Food for Thought: Eating Disorders Awareness
“Knowing Your Body: Eating, Exercising and
Physical Health”
Susan Fullmer
The following is a transcript is a presentation given at
I’m delighted to be here today and talk about knowing your body, eating, exercise, and bone health. When we talk about bones, our primary concern, the largest disease that we struggle with is osteoporosis. Osteo means bone and porosis means porous, and so literally we are talking about porous bone. Osteoporosis by definition is a disease that’s characterized by a low bone mass and poor micro-architecture leading to fractures primarily in the hip, the spine, and the wrist. So we’re talking about two things. We’re talking about a low bone mass, a small skeleton or a thin skeleton as well as a micro-architecture – the structure of the calcium and phosphorus, the lattice network that forms inside of our bones – that puts us at risk for fractures.
Osteoporosis is a major health problem in the
Let’s just do a little bit of anatomy and physiology of a bone to help us understand more about osteoporosis. There are two types of bone. There is cortical bone, which is the hard outer shell, or the covering of the bone, and it predominates in the long shafts of our bones – in our arms, in our legs, it’s in our hands and our feet. This type of bone, cortical bone, is very strong, and it makes our bones very resistant to fracture. It’s very stiff and it’s the most common type of bone that we have. It constitutes 75 percent of our skeleton. But the other type of bone is called trabecular bone, and it’s soft and spongy. It’s this bone that’s on the inside, and it’s very spongy and very porous. Trabecular bone forms the internal network of our bone. It’s not as strong as cortical bone. In a lot of ways, it has different functions – it’s provides shock absorption, for example, for our bones.
Let’s consider a 31-year-old female’s bone compared to an 81-year-old female’s bone. The 31-year-old’s bone has a very well developed lattice network, but the 81-year-old’s bone has big holes. So, this shows well-developed architecture and then poorly developed architecture. This is primarily affecting the trabecular bone, and osteoporosis for postmenopausal women tends to affect the micro-architecture, the trabecular bone. But as we get older, it (osteoporosis) affects both the cortical as well as the trabecular bone, and later when we talk about anorexia, anorexia can affect both of them, too, even though a person is very young. So a little bit more about bone physiology, bones are always under construction, and the term we use is “remodeling”. Bones are always being remodeled. Once we build our skeleton, we don’t keep that calcium forever. Little bits of bone are constantly being broken down, digested literally, and replaced with new bone – as we grow and even in adulthood, we’re always breaking our skeleton down and rebuilding it, so it’s always being remodeled. Infants replace their entire skeleton in the first year of life, and as we reach adulthood, that slows down quite a bit and we replace it about 18 percent per year, meaning about every five to six years we replace our skeleton.
Right away, I hope we realize that calcium intake is always important throughout the lifespan to maintain healthy bone. When we are putting calcium into our bones, calcium and other minerals, we call that bone deposition. When we pull calcium out of our bones and return it to the bloodstream, we call that bone resorption. As we are growing, bone deposition, mineral deposition exceeds resorption, and hence our skeleton gets bigger in terms of total height as well as diameter. It gets more dense, more calcium is put in, and so deposition is exceeding resorption. When we reach adulthood, we maintain that bone density – and hopefully we maintain it – and that would happen if bone deposition and resorption were the same. But later in life – not as late as you think, in our late thirties or early forties – we begin to have a negative calcium balance in our bones where we lose more than what we rebuild. So gradually we begin to lose bone density.
There is a huge gain in bone density up to our late teens, early twenties. And then we gain a little bit more, but then we hit what’s called a peak bone mass – this is the maximum amount of bone density that we’ll ever attain – and when attain that, well, it’s controversial when it’s attained. Some people say it’s attained in late teens, some say, “Well, it’s early twenties,” some say clear up to age 30 we continue to gain bone density – I don’t think it’s really clear when that actually happens. But at some point in time, we do reach a peak bone mass and then we maintain that for a couple of decades hopefully at least, but as you can see in this graph, in our late thirties, early forties, we gradually begin to lose some bone. And at some point, we put ourselves at risk of a fracture. However, there is not a bone mineral density that I can give you, a number and say, “When you hit this point, you’re going to be at risk of fractures,” because other things come into play that put us at risk for a fracture. But at some point, we do have such a loss of bone mass that we are at an increased risk of fracture.
It’s also important to note that we can gain a large peak bone mass and be well above this fracture risk, and so when we start to lose bone when we get older, it’s going to take a long time before we cross that threshold and find ourselves at risk of fracture. By the same token, however, there’s some circumstances beyond our control, circumstances within our control, behaviors we engage in, that cause us to only gain a small peak bone mass, and so we never get up very high, so we’re just barely above this fracture risk range. It doesn’t take a lot of bone loss before we’re at risk for fractures and the consequences of osteoporosis.
