy balance.
• A neutral energy balance means you are only eating enough to maintain your current body weight.
  • You do not need to adhere to a precise number of calories per day to be in a neutral energy balance. Your body has about 400–600 calories of “wiggle room” on a daily basis.²
• A negative energy balance means you are eating less than you need.
  • Muscles waste away faster in a negative energy balance.
    • You can limit the disproportionate loss of muscle mass by maintaining a deficit at or below 400 calories per day.
  • Your body uses up the excess energy stored in adipose tissue when you maintain a negative energy balance.

The amount of energy your body burns each day depends on your activity level, your genetics, your gut microbiome, and a host of other factors. It’s difficult and unreliable to guess your energy needs and you should not put any stock in any estimated “exercise calories” numbers generated by fitness trackers or gym equipment.

The only way to get an accurate idea of what your energy needs are (outside of a stint in a metabolic ward) is to carefully and precisely track all of the things you eat (use a scale!) and record your weight over time.³ Once you know your total daily energy expenditure (TDEE) and your desired state of energy balance you can determine your daily calorie target. Your caloric budget can then be divided into target amounts for the three macronutrients.

Macronutrients

There are three dietary macronutrients (called “macros” colloquially):

• Carbohydrates are sugars and starches.⁴
  • Carbohydrates are the primary source of fuel for your body.
  • When you are in positive energy balance, and especially if you are in poor metabolic health, your body uses carbohydrates as fuel almost exclusively.
• Protein is made up of amino acids; it is primarily used to build the proteins your body needs.
  • Protein can be used as fuel but it isn’t very efficient; your body favors other sources of energy.
  • Protein deserves special attention for its role in building and maintaining muscle.
• Fat is made up of fatty acids and, in metabolically healthy people, it can be used as fuel—especially when you’re in a negative energy balance.
  • Dietary fat is easy for your body to store as adipose tissue if you are in a positive energy balance.

Carbohydrates and fats are used as fuel or stored for later. Protein is used to build, repair, and replace tissues, cells, and cellular structures.

Carbohydrates

Carbohydrates are a class of nutrients that are similar in chemical structure but vary in complexity. Sugars are the simplest and are digested the fastest. Starch is the most complex and must be broken down into sugars before it can be further digested.

Carbohydrates are a critical part of a functional diet. Do not avoid eating them to be “healthy.” Consumption of refined carbohydrates like white flour and added sugar can impact your metabolic health and should be done in moderation. Favor longer-digesting, lower glycemic index sources of carbohydrates like whole grains (it’s best if they’re not ground into flour), legumes (beans, lentils peanuts), sweet potatoes, cruciferous vegetables, and others too numerous to list here. Eating carbohydrates in combination with fat, protein, and fiber helps regulate their digestion and absorption.

The common dietary sugars are glucose and fructose. Table sugar is about a 50/50 mix of glucose and fructose while high-fructose corn syrup is 60% fructose and 40% glucose. Glucose and fructose are metabolized in different ways.

• If you’re trying to maximize carbohydrate intake—like during an endurance race that lasts longer than 45 minutes—consume a balance of glucose and fructose.
  • Fructose metabolism is different between men and women; women should avoid fructose as an endurance fuel.
• Fructose is preferentially turned into adipose tissue.⁵

The liver uses carbohydrates to create and store glycogen which your body uses to maintain glucose homeostasis during long bouts of exercise. Endurance athletes “bonk” when they run out of glycogen and the nutrients they’re absorbing from the food they’re eating during the activity can’t keep up with their energy (and/or electrolyte) needs.

