http://www.ocs.usmc.mil/New_Web_Format/Can...n/Nutrition.htmNUTRITION
Good nutrition is essential to prepare you for the intensive training you will receive at OCS. The following information is included as a guide to assist you with understanding the role of macronutrients, micronutrients, vitamins, and minerals in diet as well as to understand the best sources and foods to obtain these nutrients. Also included is information regarding weight loss, the importance of nutrition in exercise and “fad” diets. All of these issues are relevant in maintaining military readiness, force health protection, and in promoting optimal health of military personnel. There is a separate link that gives examples of sample menus to follow. More information about nutrition and fitness can be obtained by clicking on the link to the Navy Environmental Health Center (NEHC) at
http://www-nehc.med.navy.mil/hp/index.htm Energy Balance
The difference between energy intake, how many kilocalories (kcal) we eat, and energy expenditure, how many kcal we burn, is termed energy balance. Eating the same number of kcal as you burn leads to a net energy balance of zero, and your current weight is maintained. Eating more or less kcal than you burn leads to positive (weight gain) or negative (weight loss) energy balances, respectively.
There are six classes of nutrients: carbohydrates (CHO), proteins, fats, vitamins, minerals, and water. carbohydrates, proteins, and fat, also called macronutrients, are the energy providing nutrients. Vitamins and minerals, also called micronutrients, are needed in small amounts to help in energy metabolism. Water is the most abundant nutrient in the body and is essential for the normal functioning of all the organs in the body.
Energy Providing Nutrients
Carbohydrates, proteins, and fats provide energy. While there is much debate when it comes to the ideal percentage of daily kcals from these macronutrients, the Dietary Reference Intakes (DRI) set by the Institute of Medicine’s Food and Nutrition Board in 2002 are as follows:
CHO: 45% to 60% of total daily kcals
Fats: 20% to 35% of total daily kcals
Proteins: 10% to 35% of total daily kcals
Carbohydrates
Carbohydrates are found in grains, fruits, and vegetables and are the main source of energy in a healthy diet. Unfortunately, many people think carbohydrates are unhealthy and lead to weight gain. That notion came about because most people add high-fat toppings and sauces to their starchy foods. The types of carbohydrates are:
Sugars - have one (mono-) or two (disaccharides) sugar molecules hooked together. Examples include: glucose, tablesugar (sucrose), sugars in fruit (fructose), honey (fructose and glucose), sugar in milk (lactose), maple syrup, and molasses. Some are added in processing. Added sugars provide kcals and no nutrients.
Starches and Fiber - Starches have three or more sugar molecules hooked together that are broken into smaller sugar molecules when digested by our bodies. Examples include: whole grains, fruits, vegetables, and legumes (peas, beans).. Dietary fiber is edible, but nondigestible component found in plant foods. Although, dietary fiber does not provide any kcals, low intakes of fiber are associated with higher risk of heart disease. For this reason, it is recommended that men and women under the age of 50 years eat 38 and 25 grams of fiber a day, respectively. This is achieved by eating more fruits, vegetables, and whole grains
Carbohydrates are used in the body to:
Provide energy in the form of glucose (stored as glycogen).
Provide fuel for the brain.
Act as building blocks for chemicals needed by the body.
Repair tissue damage in the body.
Proteins
Proteins are found in meat, fish, poultry, and dairy foods. Beans and grains also provide proteins but in smaller amounts than animal foods. All proteins are made of various amino acids that are joined together. There are 20 different amino acids. Nine of these are called essential amino acids because the body cannot make them, so they must be obtained from the diet.
Proteins are used in the body to:
Form muscle, hair, nails, skin, and other tissues.
Provide energy.
Repair injuries.
Carry fats, vitamins, and minerals to different parts of the body.
Contract muscle.
Serve a structural role for every part of the body.
Energy from Proteins
Your protein needs are determined by your age, body weight, and activity level. Most people eat 100 to 200 g of proteins each day, which is more protein than is actually needed by the body. Actually, these excess kcals from proteins can be converted to fat and stored. Although proteins provide energy, they should not be the main dietary source of energy. High-protein intakes also increase fluid needs and may be dehydrating if fluid needs are not met. In addition, high-protein intakes put the kidneys under great strain in order to get rid of all the breakdown products.
Fats
Fats are an essential part of your diet, regardless of their bad reputation. However, not all fats are created equal. By knowing about the different types of dietary fats and using the guidelines for daily fat consumption, you can eat the right amount of fat. The three types of fats naturally present in foods are saturated, and mono- and polyunsaturated fats. A fourth type of fat is trans fat and is created during the processing of some foods.
