SPORTS MEDICINE
February 22, 2011

Extreme Nutrition

Lona Sandon, M.Ed., R.D.
Elite athletes can teach us all a lot about eating right. Who knew chocolate milk was the perfect recovery drink?
Ms. Sandon is Assistant Professor, UT Southwestern Medical Center, Dallas, TX.

Good nutrition is important not only in weight loss and maintaining healthy weight, it is key to our overall health and longevity and plays a major role in the prevention of diseases and other health issues down the road. Professional athletes and those who exercise hard regularly need to make smart food – and fluid – choices. So it makes sense that some of the lessons they have learned about how to eat and basic nutritional strategies they employ to maintain energy and fitness might be very useful to the rest of us.

While most people do not need to devote the kind of attention serious athletes do to the content and timing of their food and drink choices, understanding why these choices work well for the body and loosely modeling our own routines after them can be beneficial.

For example, after a workout, choosing the right foods can make a big difference in how our bodies "recover" from exercise. In this article, we will talk about the current guidelines for sports nutrition, which applies both to serious athletes and to the rest of us who engage in regular (or even irregular) exercise routines. We’ll also look at a case study of Anna, an amateur athlete. Though her exercise routine may be more ambitious than most, it’s still helpful to take her as an example to understand how to best fuel the body before, during, and after physical activity.

What Can an Endurance Athlete Teach "Regular" People about Good Nutrition?

Anna, is 37 years old, 5’ 5", and weighs 135 pounds. She works in a human resources department and spends most of her day at a desk. However, she is also an endurance runner and tri-athlete. She runs, swims or bikes for one hour before work four times per week. On Saturdays she does four to five hours of combined running and biking starting at 8:00 AM.

Anna gives a lot of thought to what she eats and drinks. Not only does she make sure to eat enough calories to support her impressive exercise routine, but she pays special attention to the proportion of carbs, protein, and fats she consumes. Even more, she makes sure to eat at specific times before, during, and after exercising to allow the body to absorb its fuel in the best way possible.

While most people do not need to devote the kind of attention Anna and other serious athletes do to the content and timing of their food and drink choices, understanding why these choices work well for the body and loosely modeling our own routines after them can be beneficial. The major issues of good nutrition are basically the same; it is just a matter of degree.

How Many Calories Do We Actually Need to Consume?

For everyone – serious athletes and regular folk alike – it’s important to consume enough calories to meet our energy needs. Doing so not only makes exercise and recovery from exercise possible, but it actually helps prevent injury and illness. Getting enough calories helps preserve muscle tissue, bone density, and reproductive function – a particular concern in high performing female athletes. It also helps direct protein to building muscles, rather than being used as energy.

It's worth noting that a registered dietician is not a nutritionist. Anyone can call him- or her-self a nutritionist.

Active adults feel weak and fatigued if they don’t consume enough calories, whether they are athletes training for competition or not. Other nutritional requirements, such as essential vitamins and minerals, also tend to be unmet when people do not eat enough1, which is why it is so important to consume a balanced diet.

A person’s specific energy requirement can be determined by crunching some numbers and taking into account his or her age, height, weight, gender, and activity level. While experts use a couple of different formulas for determining a person’s energy needs (the DRI Estimated Energy Requirement (EER) and the Cunningham equation), we won’t go into the mathematics behind the equations. But just know that it varies greatly from person to person, depending on all the variables mentioned above.

Our athlete Anna’s average daily requirement is calculated to be 2935 calories across seven days. This means that if she eats 2800 calories one day and 3070 another day, she’ll be okay. The same is generally true for the rest of us – if we eat a little too much one day, we don’t have to eat as much the next day – although we may not always live by this scientific reality! Most active men need about 2600 calories a day, and women need 2000 calories, but again, it varies from person to person depending on many factors. If you are having a difficult time determining your specific energy requirements, it’s a good idea to see a registered dietitian for help.

It's worth noting that a registered dietician is not a nutritionist. Anyone can call him- or her-self a nutritionist. A registered dietitian has a minimum of a bachelor degree in nutrition, 900 hours of internship, and has passed a national registration examination similar to the boards that nurses and doctors must pass to practice.

How Do We Determine What's a Good Body Weight?