Protein

You can vary the distribution of carbohydrates and fat in your diet to meet your energy needs but your body requires a certain amount of protein intake to maintain muscle mass and even more to promote increasing muscle mass. Since growing your muscles is critical for your long-term health, you must pay attention to your protein intake. To do this, you must consider:

• The total amount of protein you eat.
  • Your body needs about 300g of protein per day to support necessary metabolic processes.
    • Your body can get up to 50% of the protein it needs through recycling what it already has.
    • As you age, the rate you can recycle protein goes down so you need a corresponding increase in dietary protein to prevent being in a protein deficit; the decline isn’t linear, there is a sharp drop off after age 40.
  • A daily target of 1.2–1.8 g/kg/day of dietary protein maximizes muscle protein synthesis.
    • The RDA for protein is .8 g/kg/day. This is too low to support training and muscle growth.
    • 1.4–1.8 g/kg/day is ideal. Above 1.4 g/kg/day the quality of the protein you eat matters less.
    • Some fitness influencers advocate for 1g/lb/day of high-quality protein (2.2 g/kg/day). This is way more than you need.
  • A serving of protein that you’re digesting is called a bolus.
    • The minimum effective size of a bolus is around 25g; smaller servings don’t activate mTOR.⁶
    • The maximum effective size of a bolus is around 60g; any more is discarded as waste.
    • You should split your protein consumption into 3–4 different feedings for best absorption.
• The “quality” of the protein you eat.
  • The three most important amino acids for muscle protein synthesis are leucine, lysine, and methionine.
    • Leucine in particular is critical; aim for ≥3g of leucine in the first and last meals of the day (this usually requires about 45g of protein but the exact amount depends on the amino acid distribution of what you’re eating).
    • FUN FACT: Leucine is ketogenic; it is metabolized as a fatty acid because of its structure.
  • The quality of the protein you eat matters less the more protein you eat.

The main takeaway here is that you need to eat a lot of protein to support growing and maintaining muscle—almost assuredly more than you would eat without being deliberate about it.⁷

Fat

Fat is an essential nutrient. Your body requires enough dietary fat to support a healthy endocrine system as fat is an essential ingredient for hormone production. Dietary fat intake can also impact many areas of brain function; it is necessary for cognitive health.

Most people eat too much total fat while simultaneously not eating enough of specific kinds of fat.

• Polyunsaturated fats, including omega-3 and omega-6 fatty acids, have clear long-term health benefits when consumed regularly in sufficient quantity. Good sources of polyunsaturated fat include sunflower seeds, flax seeds (and oil), algae oil, and wild-caught⁸ fatty fish like salmon, herring, mackerel, etc. Most people don’t get enough in their diet without supplementation or deliberate planning.
• Saturated fat should be eaten in moderation as it contributes to the risk of atherosclerotic cardiovascular disease (ASCVD).
• Artificially created trans-unsaturated fatty acids (trans fats) are very bad for ASCVD. Avoid partially hydrogenated oil and other sources of trans fat in your diet.
• Dietary cholesterol is almost exclusively esterified cholesterol. Esterified cholesterol molecules are too large to be absorbed in your digestive system; they are just excreted. Dietary cholesterol has NO IMPACT on blood cholesterol.
• Medium-chain fatty acids, like MCT oil, can be easily metabolized into ketones which your brain can use as fuel. They can give you a bit of a mental boost in your morning coffee.⁹

Your body preferentially uses carbohydrates as fuel. Fats are left in reserve unless you sustain a negative energy balance over time or eat so few carbohydrates you enter and maintain ketosis. Using fat as your primary fuel can be helpful in specific situations:

• For endurance athletes in extremely-long-duration events.
• As an augmentation to a cancer treatment plan for cancer patients; cancer cells can multiply at a prodigious rate because they can metabolize up to 500 times more glucose than a normal cell. Starve them and it gives other therapies a competitive advantage.
• As part of a targeted, short-term fat-loss program.

Ketogenic (“keto”) diets aren’t a great idea in the long term.

• It is easy to have a high saturated fat intake which, as noted above, is bad for the long term health outcomes.
• They forbid many kinds of food and require a lot of food prep so they are prone to diet fatigue.
• Things go off the rails easily. If you eat enough carbs to get out of ketosis while eating a lot of fat it’s not a good situation.
• Your liver is responsible for producing the ketones your body needs as fuel while in ketosis. Drinking alcohol can compromise its ability to do that.
• In general, it’s not a good idea to eliminate one of the three macronutrients from your diet.

