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Posts from the “Myths” Category

True or False: Carbohydrate loading improves aerobic exercise performance?

Posted on June 6, 2019


Carbohydrate loading, also sometimes referred to as carb or carbo loading, glycogen loading and glycogen super compensation, is a strategy used by athletes to improve performance in endurance events usually lasting longer than 90 minutes.

The practice has been around since the 1960s, when scientists first noticed that low-carbohydrate diets resulted in depleted glycogen stores and quicker fatigue in research participants. These studies also showed that eating diets high in carbohydrates resulted in enhanced glycogen stores and prolonged endurance times.

Glycogen is carbohydrates (energy) stored primarily in the liver and mus- cles. When we exercise, we draw on glycogen for fuel. When we engage in long endurance events—a marathon, triathlon or 100-mile cycling race, for example—our glycogen stores become very important. Without energy to keep our bodies going during these long-distance challenges, fatigue sets in faster, and our overall performance is greatly diminished.

The first protocol used for carbohydrate loading, often referred to as the classic approach, had athletes drastically cutting back on carbs 5–6 days before an event and doing lots of intense exercise. They took in an abundance of carbs 2–3 days before the event, at the same time reducing their activity level.


The goal was to deplete glycogen stores, both by cutting back on carbs and doing the intense exercise, so that when they upped their carbohydrate intake, cells in the body would be much more receptive or sensitive to carbohydrates and to storing them for future use.

This classic approach worked, but it wasn’t popular with athletes. If you have ever tried to perform intense exercise on a low-carbohydrate diet, you know why. Subsequent studies have shown that you don’t need to go through the glycogen-depleting process in order to improve performance with carbohydrate loading.

Now the general protocol for carbohydrate loading is to increase carbohydrate intake 2–3 days prior to an event and to combine that with tapered or reduced activity.

Many studies on athletic performance have shown that carbohydrate loading improves performance by 2–3%. at might not sound like a lot to some people, but in a marathon, that could be the difference between win- ning and not even finishing in the top 10–20% of runners.

Sedlock (2008), in an article published in Current Sports Medicine Reports, stated that the ergogenic (performance-enhancing) value of carbohydrate loading and associated physiological mechanisms has likely been studied more than any other singular performance-enhancing strategy. She also states that the ergogenic benefit of carbohydrate loading for endurance performance is a widely accepted tenet.

So yes, carbohydrate loading does improve aerobic performance. For most of us who are considered general recreational athletes, we will probably never need to go through a carbohydrate-loading regimen. As I finish this chapter, my cute little dog Scout is looking at me with great anticipation to take him for a walk, which I am gladly going to do. Carbohydrate loading likely wouldn’t help me much during that 30-minute outing.

However, if you are planning on participating in an endurance activity that will last 90 minutes or longer, then carbohydrate loading could help delay fatigue and have a positive impact on your overall performance.

Sedlock, D.: The latest on carbohydrate loading: A practical approach. Current Sports Medicine Reports (2008), Vol 7, pp. 209-213.

True or False: Eating garlic lowers cholesterol?

Posted on April 24, 2019


GARLIC (ALLIUM SATIVUM) is often used to flavor foods and is well known for its strong, distinctive odor. Because of its aromatic properties, garlic is sometimes affectionately referred to as the “stinking rose.”

Many years ago my wife and I went to San Francisco to attend a conference, and while on a long walk we came across a restaurant called The Stinking Rose. She LOVES garlic, so we decided to stop for dinner.

I’ll never forget the overwhelming smell of garlic when we walked in    the door. I’ll also never forget the first item on the menu: 50 Clove Garlic Chicken Breast—chicken breast adorned with 50 cloves of garlic. My wife was in heaven!

Garlic contains allicin, which has been shown to kill some bacteria and fungi. Garlic is touted for having many health benefits such as preventing colds and the flu as well as lowering high blood pressure and  cholesterol.

But let’s focus on whether garlic is effective at lowering cholesterol, and let’s begin by reviewing the two types of cholesterol we measure: LDL and HDL.

LDL, or low-density lipoprotein (often called bad cholesterol), is a fat/ protein complex that carries cholesterol to the arteries and contributes to cardiovascular disease.

HDL, or high-density lipoprotein (often called good cholesterol), is a fat/ protein complex that carries cholesterol from the arteries to the liver for removal and helps decrease the risk of cardiovascular  disease.

