Nutrition & Physical Activity
To figure out your basic metabolic rate, it must be measured under very strict conditions such as after a night’s sleep, on a fast, and without any physical activity, etc. What is more common and often more useful is a person’s resting metabolic rate (RMR). RMR is the number of calories you burn to maintain vital functions such as breathing, pumping blood, and maintaining your muscle and nervous system at resting conditions. This is measured under less strict conditions and often does not require the person to fast or to sleep right before the measurement. An accurate RMR measurement requires the use of an apparatus called indirect calorimetry. This can be expensive, so estimating RMR using parameters such as body weight, height, and age can be used as well.
There are three common equations to estimate RMR: (1) the Harris-Benedict equation, (2) the Mifflin equation, and (3) the Cunningham equation. These equations are population specific, so it is important to be aware of their limitations.
Harris-Benedict Equation (widely used and relatively accurate for average body type):
Men: RMR (in calories per day) = 66.47 + 6.23 x Weight (lbs) + 12.67 x Height (in) - 6.76 x Age (yrs)
Women: RMR (cal/day) = 655.1 + 4.34 x Weight (lbs) + 4.69 x Height (in) - 4.68 x Age (yrs)
Men: RMR (cal/day) = 10 x Weight (kg) + 6.25 x Height (cm) - 5 x Age (yrs) + 5
Women: RMR (cal/day) = 10 x Weight (kg) + 6.25 x Height (cm) - 5 x Age (yrs) - 161
Cunningham Equation (uses fat-free mass, suggested for athletes):
For men and women: RMR (cal/day) = 500 + 22 x FFM (kg)
If you would still like to know more about measuring your metabolic rate, such as through an indirect calorimetry, it is recommended to see a health care provider. Columbia students can make an appointment with Medical Services by logging into Open Communicator or by calling x4-2284. You can also visit the Columbia Health site to learn more about services and programs available on campus to help you stay in tip-top shape.
Slow down, but don't give up! Biking, rollerblading, and running are excellent forms of exercise for cardiovascular fitness, improving coordination, and strengthening muscles in your body, especially in your legs. Given that you are just starting out a new exercise routine, you may want to speak with your health care provider. S/he may be able to provide you with a healthy way to start getting in shape based on your fitness level and personal health history.
First things first, it is important to figure out an approximate training intensity, or cardiovascular training zone, at which to exercise. Each individual has an optimal level at which they can exercise that allows the best use of oxygen and energy. Starting out at the level that is right for you will help you build your endurance. The following formula will help you determine your training intensity level:
- Estimate your maximal heart rate (MHR) by subtracting your age from 220. For example, if you are 25 years old, your MHR is 195.
- To figure out your lower limit, multiply your MHR 65%. For example, if your MHR is 195, your lower limit is 195 x 0.65, or 127 beats per minute.
- To establish your upper limit, multiply your MHR by 85%. For example, if your MHR is 195, your upper limit is 195 x 0.85, or 166 beats per minute.
When you first begin to exercise, this intensity level will be fairly low — working out at a higher level could leave you worn out and gasping for air. If working at the 65% level is too strenuous for you to sustain for 20 minutes, begin by working at the 50% level. After a few weeks, when you feel that your endurance and strength have increased, you can increase your training intensity. The goal is to exercise between 65 - 85% of your maximum heart rate. Be aware that as your heart strengthens, it takes less of an effort for it to pump blood to your lungs and tissue throughout your body. Believe it or not, exercise will become easier! You now will be able to increase either the duration or intensity of your workout.
Now that you know your training intensity, in terms of heart rate, you now have a gauge that helps you monitor how hard you are exercising. About twenty minutes into your workout, stop and take your pulse for 15 seconds (after 15 seconds your heart rate begins to drop), and multiply the number of beats by four. If you are in your target zone, keep going at the pace you were at. If you are above or below, then you know to either decrease or increase the intensity level of your exercising. After a while it will either become second nature to you, or you will begin to know your body and be able to estimate the right intensity level for you. These assessments will help you exercise longer before feeling tired, and you will get a much better workout.
It also helps to stretch and slowly warm up before exercising and not to overdo it in terms of the duration and frequency of workouts. Start out with 20 to 30 minute sessions, working slowly up to an hour. Don't try to get a really good workout every day of the week — this could lead to burnout. Try to exercise about three to five times a week, and vary the intensity or type of activity. If you smoke, cutting down or stopping will help significantly to increase lung capacity. Also, speaking with a health care provider before you change your exercise routine is always a good idea. S/he may be able to provide you with a healthy way to start getting in shape based on your fitness level.