In terms of osteoporosis, our primary concern is a risk of fractures. There are three things that put us at risk of fractures. The first is a propensity to fall; the second is having a low bone density or low bone mass, what we’ve been talking about; and the third is a poor bone quality, where the micro-architecture is not complete. Well, as young adults, we’re not at a propensity to fall generally and our bone quality is assumed to be good. I don’t know how much has been looked at in terms of bone quality in young adults, but bone quality probably is good, certainly better than it is as we get older. But our risk is potentially a low bone mass or bone density. And what things cause a low bone density? Well, there are two: number one is reaching a low peak bone mass, never getting a lot of bone mass in the first place, and the other one is to have increased losses during adulthood. That happens naturally as we age; it happens when women go through menopause and stop having menstrual cycles – estrogen levels decline, leading to a loss of bone – and then a variety of other factors. I’ve made two lists. One is what we call non-modifiable—we can’t do anything about these—and the other one is a list of modifiable things.
Age is not modifiable – we’re going to get older – and as we get older, we’re going to lose some bone mass. It’s going to happen to all of us. It happens to men and women. Men tend to have greater bone mass or a larger frame, larger skeleton, tend to be taller in general, so they have more bone mass and so it takes them longer to reach that fracture risk threshold. Gender – women, as I just said, have smaller skeletons in general and so tend to have less bone mass. Race – there’s some ethnic groups that genetically have greater bone density than others. For example, African-Americans tend to have greater bone density than Caucasians or Asians. Having a small body build – that’s just something we can’t do a whole lot about that. If we inherit a small skeleton and we don’t have a lot of height, we’re going to have less bone mass.
For example, Karl Malone, it is going to be a while before he experiences low bone mass because he has such a large skeleton, he’s so tall and large-boned, large physique, and so he’s got a large skeleton. Compare him to a woman who maybe is five feet tall and weighs 100 pounds. She has a much smaller skeleton and much less bone density. Having a family history of low bone mass, again, an inherited thing – and in reality, up to 60 to 80 percent of our bone density is inherited. So that leaves room for variability of behaviors—things that we can do to minimize or maximize our bone density—but to a large degree we inherit our skeleton. Disease – there are some diseases that affect bone density and we can try to manage our diseases well and minimize the effects on our bone, but sometimes diseases will have a negative impact on bone.
Now age of menarche is the age a woman is, or a girl is, when she begins her menstrual cycles. Age of menarche is modifiable and non-modifiable. Sometimes we don’t control, oft times we might not control the age of menarche, but on the other hand, there are many behaviors that a young girl engages in that do delay the onset of menarche. And the later we start our menstrual period; it’s quite highly associated with less bone mass. The earlier we start, the better it is for our skeletons. So things that are modifiable, behavioral things that can affect our bone density, include diet, physical inactivity, physical over-activity, weight, smoking, alcohol consumption, estrogen depletion such as in menopause or not having menstrual cycles, certain medications can have a negative impact on bone, age of menarche, and amenorrhea or the cessation of menstruation.
I want to explain to you how osteoporosis is diagnosed, it’s the bell-shaped curve, so if you already know what it is, you can relax a minute; if not, you need to try to pay attention for just a moment. If we were to take something like ACT scores and see where people scored on the ACT, some would score low, some would score really high – not very many and hopefully not very many down here – but the vast majority of people, the most common score would be right about, if we were to distribute scores, this would be where the most current number of scores are, the most frequent number of scores would be. And in terms of statistics, we call that a zero standard deviation, that’s in the middle. If we wanted to describe the vast majority of people, everybody who got scores from here to here, that would include about 67 percent of the population, and we call that a minus-one, plus-one standard deviation. If we wanted to go a little further out to a minus-2.5 and a plus-2.5 standard deviation, that’s going to account for 95, 97 percent of the population.
Well, the way bone, osteoporosis is diagnosed, is, several men or women were scanned (you’re compared to your own gender, you’re compared to your own ethnicity, you’re also compared to your own age) – and if your bone score falls between minus-one and minus-2.5, that’s diagnostic of osteopenia, or low bone mass. If your score falls below 2.5, then that’s how osteoporosis is diagnosed, and the diagnostic criteria was developed by the World Health Organization. So let’s look at a report of a 24-year-old female who is five-eight and weighs 167 pounds. Comparing her standard deviation scores to her very own age of 24, we call it a Z-score. If we’re going to compare her to 20- to 30-year-old girls, which is what we do after age 30, then we’re going to use her – it’s called a T-score. But because she’s 24, we’re going to use her Z-score. Her total bone density for the hip was a plus 1.2, so she’s actually on the other side for the bell shaped curve, far away from osteopenia and osteoporosis.