Saturated Fats are solid at room temperature and are found primarily in animal foods (red meats, lard, butter, poultry with skin, and whole milk dairy products); tropical oils such as palm, palm kernel and coconut are also high in saturated fat.
Monounsaturated Fats are liquid at room temperature and are found in olive oil, canola oil, and peanuts.
Polyunsaturated Fats are liquid at room temperature and are found in fish, corn, wheat, nuts, seeds, and vegetable oils.
Saturated, monounsaturated, and polyunsaturated fats should each be less than or equal to 10% of your total daily kcals. Therefore, total fat intake should be less than or equal to 30% of your total daily kcal intake.
Trans Fats are created during manufacturing by a process known as hydrogenation. This process converts unsaturated fats to saturated fats. Manufacturers hydrogenate foods to improve the shelf life of their products. Currently, food labels do not list the trans fat content of a food but if “hydrogenated oils” are listed under ingredients it indicates the presence of trans fats. The more processed foods you eat the greater your trans fat intake. Trans fats may increase blood cholesterol. A high-fat diet is associated with many diseases, including heart disease, cancer, obesity, and diabetes. On average, people who eat high-fat diets have more body fat than people who eat high-carbohydrates, low-fat diets. On the other hand, a fat-free diet is also very harmful since fat is an essential nutrient required by the body.
Fats are used in the body to:
Provide a major form of stored energy.
Insulate the body and protect the organs.
Carry other nutrients throughout the body.
Cholesterol
Cholesterol is a part of body cells, and serves as a building block for some hormones (e.g., testosterone and estrogen), and it is required to digest fats. The body makes cholesterol in the liver. Cholesterol is also consumed in the diet by eating animal products. A diet high in dietary cholesterol and saturated fats is associated with an increased risk for heart disease. The American Heart Association recommends that daily cholesterol intakes do not exceed 300 milligrams. Red meats and egg yolks are cholesterol rich foods that should be consumed in moderation.
Micronutrients - include all vitamins and minerals. Neither provides any kcals but both facilitate metabolism (the chemical breakdown) of the macronutrients. Specific functions of micronutrients are listed in Table 2-2 and Table 2-3.
Vitamins - are classified as fat or water-soluble.
Fat Soluble Vitamins are absorbed with dietary fat, can be stored in the body, and are not excreted in the urine. These include vitamins A, D, E and K.
Water Soluble Vitamins, including the B vitamins and Vitamin C, are not stored in the body in appreciable amounts and excess amounts are excreted in the urine each day.
Minerals - are classified according to their concentrations and functions in the body. Examples include: calcium and magnesium.
Trace Minerals - are less abundant than minerals; examples include: zinc, copper, and iron.
Electrolytes - examples include sodium, potassium, and chloride.
Recommended Dietary Allowances
The Recommended Dietary Allowances (RDA) are the amounts of the vitamins and minerals, respectively, that a healthy person should eat to meet daily requirements. The RDAs are designed to meet the daily requirements for most healthy people. The RDAs are undergoing revisions and new standards are gradually becoming available. These new standards are called the Dietary Reference Intakes (DRI). The military has also developed a set of allowances known as the Military DRIs (MDRIs) to be used for designing military rations. In most cases your micronutrient needs will be met by eating a variety of foods. Taking multivitamin and mineral supplements is another way to meet the RDAs for the micronutrients. However, if you elect to take micronutrient supplements, you are urged to take only the RDA amount for each micronutrient. Taking more than the RDA of a micronutrient could lead to toxicity and create deficiencies of other micronutrients.
Micronutrients in the Diet
No one food can provide all of the micronutrients, so you are encouraged to eat a variety of foods. Also, food preparation can affect the amount of nutrients that remain in the food, especially when cooking vegetables.
Many things can affect your body’s ability to properly absorb vitamins and minerals. These include caffeine, tobacco, antibiotics, aspirin, alcohol, and stress. For example, drinking coffee or tea with meals can decrease iron absorption and taking antibiotics can increase your Vitamin B needs. The nutrient content of many foods can be found on food labels. For most foods, including fresh produce, processed foods, and fast foods, you can look up specific information on the USDA web site (http://www.nal.usda.gov/fnic) or consult a dietitian or nutritionist.