Now that you’ve read up on exercise, get ready for takeoff! Set reasonable goals for yourself, (for example, exercise three times a week for 30 minutes). If you are not as "in-shape" as you want to be this summer, make it your goal to reach that level next summer, and stay active all year long. Remember to take it slowly — a good base for fitness can be maintained for the rest of your life.
January 4, 2013521120
Before discussing their role in maintaining good health, let's first clarify what antioxidants are. "Antioxidant" is the collective name for the vitamins, minerals, carotenoids, and polyphenols that protect the body from harmful free radicals. The most well known antioxidants include the vitamins A (found in liver, dairy, and fish), C (found in bell peppers and citrus fruits), E (found in oils, fortified cereals, seeds, and nuts), and the mineral selenium (found in Brazil nuts, meats, tuna, and plant foods). The carotenoids beta-carotene, lutein, and lycopene also have high antioxidant activity and are responsible for adding color to many fruits and vegetables. Carrots and pumpkins wouldn't be orange without beta-carotene, for example. Lutein, also important in eyesight, is abundant in leafy green vegetables. Lycopene is present in red fruits and vegetables, most notably in tomatoes. No wonder why many experts stress the importance of eating a "colorful" diet!
So why are they called antioxidants? The name is indicative of the mechanism by which they help prevent disease. In humans, a small but significant percentage of oxygen molecules in the body will become electrically charged due to natural cellular activity and/or exposure to environmental factors such as tobacco smoke and radiation. The oxygen molecule becomes a "free radical" as it undergoes this process of oxidation. Free radicals are highly reactive as they try to steal electrons from other molecules, including DNA and cellular membranes. They will continue to react with other cellular molecules in a chain-reaction mechanism. This chain reaction of free radicals can damage cells, which may play a role in the development of certain conditions like heart disease and cancer. Antioxidants, however, stop the chain-reaction by giving up electrons and neutralizing free radicals so that they cannot induce any more oxidative damage. Unlike other molecules, antioxidants do not become reactive when they lose an electron.
Many studies have shown the link between free radicals and a number of degenerative diseases associated with aging. Thus, it is possible that antioxidants can be beneficial in reducing the incidence of cancer, cardiovascular disease, cognitive impairment, Alzheimer's disease, immune dysfunction, cataracts, stroke, and macular degeneration.
Read any fitness magazine, watch a few television ads, or simply pass by your local health food store, and notice the benefits of the latest supplement being touted. While new products emerge frequently, it is best to remember that vitamin and mineral supplements are not to be used as substitutes for a healthy, well-balanced diet. In fact, due to many conflicting studies on the effects of antioxidant supplements, the American Heart Association does not currently recommend using antioxidant vitamin supplements. It is also important to note that we can "over-supplement" our bodies, taking much more than the recommended daily value of certain vitamins and minerals. Vitamins A and E are fat soluble, meaning that excess amounts are stored in the liver and fatty tissues, instead of being quickly excreted, creating a risk of toxicity. Your best bet is to eat a diet rich in fruits, veggies, and whole grains.
For information on cancer, heart disease, and antioxidants (as well as on healthy diets, vitamins and minerals, etc.), you can visit the the National Cancer Institute website. Additional resources on supplements are provided by the National Institute of Health's Office of Dietary Supplements.
Remember, a balanced diet rich in colorful fruits and vegetables can provide you with immediate health and energy benefits and help fight the effects of aging for years to come. Happy antioxidizing!
Cholesterol is a necessary component for living cells. However, high levels of blood cholesterol are associated with an increased risk of heart disease. To complicate matters even more, blood cholesterol can be divided into two types, one of which actually lowers the risk of heart disease! To get the story on cholesterol straight, it's necessary to understand something about how cholesterol works in the body and how it can contribute to heart disease.
Most of the cholesterol in the body is produced by the liver. A significantly smaller amount comes from dietary sources, such as meat, eggs, and dairy products. Cholesterol travels throughout the body via the blood stream, being absorbed by cells along the way to be used for important processes, such as hormone production and cell membrane repair. Because it isn't water soluble, cholesterol is ferried along the bloodstream encased in protein. These cholesterol-filled protein orbs are called lipoproteins. Lipoproteins come in a variety of sizes that behave differently from one another. Broadly, health care providers and scientists talk about low-density lipoproteins (LDL) and high-density lipoproteins (HDL).