Many people are familiar with the body mass index (BMI) for calculating how much fat makes up a person’s body. But this calculation doesn’t always work for all body types. The BMI can actually be a little misleading for people who are muscular as well as for people who have very little muscle mass. So, a professional athlete like Anna would have a relatively high BMI, indicating that she’s overweight or even obese, even though her body is actually made up for very little fat. For this reason it’s also important to think about your body composition, in addition to other measures like waist circumference and hip-to-waist ratio when trying to come up with your ideal weight. Using more than one measure leads to a more accurate picture of a person’s overall makeup.

How Much Body Fat Is Healthy?
Body composition varies greatly from person to person, since we all have different body types and different activity levels, depending on our professions and leisure time activities. But for all of us, some body fat is necessary for our best health, physically and mentally.

Women who have very little body fat, especially female athletes, may suffer from low estrogen levels, amenorrhea (lack of menstrual periods), and osteoporosis, known as the Female Athlete Triad (FAT).

Experts say that the minimum amount of body fat for a healthy woman is 12%. For men it’s 5%. Healthy body fat ranges are listed in Table 1. It is important to realize that for both athletes and for active adults, restricting calories and over-exercising to achieve a low level of body fat is not healthy. It is very possible to be too thin for good health and being so can inhibit physical activity, and compromise important body processes.

Body fat is a key source of energy during exercise and it also serves other functions, like protecting our organs and producing sex hormones. Women who have very little body fat, especially female athletes, may suffer from low estrogen levels, amenorrhea (lack of menstrual periods), and osteoporosis, known as the Female Athlete Triad (FAT). So, despite the Hollywood ideal these days, being too thin can pose significant risks to our health and longevity.

Table 1
Healthy Body Fat Ranges For Physically Active Adults
__% Body Fat___________
Age Women Men
Under 55 16% to 28% 5% to 15%
Over 55 20% to 33% 7% to 8%

In Anna’s case, her height and weight give her a BMI of 22.5 which is well within a normal weight classification. Also her 23% body fat places her in the middle of the range for healthy body fat for physically active adults. She should be encouraged to continue to maintain her current weight and body composition.

Eating for Exercise: Choosing Calorie Sources to Support Our Needs

The type of calories an active adult needs is determined by his or her activity level and the specific types of exercise he or she engages in. Most people can take in enough calories and nutrients by following the standard recommendations for their activity levels.

People who are serious athletes use calories at a far higher rate than most of the rest of us. They mainly rely on a mixture of fat and carbohydrate stores to produce energy. As an endurance athlete, Anna relies mostly an aerobic energy production system that primarily uses muscle glycogen, the carbohydrate energy stored in the muscle, and fatty acids to fuel endurance activity.

Weight lifters who skimp on carbs and eat loads of protein (steak, tuna, chicken breast, egg whites) actually end up using their protein as an energy source instead of using it to build muscle. Protein is converted to carbohydrate when carbohydrate stores are low.

The specific energy system an athlete uses depends on the type of activity they do. Weight lifters and sprinters rely on the same energy production system — anaerobic, and their proportions of carbohydrates, protein and fat should be about the same.

Weight lifters tend to mistakenly over-consume protein and under-consume carbs. Weight lifting and sprinting rely on anaerobic energy production, meaning they need a quick, short burst of energy that, unlike the endurance athlete, doesn't rely on oxygen (aerobic). People needing this quick energy can only use carbohydrate as an energy source, and so they need to have fruit, whole grains, starchy vegetables like potatoes and beans to build up carbohydrate stores in the muscle to fuel their workouts. Weight lifters who skimp on carbs and eat loads of protein (steak, tuna, chicken breast, egg whites) actually end up using their protein as an energy source instead of using it to build muscle. Protein is converted to carbohydrate when carbohydrate stores are low.

How Much Carbohydrate Should We Eat?
Most people know about the importance of eating healthy carbs for energy during exercise (just think about stories of marathoners enjoying pasta dinners the night before the big race). During exercise, glucose (broken down from glycogen) and energy from fat provides most of our energy. When we’re working out at moderate capacity, our energy comes equally from fat and carbohydrates; at higher intensities, carbohydrates take over. But when we exercise for longer time periods, even at lower intensities, carbohydrates are essential.

The timing and size of carbohydrate-rich meals are important factors in how we perform during exercise. Some studies have found that consuming a meal rich in carbohydrates a few hours before exercise is a good idea. The closer to exercise the meal is consumed, fewer carbs and smaller meals will help prevent gastrointestinal problems. A pre-exercise snack may be helpful if it has been more than four hours since the last meal. At these times, it is best to eat easily digestible foods such as fruit or 100% fruit juice, graham crackers, granola bar or sports bar such as a Power Bar or Cliff Bar, low in fat and fiber.

