To appreciate how nutrients affect the body it is important to first understand the following basic nutrition concepts. There are six nutrient groups: carbohydrates, proteins, fats, vitamins, minerals, and water.
The nutrients that provide energy are carbohydrates, proteins and fats (also called “macronutrients”. Macronutrients are essential calorie-containing nutrients (your body needs them to operate properly) that are needed in relatively large amounts.
Micronutrients (vitamins and minerals) are not a source of energy, but they help your body produce energy from the foods you eat and are needed in relatively small amounts.
Carbohydrates
Contains 4 calories per gram and is digested quickly and turned into glucose. Known as the “energy powerhouse” because they are what our bodies (especially our brains and muscles) need for fuel. Carbohydrates are the most important nutrient for hard-working muscles.
If adequate amounts of carbohydrates are not consumed, skeletal muscle will be used to synthesize glucose for the brain. The foods that provide carbohydrates are dairy (milk and yogurt), fruits, grains, starchy vegetables, sweets and many processed foods. Carbohydrate-rich foods such as whole grain and cereal products, fresh fruits, starchy vegetables, and legumes are also typically excellent sources of fiber.
Vitamins and minerals are abundant in many of these foods, making them “nutrient dense” food choices. We can store carbohydrates in the body (as glycogen in muscles and liver) but we also need to maintain a certain amount in our bloodstream (glucose) to give us energy.
There are two types of carbohydrates: simple (refined sugars, fruit juice, processed grains), and complex (whole grains, whole fruits and starchy vegetables). Complex carbohydrates take longer to convert to glucose due to the presence of fiber, keeping blood sugar levels consistent and preventing an energy crash in the middle of training.
Most sports dietitians recommend that at least 50% of carbohydrates consumed are in the form of complex carbohydrates/whole grains. Too little carbohydrates (less than 45%, or less than 100 grams per day), can cause a person to feel faint, dizzy, weak, have trouble concentrating or be unable to participate fully in physical training.
Protein
Contains 4 calories per gram and is digested quickly. Amino acids are the building blocks of protein, necessary to build and repair muscle tissue, grow hair and fingernails, produce hormones, fight infection and replace red blood cells.
There are 20 dietary amino acids of which 9 amino acids are not made by the body and are considered essential amino acids that must be consumed through the diet. Animal products provide all the essential amino acids and are considered a “complete” protein.
Plant based sources, quinoa and soy, are also considered a “complete” protein because they contain all 9 essential amino acids. Animal products like beef, poultry, pork and fish are not the only source of protein; vegetable-based options exist, including beans, nuts, lentils, edamame and tofu.
Protein is available in all food groups except fruit and solid fats. Low fat and nonfat animal and dairy products are good sources of protein. Grains and vegetables are moderate sources of protein. It is true that protein is needed for the development of muscle, but it is not true that “more” protein will build bigger muscles.
Excess protein is either burned for energy or stored as fat. Human bodies do not store protein, so adequate portions need to be consumed daily but should not exceed recommended daily intakes. Eating too much protein can lead to a number of problems, including dehydration (from frequent urination to get rid of the waste generated from protein digestion), an unbalanced diet (displacing carbohydrates in the diet) and possibly increased calorie and fat intake.
The general guideline for healthy individuals is roughly 0.4 grams of protein per pound of body weight depending on activity level. For resistance training individuals this number can be up to 0.8 grams of protein per body weight. A 150 lb. person would need 60 grams of protein per day. The majority of Americans easily meet their daily protein needs from the foods they eat.
Fats
A rich source of energy contains 9 calories per gram, twice that of carbohydrates and protein. Excessive dietary fat can lead to weight gain, heart disease, and cancer, however, some fat is actually necessary and beneficial.
Fat is an important precursor to hormone production such as estrogen, cholesterol and testosterone. Fat digests slowly and provides a source of energy for moderate intensity and/or long duration physical activity, builds cell walls, transports and stores fat-soluble vitamins, insulates and protects vital organs, and makes food taste better.
It is important to pay attention to the types of fats you consume. There are three types of fat; monounsaturated, polyunsaturated, and saturated. Another type of fat trans-fatty acids is produced commercially and should be avoided. Saturated fat should be eaten in moderation.
Trans-fatty acids are usually found in commercially baked foods and can be distinguished from reading the nutrition label ingredients looking for the key words hydrogenated oils or partially hydrogenated oils.