Now let’s consider a scan of a 22-year-old female who is five-two and weighs 101 pounds. We measured her spine L1, L2, L3, L4, the four lumbar vertebrae, and her Z-score was minus 2.9. So that fits the diagnostic criteria for osteoporosis. Now do we say that a young girl has osteoporosis? That probably isn’t the best term because she doesn’t necessarily have poor micro-architecture, she doesn’t necessarily have a propensity to fall, but she has a low bone mass. And compared to other 22-years-olds her age, it’s a very low bone mass.
Today I wanted to talk about three factors risks that are related to low bone density, and often these three are interrelated with eating disorders. The first one is body weight, whether it’s our entire body weight or the amount of lean mass that we have. Lean weight is our muscle and organ weight. I want to also talk about menstrual dysfunction; our age of menarche; having oligomenorrhea, which is infrequent menstrual cycles, or amenorrhea, which is the cessation of menstrual cycles. The third one has to do with nutrition. I’m just going to talk about having large calorie deficits. We could have a large calorie deficit just because we refuse to eat enough, and maybe we’re sedentary, we’re don’t necessarily exercise, but we don’t eat enough. On the other hand, it’s common to have a large calorie deficit when we’re extremely physically active, and many athletes don’t realize how much they need to consume to support that work. The other thing to understand is all of these three are interrelated with each other. If I have a low calorie deficit, it frequently contributes to low menstrual dysfunction, to oligomenorrhea and amenorrhea.
If I’m a teenager or preteen, young adolescent, it can delay the onset of menarche. Under-eating also results in a low body weight, which is going to put me at risk for low bone mass as well. Having a low body weight can sometimes contribute to menstrual dysfunction depending on why I have a low body weight, in what composition my body is low, meaning too little percent body fat. So they’re interrelated with one another. Excessive exercise is also related to all three of these. Excessive exercise can lead to a low body weight. It leads to a low total body weight, a low lean mass sometimes. It can contribute to menstrual dysfunction when we exercise too much. And it might not be that we’re exercising too much – it could be that we’re not eating enough calories for the volume of work that we’re doing, which would be the third one.
So, first of all is low body weight. Bones are pretty amazing. They respond to what’s expected of them, and so if we place a big load on them, they’re going to be stronger because their goal is to not break. And if they’re experiencing high loads that make it a risk for them to break, they’re going to respond by increasing bone density, putting in more calcium, and making that site of pressure stronger to resist being broken. So more weight – if I weigh more, I have a bigger load on my bones every day, I’m more likely to have greater bone density. And that’s even just site-specific. If I were to take up tennis, when you look at tennis players, if, for example, I’m left-handed, I played tennis with my left hand, if you were to measure the bone density in my left hand, it would be greater than in my right hand because it’s experiencing a force or a load by hitting the ball with the racquet. And so where we place loads in our skeleton tends to become stronger.
The National Osteoporosis Foundation has set a weight criteria of 127 pounds, meaning anyone who weighs less than 127 pounds is automatically at risk for low bone mass. That’s a small frame, that’s a small skeleton. Sometimes we shouldn’t weigh less than 127 pounds, and then we’re underweight and that maybe even puts us at a greater risk. Two separate studies have been done trying to identify criteria of who may be at risk for low bone mass, and it’s interesting, they both came up with a weight of a 154 pounds, anyone less than 154 pounds may be at risk for low bone mass. Now again, if we inherit a small frame, if we inherit a small body, we’re just at risk. We realize that maybe we are at risk. It doesn’t guarantee we have low bone mass, but we have a greater risk of low bone mass. Lean tissue, our muscle and organ tissue, ends up being really important. The more lean tissue we have, then the better our bone density likely is to be. The thing to understand is people who weigh more, who are a little overweight, have more lean mass because they’re carrying around a heavier load every day, and they actually can have as good a bone mass as someone who exercises a lot and is a smaller person in total weight.
With respect to eating disorders, in trying to predict who is going to have a low bone density, weight by itself was a reliable predictor of low bone mass in the spine, meaning the less you weigh, the less likely you are to have stronger bones in the spine. Body composition considerations – you know, we don’t really have excellent tools to assess how healthy a body weight is for a particular height, and the best tool we have is body mass index, or BMI. And enough large-scale studies have been done and have been done well enough that we’ve developed BMI ranges and can say, “Well, if a BMI is between 18 and a half and 25, that seems to be a healthy range.” That’s a BMI that’s associated with the least amount of premature disease and death. We know that as BMI’s increase, we’re at increased risk for certain premature diseases or premature death. Likewise, when our BMIs are less than 18.5, it is associated with problems of premature disease and death sometimes. The most current range was developed in 1998. It’s going to change again one day I’m sure, but it’s our best tool that we have right now. A BMI less than 18.5 is considered underweight. A BMI of 17.5 or less is the World Health criteria for malnutrition in third-world countries, so as they look at adults – or children, for that matter – and BMI’s less than 17.5, that’s a very strong indicator that that person is malnourished. In terms of diagnosing eating disorders, anorexia, the weight criteria is a BMI less than 17.5. There are other factors that go into diagnosing anorexia, but the weight criteria is a BMI less than 17.5.