Physique athletes, like bodybuilders, must maintain a very low fat intake to get to competitive levels of leanness. This can cause all kinds of issues as you’re depriving your body of an essential nutrient. There may not be any long-term consequences for doing this occasionally but you can’t maintain extremely low levels of body fat and have good long-term health outcomes.

Micronutrients

Macros aren’t everything. Your body needs lots of different vitamins and minerals in trace amounts. It’s tempting to use supplements to meet these needs but it’s better to get micronutrients from real, minimally processed food if you can.

The supplement industry is loosely regulated and rife with bold claims that are hard to verify. Ask yourself these questions before taking a supplement:

• Are you getting a large enough dose for it to have a meaningful effect?
• How does the bioavailability of the form or the micronutrient in the supplement compare to food sources?
• Do you need additional nutrients to effectively process it?
• How consistent is the supplement potency from batch to batch?
• High-quality supplements are expensive. Are they worth the cost to you for the benefit they provide?

You will probably benefit from some supplementation depending on your training needs. Examine.com is a good place to start your research. However, figuring out which supplements and how much to take for your specific situation can be tricky to figure out on your own. Talk to a nutritionist—ideally with credentials in sports nutrition—if you can.

Fiber

Dietary fiber helps digestive health and, in general, is a good proxy for seeing if you’re eating enough minimally processed fruits and vegetables. The RDA for fiber (28g per 2000 calories) is almost assuredly more than you are eating now unless you’re being deliberate about it.

The fiber in your diet that comes from food helps regulate nutrient and sugar absorption in addition to being good for your GI health. Fiber supplements, in pills or added to processed food, don’t do the same thing.

Metabolic Health

Metabolically healthy people can switch between using glycolytic (glucose-based) energy sources and fatty-acid-based energy sources. Metabolic health is underpinned by mitochondrial function. Mitochondrial function is improved by endurance training and, unless you are currently doing several hours of endurance training a week, you are almost certainly not metabolically healthy.

Metabolic health is also influenced by diet. Specifically, spikes in blood glucose—and the corresponding spikes in insulin response—can be moderated with dietary factors:

• The total amount of carbohydrates in your diet.
  • One rule of thumb is to keep carbohydrates to less than 30g/meal to dampen insulin response.
• The glycemic index of the carbohydrates you consume. The higher the glycemic index the faster sugar enters your bloodstream.
  • Carbohydrates in unprocessed foods, like vegetables, are stored in and around dietary fiber which slows their digestion.
  • Processed, and especially hyper-processed, foods digest faster which causes spikes in blood sugar.
• Energy balance also plays a role in metabolic health.
  • Maintaining a negative energy balance can adversely affect your metabolic health because your body reacts to the calorie deficit by slowing your metabolism.
  • Maintaining a positive energy balance means your body is far more likely to only use glycolytic energy sources for fuel; this effect is more pronounced the larger the energy surplus. Many diabetic and pre-diabetic people have lost the ability to use fatty acids as fuel and thus depend solely on energy from the sugar that’s wreaking havoc on their overall health.

The factors listed above all point to the benefits of moderation. Tempering the amount and the speed at which sugar enters your bloodstream helps your body maintain glucose homeostasis without having to work too hard. Keep your pancreas and your liver happy; they’ll thank you for it later in life.

Your blood sugar levels are a good proxy for understanding your metabolic health. The most accurate way to track your blood glucose is with a continuous glucose monitor (CGM) like the ones made by Dexcom.¹⁰ Because they can be used to administer insulin as medical devices, CGMs aren’t readily available to consumers unless you have a prescription from your doctor.

Palatability & Pleasure

Eating good food is one of life’s simple pleasures. If you don’t enjoy what you’re eating enough then you cannot to sustain your eating habits for the long term. The trick is finding the right balance between:

• Meeting your nutritional needs
• Exercising enough
• Having times when you can enjoy yourself

The most important thing is to find the food you like to eat that meets your nutritional needs. Changing your diet can change your palate¹¹; what you like in the future may not be the same things you crave now. And, even when you’re eating the kind of food you need consistently, it’s still a good idea to have the occasional meal or, or day, where you eat whatever makes you happy.¹²