The role of both types of cholesterol in heart disease centers around the formation of arterial plaques — fatty, filmy deposits on arterial walls. Over time, plaques become hardened, leading to narrow, rigid arteries that impede blood flow and thereby increase the risk of heart attack. Also, smaller plaques sometimes develop blood clots on their surface, which can then detach and go on to block arteries downstream, potentially leading to heart attack. Although the biochemistry involved isn't simple, the take home message is that LDL contributes to the formation of plaques on the artery walls, while HDL helps prevent their formation. Accordingly, LDL is often called "bad" cholesterol while HDL is called "good" cholesterol. (These terms apply only to blood cholesterol; dietary cholesterol is neither good nor bad in this sense.)
For more information on cholesterol and heart disease, read the Related Q&As listed below.
Dear Not worried...just curious,
If your diet is leaving you drowsy, it may be related to not eating enough calories — especially since many vegetarian foods tend to be relatively low-calorie. Eating too few calories would leave your body without enough energy to "get up and go" in the morning. To increase your calorie intake, try buying a variety of nuts, seeds (sunflower, pumpkin, etc.), and dried fruits to make your own trail mix: each day, put about one cup into a bag and carry it with you to snack on. Besides added calories, you will also be getting a good source of vitamins, minerals, and some protein into your diet.
At meal times, include healthy size portions of grains (whole wheat, brown rice, oats, barley, buckwheat, etc.), vegetables, fruit, and legumes (dried beans and peas), and use a moderate amount of vegetable oil (canola and olive are good choices) for cooking. If you eat eggs and dairy, they can also serve as a great source of protein, calcium, and added calories.
In terms of exercise, aim for about 30 minutes of aerobic activity five or more times a week to get cardiovascular and energy-boosting benefits. Exercise in excess of about one hour of aerobic activity, five or more times a week, should be reserved for those training for a competitive sport (and who are eating higher-calorie diets!). High levels of exercise increase the risk of sports-related injury and may make it harder to take in a sufficient amount of calories.
Even if you think you sleep the right number of hours, keep in mind that some people, particularly college-aged people, require up to ten hours of sleep a night. Other sleep habits might also give you problems; for example, it's important to try to go to bed and wake up at close to the same time each day. Although this may seem nearly impossible on a student schedule, try to get on an even keel to start off the semester. If you wake up at 11:00 AM most days and get up for an 8:00 AM class two days a week, you most likely will feel like you never quite wake up on the two early days, even if your total amount of sleep is adequate. You may want to adjust your routine so that you go to bed early enough to wake up at the same time each day (weekends included), and see if your tiredness improves.
If you feel overly exhausted or your drowsiness is interfering with school and life activities, you may want to consider seeing your health care provider. Students at Columbia can make an appointment through Open Communicator (Morningside) or by contacting the Student Health Service (CUMC).
Good luck getting up and at 'em!
Dear Shaky Sharon,
Hypoglycemia, or low blood sugar, often happens because we go too long without eating. Some symptoms of hypoglycemia may include dizziness, mental confusion, anxiety, shakiness, and weakness. Reactive hypoglycemia is a chain of events. It refers to a state when our blood sugar is low, which causes a person to eat a concentrated sweet, and then insulin is overproduced by our pancreas and our blood sugar drops even further than where it was before. A more serious condition, Spontaneous Hypoglycemia, results in chronic low levels of blood sugar. This is a very rare condition, and medical attention is required.
In a hypoglycemic diet plan, you eat every two to three hours. Mixed meals and snacks, including carbohydrate, protein, and a little fat, are recommended. An easy snack to keep with you that fits this bill is peanut butter crackers, either prepackaged or home made. Other appropriate snacks include low-fat yogurt and low-fat trail mix. Try to avoid eating concentrated sweets, such as candy and sugary drinks, as these can cause blood sugar to drop even further. Finally, drink plenty of water. Many symptoms of in-between meal "lows" are caused by dehydration.
To determine the cause of your hypoglycemia, it best best to see your health care provider. S/he may be able to discuss your individual risk factors for diabetes. S/he may also refer you to a nutritionist, who can help design an eating plan to suit your specific needs. If you are at Columbia, you can make an appointment with Medical Services through Open Communicator or by calling x4-2284.
Dear Confused by the news,
While this sounds like such a simple question, it's really not. First, what is ideal? The amount of calories needed to maintain each individual's weight appropriate for optimal health? The amount a person needs to maintain an unnaturally thin weight that meets false societal ideals? The amount an athlete needs to perform at her/his best? Reality tells us that the ideal caloric intake is different for everyone.