So one of the lessons to learn is the goal is not to be as small as you can, and we have that misconception today, that “The less I weigh, the healthier I must be,” and that just isn’t true. We can get too small, weigh too little, be too underweight, and that puts us at risk for disease, and in the case today, of osteoporosis or low bone mass. The other concept to talk about is percent ideal body weight. That has become quite the rave the last five to ten years, is to know your percent fat. The quality of research that exists for BMI and to be able to say that a BMI between 18 and a half and 25 is the healthiest BMI for Americans to be at, that quality of research and quantity of research does not exist for percent body fat. We really cannot say for all Americans, “If you weigh this percent body fat, that’s a healthy percent body fat for you, or that’s too little, or that’s too much.” We really don’t know.
That doesn’t stop people from doing smaller studies and creating a table that says, “Well, if you’re this percent body fat, you’re over-fat, or you’re obese, or whatever.” But you need to understand that we don’t have nationally accepted data on which we can say a percent body fat is a healthy body fat. Furthermore, I could have a BMI of, say, 23 at the age of 20, and at the age of 50, my BMI is still 23. But my body fat could have changed dramatically over those 30 years. What I know is that my BMI is still healthy – my percent body fat could have gone from 19 percent body fat to 35 percent body fat, but I kept the same BMI because I lost muscle tissue and I gained more fat, which is a natural process of aging. And you can’t prove to me that that’s unhealthy; we just don’t know if that’s healthy or not. So I wish we could deemphasize the importance of percent body fat in equating that with health, because the data are not there yet. It doesn’t mean it doesn’t exist – we just can’t quantitate what a healthy percent body fat is – and it’s probably going to be specific for ages throughout the lifespan.
All right, menstruation – having a late age of menarche, starting our menstrual periods later in life, is associated with less bone mass. After age 15 is when we begin to see bone densities decline. We’re better off starting our menstrual cycles at age 11, 12, or 13 or 14 than we are at 15 or 16. In fact, as we look at what amenorrhea, or lack of menstruation means, there are two types – there’s primary amenorrhea and secondary amenorrhea. And primary amenorrhea is menarche after age 16 in a girl with secondary sex characteristics. What things can contribute to a late menarche or to primary amenorrhea? Well, we know that a low percent body fat can be related – in fact, it’s thought that most girls need to achieve at least 17.5 percent body fat or 17 percent, somewhere around there, to begin menstruation. When we stay low in our percent body fat, menstruation’s less likely to occur. Excessive exercise, and that may, again, be due to under-nutrition, or it could just be high volumes of exercise, can delay menarche. Under-nutrition, certainly being malnourished whether it’s a third-world country or whether it’s a girl here in the United States who just is not eating enough for the amount of work that she is doing, can delay menarche.
You know, oft times when we’re not menstruating regularly or when we’re in that critical time and we haven’t starting menstrual periods, we think, “Well, I’ll take a calcium supplement just in case so that I have good healthy bones.” And research has suggested that calcium intake does not make up for the lack of menstruation. It is so important for women to begin their menstrual cycles and to have them, as miserable as they are – they end up being very important for our bones. Secondary amenorrhea, then, is the absence of three or more consecutive menstrual cycles after menarche, and so to have stopped your menstrual cycles for three months in a row is by definition amenorrhea.
Oligomenorrhea is infrequent menstruation, which means menstrual cycles that occur every 35 to 90 days. Amenorrhea that often due to excessive exercise or anorexia. Anorexia frequently results in cessation of menses. Excessive exercise does as well. The other things we’ve talked about, the mechanism behind the cessation of menses is very similar to what’s going on in menopause in older women, and the consequences on bone are the same as menopause. And it’s the way the pituitary and the hypothalamus are unable to send the appropriate messages to the ovaries to trigger ovulation and menstruation. And so in a sense, it’s kind of like being in menopause and the effects on bone are very negative. Amenorrhea for as little as six months can result in measurable changes in bone density. Amenorrheic athletes consistently have spine bone densities ten to 20 percent lower than their regularly menstruating counterparts. Amenorrhea during adolescence may result in irreversible loss of peak bone mass.