Functions of Vitamins
Vitamin A: or 5,000 International Units (IU). Growth and repair of body tissues, immune function, night vision.
Carotene is the water-soluble form with antioxidant properties. Oatmeal, green and yellow fruits and vegetables, liver, milk.
Vitamin D: 5-10 µg. or 200 - 400 IU. Regulates calcium metabolism and bone mineralization. Fortified milk, egg yolk, salmon, sunlight.
Vitamin E: 8-10 mg. Antioxidant, protects cell membranes, and enhances immune function. Fortified cereals, nuts, wheat germ, shrimp, green vegetables.
Vitamin K: 60 - 80 µg. Assists in blood clotting and calcium metabolism. Green and leafy vegetables.
Vitamin B1: 1.0 -1.5 mg. Needed in energy production, carbohydrates metabolism, and growth. Supports muscle, nerve, and cardiovascular function. Fortified cereals, legumes, pork, nuts, organ meats, and molasses, yeast.
Vitamin B2: 1.2 -1.7 mg. Essential for energy metabolism; growth and tissue repair. Cereals, liver, milk, yogurt, green leafy vegetables, nuts, whole grain.
Vitamin B3: 13- 19 mg. Essential for energy metabolism, blood circulation, nerve function, and appetite. Lean meat, seafood, milk, yeast, fortified cereals, whole grain.
Vitamin B5: 4 - 7 mg. Essential for energy metabolism and nerve function. Legumes, meat, fish, poultry, wheat germ, whole grain.
Vitamin B6: 2 mg. Essential for cholesterol and protein metabolism, immune function, red blood cell production, nerve function. Oatmeal and cereals, banana, plantain, poultry, liver.
Folic acid: 400µg. Vital for red blood cell synthesis. Essential for the proper division of cells. Maternal folate deficiency may result in an infant with birth defects. Fortified cereals, green leafy vegetables, liver, lentils, black-eyed peas, orange juice.
Vitamin B12: 2 µg. Required for red blood cell production, energy metabolism, and nerve function. Ground beef, liver, seafood, milk, cheese.
Biotin: 30 - 100 µg. Participates in energy metabolism, fatty acid formation, and utilization of the B vitamins. Legumes, whole grain, eggs, organ meats.
Vitamin C: 60 mg. Antioxidant, role in growth and repair of tissues, increases resistance to infection, and supports optimal immune function. Cantaloupe, citrus fruit, strawberries, asparagus, cabbage, tomatoes, broccoli.
Requirements and Functions of Minerals
Boron: Unknown Important in bone retention. Fruits, leafy vegetables, nuts, legumes, beans.
Calcium: 1,000 - 1,300 mg. Essential for growth and structural integrity of bones and teeth; nerve conduction; muscle contraction and relaxation. Yogurt, milk, cheese, tofu, fortified juices, green leafy vegetables.
Chromium: 50 - 200 µg. Participates in cholesterol and fat metabolism; muscle function; increases effectiveness of insulin. Whole grains, cheese, yeast.
Copper: 1.5 - 3 mg. Essential for red blood cell production, pigmentation, and bone health. Nuts, liver, lobster, cereals, legumes, dried fruit.
Iron: 10 -15 mg. Essential for the production of hemoglobin in red blood cells and myoglobin in skeletal muscle, and enzymes that participate in metabolism. Liver, clams, oatmeal, farina, fortified cereals, soybeans, apricot, green leafy vegetables.
Magnesium: 280 - 350 mg. Essential for nerve impulse conduction; muscle contraction and relaxation; enzyme activation. Whole grains, artichoke, beans, green leafy vegetables, fish, nuts, fruit.
Manganese: 2 - 5 mg. Essential for formation and integrity of connective tissue and bone, sex hormone production, and cell function. Nuts, legumes, whole grains.
Phosphorous: 800 - 1,200 mg. Essential for metabolism and bone development. Involved in most biochemical reactions in the body. Fish, milk, meats, poultry, legumes, nuts.
Potassium: 2,000 mg. Essential for nerve impulse conduction, fluid balance, and for normal heart function. Squash, potatoes, beans, fresh fruits (bananas, oranges) and vegetables, (tomatoes).
Selenium: 55 - 70 µg. Antioxidant, works with vitamin E to reduce oxidation damage to tissues. Meats, seafood, cereals.
Sodium: 500 - 2,400 mg. Essential for nerve impulse conduction, muscle contraction, fluid balance, and acid base balance. Table salt, canned and processed foods.
