Calories
What Are They and What Are They For?
They serve to perform all bodily functions that require energy. Calories are not a tangible object but are basically a measurement of energy.
Use of Calories in the Body
In the body we use energy from the breakdown of food molecules to power different systems, such as the nervous and muscular systems.
Where Are Calories?
Basically all food has usable caloric content — what varies is the caloric density (amount of calories) of each food. There are foods with caloric contents so low they cannot be quantified, and others that are essentially pure energy.
How Is the Energy Content of a Food Determined?
The amount of energy (calories) contained in a food and the amount of energy used for any bodily function is measured by incinerating said food. Since 1 calorie equals the energy needed to raise one kilogram of water exactly 1 degree Celsius, after incinerating a food and measuring the temperature difference in the water, the caloric content of that food is obtained.
Daily Requirements
Without exercise, humans need between 1,400 to 2,000 calories.
- Basic bodily functions: To stay alive — maintaining our heartbeat, keeping our nervous system and organs functioning — we can use an average of 1,100 to 1,400 cal daily.
- Daily activities: The modern sedentary human can spend between 400 to 600 cal on daily activities.
- Exercise: Caloric expenditure in exercise can vary between 200 to 1,000 cal, and even in competitions like IRONMAN, more than 7,000 cal can be burned.
Water
What Is It and What Is It For?
Water, among many functions, regulates body temperature, transports nutrients, and represents up to 70% of body weight.
Use of Water (H₂O) in the Body
It serves to transport all nutrients in the body and is the essential basic component of blood. It also helps regulate body temperature and is the most important basic nutrient for survival.
Where Is Water?
We find it from a glass of pure water to soups, fruits, and even grains and meats — water is in every food we consume.
Daily Requirements
On average 2.4 liters of water daily plus what's lost during exercise.
- Basic bodily functions and daily activities: Women typically need 2.3 liters daily while men need 2.7 liters. Some sources mention consumption as low as 1.7 liters daily.
- Exercise: Water use in exercise depends on many factors, mainly ambient temperature, body temperature, and exercise intensity. Through sweat we can lose several liters of water, therefore consumption before, during, and after training is essential.
How to Determine Water Loss
To determine water loss and therefore water needs during exercise, it's necessary to take your weight before and compare it with your weight after the activity (taking into account any intake during exercise). If we lost, for example, 1 kilogram during an exercise session, we should replenish 1 liter of water. It's recommended to consume 150% of body weight lost during exercise in water.
Carbohydrates
What Are They and What Are They For?
They serve to provide energy to body systems such as the muscular and nervous systems.
Use of Carbohydrates (CHO)
The nervous system (brain and nerves) depends directly on carbohydrates to function properly. Muscles depend on them to contract.
Where Are Carbohydrates?
Cereals, fruits, starchy vegetables — carbohydrates are widely present in foods. Dairy contains carbohydrates, sugars are carbohydrates, beverages also contain carbohydrates. In fact, some of the few foods that don't usually contain high amounts of carbohydrates are meats and seeds.
Daily Requirements
From 50 to 70% of diet calories should be from carbohydrates.
- Basic bodily functions and daily activities: 50% of daily calorie consumption should come from carbohydrates in people who are not physically active.
- Exercise: Carbohydrate consumption should increase along with activity level, frequency, and intensity. Up to 70% carbohydrate consumption is recommended for people who do aerobic exercises — basically 8 to 10 grams of carbohydrates per kilogram of body weight. Those who only lift weights need only 5 to 6 grams per kilogram. However, these figures vary greatly according to the individual, which is why it's necessary to monitor weight and body composition.
Proteins
What Are They and What Are They For?
They serve for muscle reconstruction, cellular structure, and tissue formation. In certain occasions, they can also serve as an energy source.
Use of Proteins
Proteins are used in the body to give structure to many tissues. For example, from nails and hair to the cell wall — all are composed of proteins. However, proteins are mainly known for participating in muscle recovery.
Main Protein Sources
- Animal proteins: Meats, dairy, and eggs
- Plant proteins: Legumes, seeds, and cereals
Proteins can be divided into two main groups: low-quality proteins and high-quality proteins. They are named this way based on their amino acid content. Low-quality proteins contain low levels of amino acids essential for the body, while high-quality proteins contain all the amino acids necessary for muscle recovery and other functions. Plant proteins mainly contain low-quality proteins while animal proteins are high quality.