There is a very critical period of time when we have our final growth spurt. Our growth plates close within a year or two after the onset of menstruation, and during that time, a lot of calcium is being deposited into bones so that they’re getting longer and bigger. And then after they close, they’re not going to get longer – they’re going to continue to get a little more dense clear up to age 20, 25, maybe up to age 30. But the maximal amount that gets deposited is during that final growth spurt, and if we’re amenorrheic during that period of time or we haven’t even started our menstrual periods, then we might lose an opportunity to have a high peak bone mass that probably is not recoverable later on. We can get some back or we can continue to increase, but it won’t be what we potentially could have had. The incidence of injuries and stress fractures among amenorrheic and oligamenorreheic athletes is higher than it is for menstruating women, so another key point to understand today is that cessation of menses is not a sign of adequate training – it is a sign of overtraining. And it’s astounding the number of coaches today that continue to tell girls, “You know you’re training hard enough when your menstrual periods stop.” Well, no, it’s a sign from your body saying, “This is too much.”
And again, it could be that they just need to eat more. It could be that they need to gain some weight; they need to back off in exercise; they need to have a little more fat on their body. All three of them have been associated with a loss of bone and the amenorrhea, but still, it needs to be addressed. Gains in bone mineral density may be minimal if at all in amenorrheic women. While we’re not menstruating, it’s very difficult to achieve bone gain. Resumption of menses can result in small bone gain, and it depends on when we resume, and I’m going to show you examples today of women who exercised less and were able to start menstruating again and gain a little bit of bone. Well, the common thing to do when someone isn’t menstruating, a girl—an athlete especially—is to put her on birth control or hormone replacement therapy, and research has pretty consistently suggested that hormone replacement therapy will halt further bone loss but will not promote bone gain. It’s not the same as having regular menstrual cycles. It’s much more important for her to menstruate cyclically on her own rather than with the help of birth control pills.
Every couple of years or so, the NCAA looks at the incidence of eating disorders among college athletes, among men and women, and the latest one was published in 1999 in the International Journal of Eating Disorders. They looked at the percent body fat or BMI of women who were menstruating versus those who were not menstruating. It included a variety of activities – it included basketball players, soccer players, as well as dance, gymnastics, track and runners. But these numbers might surprise you for those of you who are familiar with percent body fats. The mean percent body fat where the women were menstruating was 20.9, essentially 21 percent body fat. The mean percent body fat for the women who were not menstruating was 16.2 percent, and it really isn’t uncommon for athletes that need to be small, where appearance is really important, is to have their percent body fats around 12, 13, 14, 15 percent. I hope you’re convinced that not menstruating is not good and that it’s a sign that something needs to change. The BMIs for menstruating women was 21.3, and the BMIs for the women who were not menstruating was 20. The numbers are probably higher than you would expect.
The third one is calorie deficits. Again, calorie deficits can occur just because we’re under-consuming calories for whatever reason, or it could be a result of over-exercise – the volume of exercise we’re doing is so great that either because we don’t understand how much we need to eat or we don’t want to eat that much because we’re afraid we’re going to gain weight-- it’s not being met and so there’s a huge calorie deficit. Actually, the list of problems with large energy deficits is very, very long, but I only put three on here. First is nutritional deficiency, second is rapid weight loss, and third is cessation of menses.
Regarding rapid weight loss, probably some of you are thinking, “Well, what’s wrong with rapid weight loss?” You say rapid weight loss to a dietician, and so many red flags start coming out of his or her head, that it just looks like a hat. Rapid weight loss generally is not safe and not a healthy, desirable thing to do. When we lose weight, essentially we lose weight because we’re burning more calories than what we have, and especially when we’re under-consuming calories that we’re not meeting our basic needs, we’re more or less in a catabolic state. If you think about what your body’s made out of, it’s made up of trillions of cells, and those cells don’t do work for free. They all have a specific assignment – our bones are responsible for being strong and give us structure and allow us to move around, but as we’ve already learned, our bones are busy. They’re always being broken down and rebuilt, and the cells of the bones don’t do that work for free. They need fuel to do that. Your liver consumes about 30 percent of your resting calories. Your liver’s an incredibly busy organ and it doesn’t do work for free—neither do your kidneys or your muscles, obviously. And when we’re under-consuming significant numbers of calories, we’re depriving ourselves of the fuel that they need to do their work, and so they’re going to begin to perform sub-optimally. And over time, that inevitably is going to have a negative impact.