Health professionals recommend keeping total cholesterol below 200 mg/dl and LDL cholesterol below 100 mg/dl. Ideally, HDL should be 60 mg/dl or higher.

Now back to garlic. Garlic can be eaten raw or can be taken as a supplement available as a powder, tablet or capsule. Garlic is generally considered to be safe, but there can be some mild side effects from garlic such as bad breath, general body odor and gastrointestinal distress.

It is also important to note that garlic can affect the body’s ability to clot blood, so individuals taking a blood thinner should talk to their physician if they decide to start eating lots of garlic or taking a garlic supplement.

The author Khoo (2009) published a meta-analysis in the Journal of Clinical Pharmacy and Therapeutics on whether garlic lowers cholesterol levels. Khoo identified 1,228 research articles on garlic and, using strict inclusion criteria to ensure that he chose only studies of the highest quality, identified 13 research studies that tested 1,056 subjects. Khoo’s findings: “The available evidence from randomized controlled trials does not demonstrate any beneficial effects of garlic on serum cholesterol.”

Khoo also states that recommendations by proponents of complementary and alternative medicine to increase garlic consumption as a way to reduce the risk of cardiovascular disease should be viewed with caution.

I’m not a huge garlic fan, but I do think it adds a desirable flavor to many of the foods we prepare at home. If my wife and I ever take another trip to San Francisco, you can bet that we will likely make a repeat visit to The Stinking Rose restaurant.

Khoo., Y.: Garlic supplementation and serum cholesterol: a meta-analysis. Journal of Clinical Pharmacy and Therapeutics (2009), Vol 34, pp. 133-145.

True or False: Grapefruit juice can impact many medications?

Posted on April 2, 2019


I WASN’T MUCH of a grapefruit fan growing up—that is, unless my mother cut the grapefruit in half, separated the pulpy and meaty portion of the fruit from the tough—and sometimes bitter—skin surrounding it, and covered the entire surface with sugar.

I find it interesting that my kids are the same way—and they weren’t even around when I was growing up! As an adult I now enjoy peeling a grapefruit and eating it slice-by-slice, the way most people eat oranges.

Grapefruit is healthy; it’s low in calories, it contains lots of vitamins and minerals, it’s a good source of fiber, and it contains antioxidants. Most of us can consider grapefruit a “safe” fruit.

However, it is true that grapefruit or its juice can have a negative impact on many medications. You should exercise caution if you take medication and you want to eat grapefruit or drink grapefruit  juice.

Grapefruit juice doesn’t interact directly with medications; it inhibits an enzyme in your small intestine that works to break down certain medica- tions. Interfering with that enzyme can result in too much medication enter- ing your blood, potentially leading to a dangerous situation.

This phenomenon was accidentally discovered in the late 1980s. Researchers investigating the interaction of alcohol and the prescription drug felodipine used grapefruit juice to cover up the taste of the alcohol. However, one result of the study was a large increase of felodipine in the blood of research participants.

Grapefruit juice can also have the opposite effect, lowering the concentra- tion of a few medications in the blood.

There are dozens of medications that can be negatively affected by grape- fruit juice, including those for pain control, hypertension, allergies, high cholesterol, depression, epilepsy, heart disease and asthma.

In an article published in Nutrition Journal, authors Kiani and Imam (2007) state, “Grapefruit juice is consumed widely in today’s health-conscious world as a protector against cardiovascular disease and cancers. It  has, however, been found to be an inhibitor of the intestinal cytochrome P-450 3A4 system, which is responsible for the first-pass metabolism of many drugs.”

The authors also cautioned, “In light of the wide-ranging effects of grape- fruit juice on the pharmacokinetics of various drugs, physicians need to be aware of these interactions and should make an attempt to warn and educate their patients regarding potential consequences of concomitant ingestion of these two items.”

Other citrus fruits that may interact with medications  include  Seville oranges and tangelos. Lemons, limes and regular oranges generally are thought to have a low risk of interacting with  medications.

If you take prescription or over-the-counter medications, have a conversation with your doctor or pharmacist if you wish to eat grapefruit or drink grapefruit juice.

Kiani, J., & Imam, S.: Medicinal importance of grapefruit juice and its interaction with various drugs. Nutrition Journal (2007), Vol 6, pp. 33-41.


True or False: Honey is an effective cough suppressant?

Posted on December 17, 2018


HOME REMEDIES FOR the common cold and other minor ailments often have great appeal because of reduced cost and decreased risk of side effects, which might not be the case with prescription medications. For decades, parents turned to over-the-counter cough medicines containing drugs such as dextromethorphan or diphenhydramine to relieve their children’s nagging coughs.