Protein Quantity Equivalence
A common mistake is believing that meat or milk is all protein, when they really only contain 40% to 10% protein. For example, a piece of red meat of 100 grams may only have 30g of protein, while a glass with 250ml of milk may only have 8 grams.
Daily Requirements
From 0.8 grams per kilogram of body weight for sedentary people to 2 grams for weightlifters.
- Basic bodily functions and daily activities: Due to less tissue damage, sedentary people need only 0.8 grams per kilogram. This means a person weighing 65 kilos needs only 55 grams of daily protein.
- Aerobic exercise: Practitioners need between 1.2 to 1.4 grams per kilogram of body weight — that would be about 100 grams of protein for a 65kg runner.
- Weightlifting: Requires up to 2 grams per kilogram of body weight. For example, a person who trains at the gym and weighs 80kg needs 160 grams of protein to recover their muscles.
Fats
What Are They and What Are They For?
They serve to regulate hormonal processes, transport vitamins, have cardio-protective functions, and are used as an energy source.
Use of Fats
Fats transport and regulate hormonal levels, serve as an energy source. Some monounsaturated fats perform cardio-protective functions while some polyunsaturated fats are essential and must be consumed for normal body functioning.
Different types of fats serve different functions. In general, all can be used as an energy source. Trans fats are not essential. Saturated fats and cholesterol at elevated levels can cause cardiovascular problems, while monounsaturated and polyunsaturated fats have the opposite effect.
Fat-Rich Sources
Oils, margarines, mayonnaises, avocado, seeds, coconut, meats, and dairy.
Daily Requirements
Between 15 to 30% of total daily caloric intake.
- Basic bodily functions and daily activities: Really low amounts of fat are required to perform main hormonal and cardio-protective functions — as low as 4% of total calorie intake. However, consumption below 15% of total caloric intake is not recommended.
- Exercise: Fats are an important energy source and promoters of hormonal processes necessary for muscle recovery like testosterone production. Therefore, requirements can reach 20%, 30%, or even higher if carbohydrate intake is regulated to compensate for fat consumption.
Vitamins and Minerals
What Are They and What Are They For?
They are nutrients used in extremely varied functions, ranging from regulating metabolic processes, preventing cell destruction, bone formation, nerve function, disease prevention, immune system, among others. These micronutrients are involved in all bodily processes.
Deficiency Anemia
Low consumption of any vitamin or mineral can trigger health disorders as varied as yellowish skin to muscle cramps or deficient blood clotting.
Daily Requirements
Requirements are minimal, at microgram scales for several vitamins and minerals. For this reason, it's accurate to say the necessary daily dose is easily achieved with daily consumption of foods from all primary sources — mainly fruits, vegetables, meats, dairy, and water.
- Vitamins: Are necessary only in normal doses for athletes, since there is no additional benefit in performance with consumption above regular levels. Even so, some important vitamins for athletes are C, D, and E.
- Minerals: Have been shown to be useful for athletes, improving performance with normal consumption and increasing it even more with elevated consumption above the recommendation for sedentary individuals. For example, sodium can increase performance by up to 10% in long-duration endurance exercises, and zinc consumption reduces the potentially negative effect on the immune system after an exercise session.
Source: ACSM, National Academy of Sciences
Important Warning
It is extremely important to remember that excessive consumption of vitamins and minerals leads to health problems. Therefore, both athletes and sedentary individuals should only seek to consume foods from different sources to meet all needs and not fall into excessive consumption through exaggerated supplementation.
References
- World Health Organization (WHO). Nutrition guidelines and requirements.
- National Strength and Conditioning Association (NSCA). Essentials of Strength Training and Conditioning.
- International Society of Sports Nutrition (ISSN). Position stands on protein and carbohydrate intake.
- United States Department of Agriculture (USDA). FoodData Central nutritional database.
- American College of Sports Medicine (ACSM). Exercise and fluid replacement position stand.
- National Academy of Sciences. Dietary Reference Intakes for vitamins and minerals.