Just to give you an idea of how many calories are required to sustain work, and exercise essentially is work, I created an example of 130-pound person who wanted to exercise an hour a day. If she were to run ten-minute miles, which is kind of slow – kind of fast for me because I’m old – she’d burn about 570 calories in that hour of exercise. Or if instead she wanted to do vigorous aerobics for an hour, that would be still over 500 calories for that hour of exercise. Now if she weighed more, she’d burn more calories because you’re moving more mass in the exercise. Well, how much does she have to eat to support that work? The minimum macronutrient requirements for that amount of work – macronutrients are carbohydrates, proteins, and fats, which are the nutrients that give us calories. Calories are not bad things, calories are very good things. It’s when we consume too many calories that we have a problem, but calories are very good things and very important things to get in the diet. Well, to do that amount of work, she’d need to eat over 400 grams of carbohydrate a day.
I can hardly wait for the low-carb, high-protein phase to go away. It just is not a healthy thing to do. It is especially not healthy for athletes because the fuel the body uses in exercise is carbohydrate, and if you’re not providing carbohydrate in the diet, the body can make some but it doesn’t make nearly enough to support work. Anyway, for a whole day, to not only support that hour of running but also for everything else she needs to do throughout the day, she needs over 400 grams of carbohydrate – right there is 1,650 calories. She needs a minimum of 59 grams of protein, which is another 236 calories. And then to finish meeting her calorie needs and to have some flavor in the food that she’s eating so it’s not like eating the box or the package that the food comes in, I put 50 grams of fat, which is in this particular diet is only 19 percent of the calories from fat. Fat is not an evil thing – fat provides flavor and texture to food, it helps us enjoy what we eat. You can eat a head of lettuce for lunch but it doesn’t taste very good, it’s not very satisfying. Emotionally or physiologically, it’s not very satisfying. Fat is satisfying, and so it helps us enjoy what we eat and be able to relax and be fed emotionally as well as physiologically when we eat. So I put 50 grams of fat – that’s 450 more calories – so in this example, that’s 2,340 calories, and that’s pretty much what this person would likely need if she otherwise had a typical college student lifestyle: walking to class, sitting around a lot. If she is more physically active, she would need more calories.
It is so common, it seems to me, to see young women running an hour a day or an hour and a half a day and trying to live off 1,200 calories. Well, you’re living off less than half of what you need, or approximately half of what you need, and you just can’t continue to sustain that over a long period of time. You don’t provide the fuel for all of your cells to perform optimally and keep every organ system working well. There are a lot of nutrients related to bone health. Calories are important. If we are going to exercise and be physically active, we have got to fuel our work. We cannot have huge calorie restrictions when we’re trying to work. Adequate but not excessive protein is very important. We need enough protein to support maintenance and repair of our tissues. All of our tissues essentially, like our skeleton, are always under construction, being repaired and replaced. High-protein diets actually have a potentially negative impact on bone. Research has shown that high-protein diets decrease the pH of the urine, making it more acidic, which causes more calcium to be lost in the urine. And over time, that potentially could have a negative impact on bone. Of course, vitamin D and vitamin K are important as well.
Well, how much calcium do we need? Well, the recommended intake for calcium, as you look for adults between the ages of 18 and 51, is somewhere between 1,000 and 1,300 milligrams of calcium a day. How much is too much? Well, over 2,500 milligrams exceeds our upper limit, meaning that’s probably too much calcium for the body and it’s going to have a negative impact. When calcium levels are really high in the blood, we try to deposit it and get it out of the blood because it’s not healthy to be in the blood, and it gets put into soft tissues like our kidneys and our arteries and our muscles. Calcium is great if you want a skeleton, but if you don’t want hard skeletal structure in those tissues, then high calcium levels are not a good thing. So keeping in mind that we need around 1,000 milligrams a day, where are we going to get it? Well, the best source of calcium is the dairy group, but not all dairy products are created the same. And if we look at a cup of yogurt, it has about 450 milligrams, or a cup of milk, whether it’s skim, two percent, whole, whatever, a cup of milk is about 300 milligrams. And hence, when we look at the Food Guide Pyramid and it tells us to eat two to three servings a day, two to three servings of dairy products like this are probably going to help us to get up to 1,000 milligrams a day. Cheese, an ounce of cheese is a string cheese stick – depending on what type of cheese it is, anywhere from 200 to 280 milligrams of calcium come per ounce of cheese. Pudding is essentially milk, so half a cup of milk’s around 150 milligrams, so that’s what we see in pudding. Frozen yogurt, cottage cheese, and ice cream, though they’re dairy products, are not nearly as good a source of calcium as is yogurt or milk. A lot of the calcium is processed out in making those things. Pizza can be a great source of calcium, and pizza can be a very healthy choice and part of a nutritious diet as long as we’re choosing healthy pizzas, healthy toppings, healthy crust – hand-tossed crusts, vegetables on top, going easy on the high meat like sausage and pepperoni and hamburger and extra cheese, which add more calories really than anything else. But pizza can be a very healthy part of a diet.