Some people use amino acid or powdered protein supplements, but these have not been shown to be more effective than getting protein from quality food sources.

Some people prefer liquid meals such as Boost, Carnation Instant Breakfast or a glass of flavored milk before exercise, since they are a quick fix, and easy to digest. A liquid meal also boosts fluid intake, which is an important factor in exercise (more on this later). Consuming sports drinks during extended exercise – more than 60 to 90 minutes – can replenish lost fluids, electrolytes (like sodium and potassium), and carbohydrate. However, sometimes it’s difficult to get all the carbs one needs from sports drinks, so other foods like sports bars, salty snack crackers, gels, or gummies can be useful.

You may want to play around with different combinations of foods and drinks in and around exercise to see what works best for you under different circumstances. An athlete like Anna would want to eat 65 to 70 grams of carbs 4 hours before or at most regular mealtimes, and 30 to 45 grams of carbs after her training sessions.

How Much Protein Do We Need?
Certain types of training increase one’s protein needs above the recommended intake – for instance, endurance and resistance training1. But for all people, the number of total calories and the amount of carbohydrate you eat have an influence on the amount of protein you need to consume. Eating enough calories and carbs is important in making sure that protein gets used for making muscle and playing a part in normal body functions. In addition, people who restrict calories, are vegetarians, eat low-carb diets, or exercise vigorously on consecutive days need to take in extra protein. However, eating more than 1 gram per pound of body weight has not been shown to have any benefit. See Table 2 to determine your daily protein needs.



Table 2
Recommended Protein Intake
Training condition Recommendations in grams/lb/day
Sedentary adult 0.4 g
Recreational exerciser - adult 0.5 – 0.75 g
Growing teenage athlete 0.9 – 1.0 g
Endurance athlete - adult 0.6 – 0.7 g
Strength athlete - adult 0.8 – 0.85 g
Immediately before strength training 7 - 10 g
Immediately after strength training 7 – 10 g

Eating protein before and after exercise helps the body make new muscle tissue and repair the muscles that are strained during exercise. High-quality protein that contains the essential amino acids is better than protein that contains non-essential amino acids (essential ones are those we need in the diet because the body cannot synthesize them on its own). Though there has been some debate, eating protein during exercise does not seem to boost performance at all.

Most active people and athletes get enough protein due to their higher overall calorie intake, so they do not need to supplement. If you are very active, a doctor or registered dietitian might need to do a thorough dietary analysis before determining whether you need a protein supplement. Some people use amino acid or powdered protein supplements, but these have not been shown to be more effective than getting protein from quality food sources. As far as non-meat protein sources, milk-based proteins (like whey and casein) appear to be more beneficial than soy-based protein. Whey protein is absorbed more quickly into the blood stream, and is a good source of the amino acid leucine, which plays a central role in new muscle formation.

Again, it’s a good idea to talk to your doctor or registered dietitian before adding a protein supplement to your diet. Too much protein can lead to dehydration, but other than this there do not appear to be major health risks from high levels of protein other than not getting the nutrients you need from other types of foods when too much emphasis is placed on protein.

How Much Fat Is Healthy?
Like proteins and carbs, the amount of fat a person needs in his or her in the diet varies depending on a number of factors, like age, sex, and lifestyle — including one’s job and the amount of physical activity he or she engages in during leisure time. In general, it’s recommended that adults consume 20–35% of their calories from fat. What is important is to make smart choices when it comes to fats, opting for the healthy fats such as poly- and monounsaturated fats rather than saturated and trans fats.

Dietary fat should not be restricted too much, as it is crucial for good health, particularly among people who are very active. Fats are an excellent source of energy, especially during exercise, and they also provide important building blocks for tissues in the body and brain. They are also crucial for the absorption of fat-soluble vitamins and take part in a number of body processes. The good fats like mono- and polyunsaturated fatty acids also help keep our cholesterol levels in check. Very low fat diets often mean that a person is not consuming enough calories overall, and have also been linked to nutrient deficiencies and hormone dysfunction, like low estrogen levels.