Saturated fat comes mostly from animal products and can be reduced by choosing reduced fat, low-fat or non- fat animal and dairy options. These fats are solid at room temperature (e.g. butter). Small amounts of healthier fats, called mono and poly unsaturated fats, can improve heart health.
They are mostly found in plant foods such as olive oil, canola oil, peanut oil, avocados, and most nuts. Fatty fish such as tuna and salmon are a good source of these healthy fats, too, and may play an important role in cognitive health. These fats are liquid at room temperature (e.g. olive oil.) Body fat storage varies from person to person, based on many factors including gender (women typically store more fat than men for biological reasons).
Even a fairly lean individual has reserves of stored fat. For example, a 150-pound person who has 10 percent body fat has about 62,000 calories stored as fat (this is why you can live much longer without food than without water). Since the body’s fat storage is more than adequate to provide reserve energy, only a small amount of dietary fat is needed.
In fact, a diet that is moderately low in fat (20-35 percent of total calories from fat) is recommended and will promote an eating style that will be beneficial throughout life for both physical performance and overall health.
Water
Water is essential for life, the human body is made up of over 50% (the exact % is different for males and females and also from one person to another). Water has no energy (calorie) value, but is needed to transport nutrients throughout your body, through blood, aid in digestion, and eliminate waste.
Training places great demands on fluid replacement; proper hydration before, during and after intense workouts is critical. Individuals who fail to keep up with their water requirements not only jeopardize their performance, but also put themselves at risk for decreased performance, heat cramps, heat exhaustion, stroke, and death.
There is a simple calculation to determine water intake: divide your body weight in half and that’s how many ounces, at the very minimum, you should be drinking every day. For example, a 150 lb person should be drinking at least 75 ounces (about 10 cups) of fluid per day.
The simplest way to tell if you are adequately hydrated is the urine test. Drink enough water so that your urine is consistently pale yellow/light lemonade color and weakly scented. Water is the best beverage for hydration. Sport drinks can help replace electrolytes during strenuous exercise exceeding 60 minutes. Other fluid sources include fresh fruit, broth-based soups, juices, milk, and fresh vegetables.
Basic Military Training Hydration Schedule
- Drink ¾ to 1 water bottle every hour and do not exceed 16 water bottles in one day (to keep you from becoming dehydrated and to prevent over-hydration)
- Do not drink more than 2 water bottles in a one-hour period (to prevent over-hydration)
- Drink fluids before you become thirsty (even during winter months) and continue even after your thirst is quenched. Thirst is the first sign of dehydration
- A simple urine check will show if you are properly hydrated (refer to the hydration chart in your dormitory)
Vitamins and Minerals
These micronutrients are essential because they cannot be made by the human body; they must be obtained from foods. There are more than 30 essential micronutrients that play an important role in making hemoglobin, maintaining bone health, supporting immune function, and protecting the body against oxidative damage.
They assist with the building and repair of muscle tissue during recovery from exercise and injury. Micronutrients are essential for optimal cognitive and physical performance as well as long term health and bodily function. Vitamins are divided into two main groups, fat-soluble and water-soluble.
Fat-soluble vitamins (A, D, E and K) need fat in the diet to be absorbed and are stored in your body. Excessive consumption or supplementation can lead to toxicity Vitamin D is critical to keeping bones healthy and strong. Water-soluble vitamins (C and B-complex) dissolve in water and are not stored in the body.
Since your body cannot store them, you must replenish them daily. Minerals are divided up into major and trace based on the amount needed to be consumed by the body. Minerals such as iron and calcium are especially important during BMT to prevent extreme fatigue, maintain healthy bones, and reduce risk of injury.
Iron, a trace mineral, is involved in building red blood cells and transporting oxygen around your body so that the brain can maintain cognitive function and muscles can continue exercise. Calcium, a major mineral, helps build strong bones, teeth, muscles and regulates your heartbeat.
Eating a balanced, nutrient dense diet is the best way to get vitamins and minerals. Military men and women in training have higher requirements for iron. Increased iron needs during military training can be higher for women, and can be difficult to meet with diet alone.
Although food is the best source of vitamins and minerals to meet needs, a daily multivitamin/mineral with iron is offered during BMT to assure iron needs are met. Men and women in BMT may be prescribed a nutrition prescription for anemia when needed based on laboratory results.
A multivitamin not only ensures necessary iron in men and women, but it also provides additional calcium and vitamin D. Vegetarians and those with lactose intolerance are vulnerable to higher risk and injury. The multivitamin could be very beneficial to these individuals.