Soda pop is not a good source of calcium – you’d have to
consume a lot of soda pop in order to get your 1,000 milligrams a day. There are other things that provide calcium
in our diet, including things like muffins and waffles and some other things
like that, but the foundation of our diet for calcium comes from dairy. Now I hear all the time, “But dairy’s not a
good source of absorbable calcium, and we need to be consuming vegetables in
order to get a good source of absorbable calcium.” Dr. Weaver at
The last one to discuss is excessive exercise. Excessive training refers to training that is done with an unnecessarily high volume, intensity, or both without additional improvements in conditioning or performance. In other words, we’ve got this exercise schedule where we’re running really far for long periods of time. Maybe we’re doing an hour a day, two hours a day, whatever it is, we’re doing a high volume or we’re doing it at a really high intensity. And even though we’re doing all this work, we don’t seem to be getting stronger or faster. There aren’t conditioning benefits and our performance isn’t improving. That’s because when training loads exceed the body’s ability to recover and adapt, the process ends up being more catabolic than it is anabolic. Catabolic means to break down, and exercise and work actually breaks down lots of tissues, and then in recovery, when the body’s repairing, it makes things stronger or better and more ready to sustain that level of work the next time. But if we don’t allow for repair and recovery, then that doesn’t happen, and overall the result is more catabolic, more breaking down of the body, than it is of repairing and making the body stronger. Hence, it’s very important to have periods of rest—a day or two throughout the week where we’re not exercising so the body can heal and recover.
What are signs and symptoms of excessive exercise? An increased resting heart rate, elevated blood pressure, nausea, frequent illnesses – we’re sick a lot, especially upper respiratory infections, i.e. we have a cold all the time. We have disturbances in our sleep, appetite or mood. We lack energy. We have injuries more often, and it’s slower to get over them. We become irritable and depressed, and of course, our menstrual cycles may stop. I can’t tell you what the cutoff is for excessive exercise because it varies from individual from individual. Our body tells us when we’re exercising excessively, and often we try to push through that but we shouldn’t. We should listen to our bodies and back off. I can tell you that when you look at research in anorexia nervosa and they try to define excessive exercise or see who is exercising excessively, the criteria they use to define excessive exercise is more than an hour a day for six days a week. And I know there are a lot of women on this campus who do that regularly. It doesn’t mean it’s excessive exercise, but in eating disorders, it’s often described that way.
I can also tell you that the miles run per week has been negatively associated with spine bone density. Meaning the more you run, the less spine bone density you’re likely to have. And the great example is the elite endurance runners who often have lower spine bone densities compared to sedentary people. So here we are exercising, being healthy. However, if you measure the spine, it’s lower, often significantly lower, than people who are sedentary. This is a graph in an exercise physiology textbook at the incidence of amenorrhea with miles run per week. So with just five miles a week, which isn’t much, about five percent of women developed amenorrhea. As we get up to 15 to 20 miles per week, up to 20 percent of women—one in five women—will stop menstruating at 15 to 20 miles a week, and that really isn’t a lot of running. But as we continue to run more miles per week, the incidence of amenorrhea continues to increase quite significantly.
What we’ve really been talking about today is something called the female athlete triad. We often think of the female athlete triad as something that happens to collegiate athletes or professional athletes, but not to common girls. I’m here to tell you that recreational athletes can develop the female athlete triad just as dedicated athletes can. The female athlete triad is a syndrome occurring in physically active girls and women. Its interrelated components are disordered eating – and I really haven’t talked about disordered eating today, but it certainly begins to come into play in some of these behaviors – amenorrhea, and osteoporosis. Pressure placed on young women to achieve or maintain unrealistically low body weight underlies the development of the triad. That pressure to maintain an unrealistically low body weight could be self-imposed or it could be imposed by a coach or a trainer. The bottom line is that we’re not maintaining a healthy weight for what our body can handle, and we exercise more, we eat less, whatever it takes, and we develop amenorrhea, disordered eating, and problems with our bones.
I haven’t talked much about eating disorders and bone loss, but some studies have shown that 50 percent of women with anorexia have bone densities that are at least two standard deviations below normal. The thing about eating disorders and bone loss is it affects both cortical and trabecular bone, so that’s what we see in old age, osteoporosis. It leads to compression fractures and kyphosis. Compression fractures are when the vertebrae can’t support the load that they’re carrying and they kind of crush—they break. And you can’t fix those, there’s not a lot you can do about those. They’re very painful and you’re pretty much stuck with that the rest of your life. Kyphosis is curvatures of the spine. The bone loss can be permanent from eating disorders even if you regain weight, which often results in the long-term risk of fractures. The good news is, looking at postmenopausal women, looking at anorexics, when they do gain some weight – five pounds, ten pounds – you can see some gains in bone. The bone will still respond even though we’re out of adolescence. Bulimia often results in oligomenorrhea because it does interrupt hormonal cycles. And it doesn’t matter what our body weight is, bulimic behaviors can contribute to low bone mass because of the effect it has on menstruation.