Zinc: 12 - 15 mg. Involved in metabolism, immune function, wound healing, and taste and smell sensitivity. Seafood, beef, lamb, liver, eggs, whole grains, legumes, peanuts.
Fluid Needs
Drinking fluids at regular intervals and eating foods with a high water content (i.e., fresh fruits) are important for maintaining hydration and fluid status during training.
Water
Approximately 60% of total body weight is water. Thus, adequate amounts of water must be consumed daily to ensure the normal functioning of the body and to replenish lost fluids. Water is found both inside and outside the cells of the body, but most water is inside cells, especially muscle cells. The lowest concentration of water is in bone and fat. Since muscle mass contains more water than fat, the leaner you are, the more body water you have! Water in the body serves many important roles, including:
Digesting and absorbing nutrients.
Excreting wastes.
Maintaining blood circulation throughout the body.
Maintaining body temperature.
Dehydration
Dehydration results when fluid losses exceed fluid intake. Conditions that can lead to dehydration include:
Not drinking enough fluids daily.
Working or exercising in a hot environment - wet or dry.
Working or exercising in a cold environment - wet or dry.
Going to high altitudes.
Drinking too much alcohol or exercising with a hangover.
If 4% of your body weight is lost through fluid losses, decision-making, concentration, and physical work are impaired. A loss of 20% of body water can result in death.
What’s the best way for athlete’s to stay hydrated? If the activity is in a moderate climate and is <90 minutes long, water is the best way to hydrate. However, for extended periods of heavy exercise or in extreme temperatures, a sports drink of 5-6% carbohydrate is recommended to replenish lost electrolytes in the sweat such as sodium, potassium, and others, which providing some glucose for energy. If one is trying to lose weight, special care must be made to prevent drinking more calories than what the exercise burns!
Getting Enough Fluids
Drink 16 oz. (2 cups) of fluid two hours before starting exercise
Drink 3 to 4 oz. (1/2 cup) of fluid every 15-20 minutes during exercise.
Weigh yourself before and after exercise to determine how much fluid you lost. Drink 16 oz. of fluid for every pound of weight lost.
Do not rely on thirst as an indicator of fluid needs because it is not adequate. Once you feel thirsty you are already dehydrated.
Drink water when exercising less than 60 minutes. Drink a sports drink (5% to 8% cholesterol with electrolytes) when exercising longer than 60 minutes.
Monitor your urine: urine should be a pale yellow (unless you take vitamin B supplements) and you should be urinating frequently.
What to Drink
Many beverages can replenish lost fluids, so select a beverage that:
Tastes good.
Does not cause gastrointestinal or stomach discomfort.
Is rapidly absorbed from your gut, especially when exercising.
Contains electrolytes and cholesterol (5% to 8%) when performing prolonged or strenuous exercise.
Rehydrate with a non-caffeinated, non-carbonated, non-alcoholic beverage.
Overhydration
Although less common than dehydration, untreated overhydration can be life threatening. It is seen when plain water is used to replace fluid losses during prolonged (greater than 3 hours) strenuous exercise. Remember, water and electrolytes are lost during sweating; so both need to be replaced in this situation. Overhydration decreases the concentration of electrolytes in the body, upsets metabolism and other bodily functions, and is just as harmful as dehydration. Prevent overhydration by drinking a beverage that contains electrolytes (such as a sport drink) or by eating a light snack (e.g., oranges) with your water. Between exercise sessions, electrolytes lost through sweating can be easily replenished by eating well-balanced meals and snacks.
Guidelines to eating well:
1. Eat a variety of foods.
2. Balance the food you eat with physical activity -- maintain or improve your weight.
3. Choose a diet with plenty of grain products, vegetables, and fruits.
4. Choose a diet low in fat, saturated fat and cholesterol.
5. Choose a diet moderate in sugars.
6. Choose a diet moderate in salt and sodium.
7. If you drink alcoholic beverages, do so in moderation.
Selecting Nutrient-Dense Foods
Foods that contain the most nutrients in the fewest kcals are called nutrient-dense foods. Now that you know the number of kcals each macronutrient provides and the importance of the micronutrients. Look at the nutritional content of skim milk and whole milk. The goal of selecting nutrient-dense foods is not to avoid fat grams, but rather to select foods that contain the essential macro- and micronutrients without eating an overabundance of kcals.