Stay Fluid: Drinking Enough

In addition to the carbohydrates, proteins and fats we eat, drinking enough fluids is essential to our health, whether we’re athletes or not. Many of us grew up hearing the recommendation "8 x 8", indicating that eight 8-ounce glasses of water per day was the ideal. However, experts now recommend that men drink 16 cups per day and women drink 12 cups per day. Active adults and athletes may need to drink even more than this to make up for fluid lost in sweat.

Luckily, one’s daily fluid intake can be met from a variety of sources including water, milk, 100% fruit juice, coffee, tea, soup, sports drinks and even fruits and vegetables that have high water content. Drinking caffeinated beverages within reason, less than 3 cups of coffee or caffeinated drinks per day, does not seem to have a great effect on dehydration. Alcohol, however, can make you urinate more (which can dehydrate you). For this reason, it is not advised to consume alcohol after exercise when rehydration is important, despite what the beer-drinking weekend warriors in so many advertisements seem to suggest.

Many studies have shown that milk significantly increases muscle mass and decreases muscle damage when consumed after exercise. Some studies have shown that low-fat milk and low-fat milk with added salt both helped serious athletes replenish fluids better than sports drinks and water.

Because exercise can deplete your body of fluid very quickly, it is important to have a good routine for replacing your fluids after exercise. Losing as little as 2% of one’s body weight in fluid (as can happen with 60 minutes doing endurance sports (cycling, running swimming, roller blading) can cause significant problems in both physical and mental performance.

Dehydration can cause increased heart rate and body temperature, and it can make one feel much more tired than he or she would actually be in a non-dehydrated state. Like food, fluid requirements depend on many factors, like gender, body weight, temperature, humidity, and the duration and intensity of exercise. Women tend to have less sweat and electrolyte losses than men but are at greater risk of becoming sodium deficient (known as hyponatremia).

What to drink depends largely on the type of exercise one is doing and the climate, as well as individual preferences. Plain water is will usually do the trick for exercise lasting less than 90 minutes in controlled temperature environments. Sports drinks are better for extended exercise duration, hot humid climates, high sweat rates and "salt losers" (people who lose more salt than the average), and for those who don’t like the plain taste of water. Sports drinks are a good choice since they replace carbohydrates, fluid, and electrolytes lost in sweat. Serious athletes, those who sweat heavily, and high "salt losers" may need to add additional salt or choose higher salt-containing endurance formulas.

Don't confuse recovery drinks with sports drinks like Gatorade, PowerAde, Propel, or Accelerade.

The American College of Sports Medicine (ACSM) recommends that people consume 2 to 3 cups of liquid a few hours before exercise. This allows the body to absorb the fluids and produce urine before exercising. Having drinks with meals and choosing beverages with a small amount of sodium (such as milk), and eating foods with sodium, can help the body retain fluid better.

During extended periods of exercise, it is, of course, important to consume fluids before symptoms of dehydration set in. For people who engage in strenuous exercise, experts recommend drinking 2-3 cups of fluid for every pound lost during exercise. Your urine should be just very pale yellow, nearly clear. If it's not, you need to drink more.

Table 3
General Fluid Recommendations
Before exercise Drink fluids with meals
2 cups - 2 hours before exercise
1-2 cups - 15 minutes before exercise
During exercise Roughly 1 cup every 15 - 20 minutes
After exercise 3 cups per pound of body weight lost during exercise
2-3 cups or enough that urine is a pale yellow color


Eating After Exercise

Eating after exercise is important for a number of reasons. It helps you replenish lost fluids and energy stores, and gives your muscles the essential amino acids they need to repair themselves. For serious athletes who are training on consecutive days, the timing of the post-exercise meal is important. Consuming carbohydrates within 30 minutes of training is suggested. For the rest of us, the timing of eating is not so critical, but it’s still important that we eat after activity to help our bodies repair and reboot. In addition to carbs, eating protein after exercising also helps the body replenish protein and aids in the repair of the large muscles of the body.

Chocolate Milk: The Wonder "Food"
You may be happy to hear that low-fat chocolate milk is considered by experts to be quite a good post-exercise recovery drink – and its use as such has actually been studied scientifically. It provides about the same amount of carbohydrates as those found in recovery drinks (such as Muscle Milk, Boost or even Slim Fast) as well as essential amino acids. (Don't confuse recovery drinks with sports drinks like Gatorade, PowerAde, Propel, or Accelerade.)