Caloric needs depend on age, gender, height, present weight, body frame, physical activities, hormones, and weight plans (maintain, gain, lose, etc). An intake between 1200 and 1400 calories per day is considered a low intake. This calorie level is just able to meet what are called basal metabolic needs, or the calorie needs to keep the heart beating and all the internal organs working. Calorie levels below 1200 should be avoided, because they may decrease metabolism and are usually hard to follow for any length of time. Very low caloric intake may promote binge eating due to the feeling of deprivation, and may be deficient in one or more nutrients. Some liquid diets call for fewer than 1200 calories, however, their long-term effectiveness is controversial, and they should only be followed under the supervision of a physician.
The Daily Values (DVs) used on food labels base their nutrient intake on a 2000 calorie per day diet. This was a result of many long meetings with nutrition experts who concluded that 2000 calories was the average amount needed by American adults. Therefore, short, thin females who are not active, will have caloric needs below 2000. For those who are "average" size and get moderate activity, caloric needs to maintain weight should be about 1600-2400 per day.
Instead of just worrying about a number of calories, have you tried listening to your own internal needs? Have you set goals related to healthy eating? Consider a focus on maintaining a balanced eating plan that includes a strong base in whole plant foods (fruit, vegetables and grains) and eat a moderate amount of healthy fats. Also don't go overboard on eating food just because it is fat-free (i.e. a whole box of "fat-free" cookies). Although fat calories are most easily converted to fat in the body, all calories from fat, carbohydrate and protein count! Finally, don't forget food should bring some pleasure to life and serves many needs other than energy functions.
If you would like to explore your individual caloric needs, or have other nutrition questions, Columbia students can make an appointment with the nutritionist at Medical Services (Morningside) or at the Student Health Service (CUMC). Columbia students may also want to check out Get Balanced! for tons of nutrition resources and information, including th Guide to Healthier Eating. You can also review many options and create your own plan using the online resources at MyPlate. Have fun determining the right balance for you and your goals. Remember to try new foods and new food cominbations — there are lots of healthy and tasty options. Eat and be well!
Dear Cow lover,
Why does a milking stool have only three legs? Because the cow has the udder! Get it? Unfortunately, there’s not such a definitive answer to YOUR question. Research on the health effects of drinking milk has produced mixed results. As with any other food group, it is important to consider the pros and cons of dairy consumption.
Before a discussion of pros and cons, here is a run-down on recent milk research as it relates to osteoporosis. Although it is thought that drinking milk every day helps ward off osteoporosis, a small group of renowned researchers recently found that drinking too much milk can actually contribute to calcium loss. This is because the high amount of protein in milk thins blood and tissue, causing it to become acidic. In order to neutralize the acidity, the body draws out calcium from bones. As a result, the more milk you consume, the more calcium you need to process the protein intake. With that being said, drinking moderate amounts of milk each day (500 to 700 milligrams daily) is still thought to be good for your bones. More information on osteoporosis can be found in Women, calcium, and osteoporosis?
Moooving on, here is a list of the various pros and cons of drinking milk:
- Milk is high in calcium, which is important for healthy bones. Additionally, the calcium in milk is well absorbed by the digestive tract because the vitamin D and lactose found in milk facilitate calcium absorption. Still, it's possible to get ample calcium without drinking dairy milk — by eating foods such as tofu, soy milk, or greens such as kale. See Calcium — how much is enough? for more information.
- Whole milk is brimming with protein, which is beneficial for muscle growth.
- Studies have shown that drinking milk can help regulate weight gain.
- Skim milk is very low in fat and cholesterol, and is a complete source of protein.
- Milk is also a good source of phosphorous, magnesium, vitamin A, vitamin D, and riboflavin (a B vitamin).
- Whole milk is high in saturated fat, which can increase cholesterol level.
- Milk is a common cause of food allergy (allergy to milk protein).
- Many people lack the enzyme to digest lactose (milk sugar). This is called lactose intolerance, which causes bloating, gas, and diarrhea.
- Milk may contain the antibiotics given to the cow while it is lactating. It has been argued that humans subsequently absorb these antibiotics upon drinking milk, potentially leading harmful bacteria to become more resistant to these antibiotics. As a result, when antibiotics are prescribed, they may not be as effective at killing the bacteria.
- Some research has found a correlation between drinking milk that is produced by cows injected with the bovine growth hormone (rBST) and cancer. However, research shows highly mixed results.
As a side note, if you are concerned about the possible effects of antibiotics and rBST on your body, it is possible to buy antibiotic-free (and typically hormone-free, as well) milk from specialty grocers that carry natural foods. Alternatively, you can purchase USDA-certified organic milk, which is available at most supermarkets.
Overall, when researching the pros and cons of milk, it is important to take into account that there are two opposing sides — one that believes that milk is great for the body, and another that believes that milk does not aid against osteoporosis and is even harmful for the body. Whatever camp you choose to join, it is important to be informed. Seize every opportunity (to obtain information), and milk it for all its worth!