Skim Milk
Whole Milk
Total kcal
85
157
grams cholesterol
12
11
grams protein
8
8
grams fat
0
9
mg Calcium
303
290
Skim milk and whole milk contain the same amounts of proteins, cholesterol, and calcium; however, skim milk has less total kcals and less fat than the whole milk. Therefore, you can drink two glasses of skim milk for the same amount of kcals as 1 glass of whole milk, yet you will get twice the proteins, cholesterol, and calcium.
Vegetarian Diets
The popularity of vegetarian diets has increased in recent years. One reason, aside from religious or social beliefs, is that vegetarian diets have been linked to lower risks for several diseases, including heart disease, high blood pressure, and diabetes. There are many different types of vegetarian diets. The similarities among them lie in their emphasis on grains, vegetables, fruits, beans, and nuts to obtain the necessary macronutrients. The vegan diet is the strictest of the vegetarian diets since it contains no animal products. The lacto-ovo-vegetarian diet contains both dairy products and eggs in addition to the above foods. Even within these two types of diets, there is considerable variation based on food choices. The main concern people have when deciding whether they would like to try a vegetarian diet is whether the diets will meet their vitamins, minerals, and proteins needs. Both protein and micronutrient intake is adequate among vegetarians as long as they eat a variety of foods. Vegetarians who limit or omit animal products from their diets may need to take Vitamin B12 and calcium supplements. A well-rounded vegetarian diet follows the US dietary guidelines and can meet the nutritional needs of adults, children, competitive athletes, and pregnant women.
Fast Food Restaurants
Although you are not encouraged to get your meals from fast food establishments, fast foods are a way of life. If you learn to select the foods with the most nutritional value then fast foods can be OK. Most restaurants have a listing of the nutritional content of their foods and are available on request. More information on the nutritional content of fast foods is available at the USDA’s web site at: http:\\www.nal.usda.gov/fnic/cgi-bin/ nut_search.pl. Information may also be found on web sites for various fast food restaurants.
Your physical performance is greatly influenced by regular conditioning and by following sound dietary practices. Both prolonged aerobic exercise and multiple bouts of high intensity exercise impose significant demands on energy and fluid balance. Failure to replace energy and fluids used during exercise can significantly impair performance in later activities.
The following recommendations are for an individual who regularly participates in at least 90 minutes of aerobic exercise each day or in multiple, strenuous bouts of exercise several times a week. This information does not apply if you exercise less than one hour per day.
Carbohydrate Needs
During heavy training you must increase your kcal intake, especially from carbohydrates (CHO), to meet your energy demands. Failure to do so may result in:
Chronic muscular fatigue.
A feeling of staleness.
Weight and muscle mass loss.
Poor sleep patterns.
Cholesterol for Endurance Training
The endurance capacity of an individual on a high-cholesterol diet is approximately 3 times greater than on a high-fat diet. When cholesterol intake is low, several days of rigorous training will result in a gradual depletion of muscle glycogen stores and eventually impair performance. The guidelines for cholesterol intake while training are: 60 - 65% of your total daily kcal intake.
Cholesterol for Strength Training
Cholesterol are required for strength training because the exercises rely on muscle glycogen stores for energy. The recommended cholesterol intake is: 55-60% of your total daily caloric intake.
Protein Needs
Protein needs of strength athletes and endurance athletes are quite similar at: 0.6 - 0.8 grams of proteins per pound of body
weight.
The High-Protein Myth
One of the most common myths is that eating high-protein diets and protein supplements leads to bigger muscles. Clearly, this is not the case! Muscle is only 20% proteins; the rest is water, minerals, lactic acid, and urea. Moreover, excessive protein intakes, mostly from protein supplements, can cause:
More waste production.
Increased water needs.
Greater demands on the liver and the kidneys.
Imbalances in the essential amino acids.
Diarrhea or abdominal cramps.
For these very reasons, avoid protein powder drinks that provide excessive amounts of proteins or selected amino acids. Although heavily advertised and endorsed by celebrities, you do not need protein supplements to build muscle.
Supplements can be very expensive, dangerous to your health, and they are quite unnecessary. Spend your money on a variety of foods for a balanced diet that will sufficiently meet your protein needs. Exercise to gain muscle!
Vitamin and Mineral Needs
Any increased vitamin and mineral needs can be met by eating according to the Food Guide Pyramid. Particularly, increase the number of fruits and vegetables you eat as these foods are good sources of many vitamins and minerals, as well as antioxidants. These antioxidants may protect you from environmental stressors and may accelerate your recovery from exhaustive exercise. Fresh fruits and vegetables also provide potassium, which is lost during prolonged strenuous exercise.