The last thing I wanted to do is share with you the results of what I thought was an interesting publication. Dr. Jill Lindberg and some colleagues researched about 11 women who were running at least 20 miles a week. They looked at their menstrual cycles and their bone density – I don’t know what else they looked at, and actually, I didn’t look at the original publication. But then 15 months later, they went back and looked at those women again, as many as they could – they found seven – and they reevaluated them. They looked to see if they’d changed their exercise patterns, had they begun to menstruate, had their weight changed, how their bone density changed, all sorts of things like that. I’ve shared with you four of the results of these women, so this is looking at them 15 months later. The first one was 26 years old, and for three years she’d been running 40 miles a week, swimming five miles a week, and cycling 42 miles a week – she was a triathlete. She had had amenorrhea for three years. She stopped her running after the first study, and it took a while – it took almost a year – but her menstrual cycles started again, so she was eumenorrheic, she had normal menstruation. She’d been menstruating for six months. She’d gained four pounds, and probably gaining the four pounds led to eumenorrhea, and her bone mineral density increased by five percent.
The second woman was 31. She’d been running for 20 miles a week and doing aerobic dance for four days a week for a year and a half. She was doing other things before that, and she’d actually been amenorrheic for three years. After the first study, she stopped running. It took a little over a year, but she’d been eumenorrheic for four months when she was retested. She’d gained 6.6 pounds, she hadn’t had any more stress fractures, and her bone mineral density had a huge increase of 11 percent. You know, the thing to notice is these women aren’t gaining 20, 30, 40 pounds, they’re not becoming obese. They’re gaining five, six, seven pounds, they’re backing off on what they’re doing so that they can gain some weight and start menstruation again. There were also two women who didn’t change their behaviors. The third was a 32-year-old female. She was running 24 miles a week for six years. Now think about that – 24 miles a week is not a lot. Now I know there are a lot of women on campus who are doing that amount of mileage. But she had been amenorrheic for four years. She didn’t change her running, she was still amenorrheic, she’d lost another 6.6 pounds, and she had continued to lose some bone mass. The other woman was 28 years old. She was running 45 miles a week for nine years. She had oligomenorrhea for eight of those years, she didn’t change her running, and now she’d become amenorrheic, she had lost 11 more pounds, and she had continued to lose her bone mass.
In conclusion, what would I say? Well, all of this stuff, just to say moderation in all things applies here. Eat a healthy diet. Food is to be enjoyed and to be received with thanksgiving. And we need to eat a variety of foods, an abundance of foods. We need to eat enough to sustain our bodies, and living chronically under-consuming calories just is not a healthy thing, and emotionally it’s not a healthy thing. We need to set realistic goals for and maintain a healthy body weight. If we’re going to choose any type of goal, maybe we should look at a BMI, and anywhere in that range, 18 and a half to 25, is a healthy BMI. Less is not better. Actually, more is. If you want to get a BMI up to 30, that’s even healthier than having a really low BMI. Being a little overweight is much healthier than being underweight. We need to exercise in moderation.
If I can just share personally, I’ve been a runner for almost 30 years and I pretty much do my three miles, and I do it – well, my goal is to do it four to five times a week. The reality is that I do it one to four times a week. It comes and goes – in the summer, I can do a little better and sometimes I can go a little further. But in general I probably run somewhere between nine and 15 miles a week, mostly 12 miles a week. With that amount of exercise, which really isn’t a whole lot compared to what a lot of women are doing, my blood pressure’s below normal. My heart rate is in the low forties, upper fifties. My maximal oxygen consumption is above the 90th percentile for my age. My bones are in great shape, and I’m also to the age where it’s time to start going down. And so that’s a healthy amount of exercise. The outcome I want – to be healthy – is achieved, and my joints are fine. My joints have been running for 30 years and they’re still in good shape and I expect to be able to do it for another 30 years. We need to recognize our body signals. Your body tells you when you’re doing too much. If you are starved all the time, it’s trying to tell you, “Please feed me.” And it is not a sign of strength to overcome that hunger signal – we need to eat. When we have injuries, when we’re tired, when we don’t feel well, when we stop our menstrual cycles--that’s a sign that we need to change our behaviors to maintain a healthy body. Thank you.