Dear The hulk-ette,
You've touched on two commonly misunderstood components of exercise. Despite what all the late night infomercials tell us, fat and muscle are two distinctly different tissues and one can't be turned into the other. Muscle will always be muscle and fat will always be fat. As to the second thought you mentioned, one pound of either is exactly that — one pound.
It is indeed a myth that fat cells can change into muscle. You can burn fat and build muscle, but a fat cell will never turn into a muscle cell. Body fat is a storage place where our body puts extra energy when we consume more calories per day than we burn. If someone continues to consume more calories than s/he needs, the size of their existing fat cells increases. When we "burn fat" we are actually shrinking the size of our fat cells by using the energy that has been stored there. There are also have a fixed number of muscle cells so when we are building muscle the individual muscle cells are increasing in size (bulking up).
Over time, you can gain muscle mass through a variety of activities including weight lifting and other forms of resistance training. If your main goal is to bulk up, you are likely increase your muscle mass which could increase your overall weight. Remember that your weight also depends on what you eat and if you're doing other types of exercise. For example, if you're doing lots of cardio, then you may ultimately lose fat and decrease your weight.
Instead of stepping on a scale, you may want to consider measuring your body composition. Methods to assess body composition (lean body mass vs. fat body mass) can help give you a more accurate idea of what comprises your body. The related Q&As below contain many useful tips to guide your training.
You can always talk with a Registered Dietitian (RD) or a trainer to help determine the weight and exercise plan that's right for you. At Columbia, nutrition appointments are available by calling x4-2284 or logging in to Open Communicator, and personal trainers are available at Dodge Fitness Center. You can also join the CU Move initiative, Columbia's online physical activity program. CU Move encourages members of the Columbia community to engage in active lives that include regular physical activity. The program provides participants with motivation and incentives to be active throughout the year. If you are not a student at Columbia, check with your local fitness center or health care provider for nutrition and exercise referrals.
Choosing to be active can help you feel better now and for years to come — thanks for helping us bust some common exercise myths.
While jetting cross-country can be a fun adventure, coping with jet lag is often an unwelcome effect. Jet lag is a temporary disorder that occurs when air travelers rapidly travel across three or more time zones. Traversing time zones appears to interfere with a person's production of melatonin, a hormone that helps regulate our sleep-wake cycles (see Melatonin from the Go Ask Alice! archives for more information). This may explain why jet travel disrupts our sleeping patterns and why it takes a while for us to adjust to a new time zone. Travelers have the option of taking melatonin to help counteract the effects that flying has on getting a good night's sleep.
Taking melatonin to reduce jet lag is a well-tested and safe use of the hormone. When the goal is to be in bed and asleep during the normal nighttime hours of your destination, timing is everything. If you take melatonin at the wrong time while still at home in New York, you may land safely in London, but your inner clock may be wandering around the Los Angeles airport wondering how it got on the wrong flight! So, what's the trick?
The secret to shifting your internal clock lies in the direction of your flight and duration of your journey. Travelers who cross three or more time zones generally require more time to adjust. Depending on your travel direction, it is recommended to take melatonin as follows:
- Westward travel is associated with early evening sleepiness and predawn awakening. When traveling westward, melatonin can be taken in the morning.
- Traveling to the east is associated with struggling to fall asleep at the destination bedtime and difficulty arising in the morning. In this case, it is best to take melatonin in the evening at your local time.
- Melatonin can be taken 30 minutes before sleeping. You can also ask your health care provider about the right time to take it.
- Though side effects are uncommon, it is a good idea to avoid alcohol when using melatonin.
The severity of jet lag is also dependent on whether a person is able to sleep while traveling, their age, and the availability of local circadian time cues at the destination (such as natural sunlight). Other than taking melatonin, your health care provider may recommend that you:
- Avoid alcohol, large meals, and caffeinated beverages during travel
- Eat meals at the appropriate time of your destination
- Drink plenty of water
- Sleep, if possible, during long flights
- Consider timed bright light exposure prior to and during travel
- Take sleep-inducing medications, such as zolpidem (Ambien), eszopiclone (Lunesta) and zaleplon (Sonata), during travel and to help you sleep during the first couple of days after your arrival
While adjusting to a new time zone may seem like a drag, don't worry, for your body will adjust in due time. Jet lag may last for several days, but it is a temporary condition that is normally manageable. Whether or not you choose to take melatonin depends on the severity of your jet lag and your preference to induce sleep. In the meantime, don't forget to adjust your watch as well. Happy (and restful) travels!