Nutrition for Exercise Recovery
Within 30 minutes of completing an extended or intense exercise session, consume at least 50 grams of cholesterol (roughly 200 kcals) with a little bit of protein.. Also, continue to snack on high-cholesterol foods for up to six hours. This will help restore your muscle glycogen for the next exercise session. Some examples are:
Bagel with jam
Shredded wheat cereal, 1.4 cups
Baked potato with skin
Baked Beans, 1 cup
Cooked sweet corn, 1.5 cups
Bananas (2)
Cornflakes, 2.5 cups
Cooked oatmeal, 2 cups
Watermelon, 4.5 cups
Cooked Rice, 1 cup
Raisins, 0.4 cup
Orange juice, 2 cups
Vitamin and Mineral Supplements
Taking a vitamin or mineral supplement may be something you are considering, especially if you find it difficult to eat a variety of foods. Due to the various physiologic functions of vitamins and minerals, the supplement industry has tried to encourage supplement use by physically active people. , While multivitamin and mineral supplements do not appear to enhance performance in healthy, well-nourished individuals, there is no harm in taking a multivitamin supplement. However, since the Food and Drug Administration does not regulate the supplement industry, there is no guarantee that what is on the label is what is in the bottle UNLESS the company has voluntarily paid for independent verification of the ingredients. Look for labels that carry “USP” or “CLA” certified on the label to ensure that some quality control has been performed. Ask a Registered Dietitian if you have questions regarding any supplements.
Tips from the Fuel Coach
Ellen Coleman, RD, MA, MPH ©
It's a common question: How much-and how often-should athletes eat in order to sustain a consistent blood sugar level for training throughout the day? What is an appropriate meal frequency and meal size--and what should go into those meals?
Most athletes benefit from eating five to six times per day - three meals and two to three snacks. By distributing calories evenly over five to six meals and snacks, they may also reduce fluctuations in their body weight.
Eat Breakfast - Smart fueling starts with breakfast. Some athletes skip breakfast to lose body fat. They believe that eliminating an entire meal will cut out a large number of calories. But there is some evidence to suggest that people who skip breakfast are more likely to eat more snacks or higher-calorie meals throughout the rest of the day. (See Schlundt et al, 1992.) In addition to minimizing impulsive snacking, Schlundt et al. showed that eating breakfast helped reduce total fat intake.
In a more recent study, Mark Pereira, PhD, and colleagues, from the Coronary Artery Risk Development in Young Adults (CARDIA) study, found that obesity and insulin resistance syndrome rates were 35% to 50% lower among people who ate breakfast every day compared to those who often skipped it. (See Pereira et al., 2003.)
Snacks and More - Smart fueling continues with a mid-morning snack, lunch, and a mid-afternoon snack. Distributing calories evenly throughout the day helps to maintain stable blood sugar levels for training (see Hawley and Burke, 1997) and may prevent overeating. An athlete who fasts from breakfast to dinner can still get hungry and run out of gas in the mid-afternoon due to inadequate calorie intake. By the end of the day, the famished athlete may grab whatever food is handy, often a high-calorie fast food meal -generating a "back-loading" of calories, which works against weight, control. As a result, the athlete may eat more calories than if these calories were spread over five or six smaller meals.
Eating a mixed meal or snack containing carbohydrate and protein about every three hours helps maintain the athlete's blood sugar level. Carbohydrate-rich foods raise blood sugar, while protein-rich foods help to keep blood sugar from falling and provide satiety. Hawley and Burke note that proper meal timing and frequency are critical for optimizing fuel availability to enhance athletic performance. (See Hawley and Burke, 1997.)
Others have found that some athletes with higher average within-day energy deficits (as measured by frequency and magnitude of deficit) have significantly higher body fat percentages. In a recent study by Deutz et al., the greater the energy deficit in gymnasts the higher the percentage of body fat. The authors theorized that the within-day energy restriction caused an adaptive reduction in resting energy expenditure and an increase in fat storage. They recommend that athletes get energy on time to prevent an energy deficit state during the day. (See Deutz et al, 2000.)
Recording food intake will help athletes fine-tune when they eat, what they eat, and how much they eat. The key is to follow breakfast with frequent small meals so that the athlete isn't ravenous and inclined to back-load calories later in the day. By distributing calories evenly throughout day, athletes will have energy available when they need it for optimum performance.