Chocolate milk is also a natural source of sodium and potassium, the main electrolytes lost in sweat. Many studies have shown that milk significantly increases muscle mass and decreases muscle damage when consumed after exercise. Some studies have shown that low-fat milk and low-fat milk with added salt both helped serious athletes replenish fluids better than sports drinks and water. Milk also provides calcium and vitamins B12 and D, which also helps one meet his or her nutritional needs after exercising. For all of these reasons, low-fat milk (or chocolate milk, if one so chooses) may be a good alternative to sports drinks after exercise.

To Supplement or Not To Supplement? That is the Question

Moderate and intense exercise may increase the need for certain vitamins and minerals, but does this mean you need to take supplements? Generally not, except under special circumstances. Because athletes usually have higher calorie intake, their need for extra vitamins and minerals is usually met by the additional food they eat. Very active people who restrict calories, are vegan, or follow otherwise restrictive diets, however, could be at risk for deficiencies and may want to supplement.

It is important to point out that vitamin and mineral supplementation have not been shown to improve physical performance when adequate calorie and nutrient requirements have been met through the diet.

For serious athletes who are training on consecutive days, the timing of the post-exercise meal is important. Consuming carbohydrates within 30 minutes of training is suggested.

The vitamins and minerals most important for the athlete’s body are the same as for the rest of us: calcium, vitamin D, B vitamins, iron, zinc, and magnesium. Low calcium and vitamin D intakes may put a person at risk of stress fractures, low bone mineral density, and muscle pain. Too little iron intake affects the body’s ability to circulate oxygen effectively, which impacts physical activity and endurance. Zinc deficiency can affect muscle strength and endurance, immune system and proper functioning of the heart and lungs. Low magnesium can take a toll on one’s endurance. All of these nutrients can be obtained in adequate amounts through a balanced diet rich in fruits, vegetables, whole grains, nuts and seeds, low fat dairy and lean protein sources.

In general, eating nutrient-rich foods is a much better way to go than taking supplements, since vitamins and minerals are absorbed better when they’re taken in through the diet. While some athletes believe that antioxidants like vitamin C and E may help the body recover from the damaging free radicals produced during exercise and decrease muscle damage, there’s not much evidence that antioxidant supplementation is necessary. Routine training actually increases the body’s ability to deal with free radicals.

Some who are very athletic may choose to supplement vitamins C and E for various reasons, no one should go past the tolerable upper limit for any vitamin or mineral, since doing so can pose serious health risks.

The Takeaway: Eat, Drink and Be Active

For endurance athletes like Anna and the rest of us, good nutrition helps prepare the body for optimal performance during exercise. It’s important to keep an eye on protein, carbohydrate, and fat consumption, eating these foods in adequate amounts to support our energy needs, depending on our lifestyles and the activities we choose. If what we eat doesn't adequately supply our bodies with the nutrients they need, we can experience fatigue, weight gain or weight loss or fail to build muscle the way we'd like.

Carbohydrates help prevent fatigue during exercise and in helping the body recover from it afterwards. Getting enough calories and carbohydrates allows protein to be used for other things besides energy, like repairing muscles and taking part in other important body functions. Though serious athletes may need more protein than other people, there does not seem to be a benefit in consuming more than 1g/lb in protein; 0.5g/lb is enough for most.

Drinking enough is also important to performance. Not only do we need to replace the fluids lost during exercise, but we need to replace the electrolytes lost in sweat. Drinking sports drinks for rehydration during and after exercise lasting more than 60 minutes, especially when one is exercising in hot humid conditions.

Most people, including serious athletes, do not generally need additional vitamins and minerals beyond what they get in a healthy, varied diet. It is better to consume your nutrients in foods, which helps absorption, rather than taking supplements. If you have additional questions or concerns about your diet, nutrient, or vitamin and mineral consumption, the resources below may help answer your questions. Depending on your activity level and specific dietary restrictions, talking to a Registered Dietitian or to your doctor about your concerns may also be a good idea.

Sports Nutrition Web Resources

American Dietetic Association, Dietitians of Canada, and American College of Sports Medicine – Nutrition and Athletic Performance
http://www.eatright.org/About/Content.aspx?id=8365

Australian Institute of Sport – Nutrition
http://www.ausport.gov.au/ais/nutrition

Sports, Cardiovascular, and Wellness Nutrition Dietetics Practice Group – Sports Nutrition Fact Sheets
http://www.scandpg.org/sports-nutrition/sports-nutrition-fact-sheets/

Sports Dietitians Australia – Fact Sheets
http://www.sportsdietitians.com.au/factsheets/

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