As parents of three, my wife and I have spent a fair number of near-sleepless nights consoling our restless children when they were suffering from hacking coughs. I remember making more than one trip to the grocery or drug store late into the evening hours to fetch cough medicines we thought would help.

That ceased in 2007, when the Food and Drug Administration questioned both the effectiveness and safety of these cough suppressants for young chil- dren. That’s when we started looking for a more natural remedy for our kids’ persistent coughing, and that’s when we first tried honey. As we talked to more parents, we learned that many of them used honey to help control coughing in sick children.

We discovered that honey really does work, and it has been verified in a number of published studies. One high-quality—in other words, randomized, double-blind and placebo-controlled—research investigation conducted by Cohen and colleagues (2012) and reported in the journal Pediatrics examined the effect of honey on nocturnal cough and sleep quality.

In the article, the authors conclude, “Parents rated each of the honey products more favorably than the silan date extract (placebo) for symptomatic relief of their children’s nocturnal cough and sleep difficulty due to upper respiratory tract infections (URI). Honey may be a preferable treatment of cough and sleep difficulties associated with childhood URI. In light of this study, honey can be considered an effective and safe treatment of children greater than 1 year of age.”

Caution: You should avoid giving honey to children under 1 year of age, as there is a risk of botulism.

Honey could help control coughing by coating the back of the throat, thus reducing irritation from persistent coughing. And honey has antioxidant as well as antimicrobial properties that might be beneficial. The sweet flavor of the honey could result in a child’s body creating more saliva, thus reducing the thickness of throat mucus.

You can mix a teaspoon or two of honey with warm water or tea, or you can just take the honey directly. Mixing the honey with warm liquids dilutes it some and potentially reduces the effectiveness. If you or your children can stomach it, try mixing the honey with vinegar. We’ve found this to be even more effective than just plain honey. (Vinegar will have its own chapter in another volume.)

One other caution: Some children are allergic to honey, as we learned when we gave our middle child his first-ever teaspoon of honey late one evening for his cough. His body’s reaction resulted in a trip to urgent  care.

We usually try to control a cough only if it is persistent or is disrupting sleep. All coughing isn’t necessarily bad; it is one way your body works to clear mucus from your  throat.

If you’ve never thought about using honey to help control coughing, I’d recommend giving it a try. It has really worked for our family. And if you’re feeling especially brave, mix it with a teaspoon of vinegar.

Cohen, H., Rozen, J., Kristal, H., Laks, Y., Berkovitch, M., Uziel, Y., Kozer, E., Pomeranz, A., & Efrat, H.: Effect of honey on nocturnal cough and sleep quality: a double blind, randomized, placebo-controlled study. Pediatrics (2012), Vol 130, pp. 465-471.

True or False- Jell-O is good for your knees because it has ground up cartilage in it?

Posted on August 19, 2018


We established in chapter 15 that gelatin is made by boiling the bones, skins and hides of cows and pigs. When I sent that chapter to my editor, she said it reminded her of a tape she listened to years ago that described how eating cartilage from chicken bones was helpful in preventing arthritis.

She also said she consumes two envelopes of unflavored gelatin every morning to help stave off arthritis. Let’s explore if that is really effective.

Whether you talk to highly competitive athletes or to individuals in their 60s, 70s or 80s, joint pain is a common complaint. I spoke to a group of retired educators shortly before I wrote this chapter, and following the presentation, I had a long discussion with a woman who said she doesn’t exercise at all because of pain in her knees.

As someone who has been working in the areas of health and fitness for the past 20 years or so, I can confidently say that I’ve heard this complaint hundreds of times.

When the cartilage that  covers  our  bones  (called  hyaline  or  articular cartilage) incurs damage, we experience inflammation, pain and decreased range of  motion. Because this  affects millions upon millions of people, it makes sense that we might look for simple and inexpensive remedies such as taking  gelatin.

From the reading I’ve done, it appears that gelatin is good for strengthening hair and fingernails and for protecting our joints. This might be a legitimate claim, because gelatin contains the amino acids proline and glycine, which are thought to be particularly important for healthy cartilage.

As I began conducting research for this chapter, it became obvious that there is very little published research on the topic. I did find a report of a study conducted at Ball State University indicating that a gelatin supplement improved joint pain in athletes. Unfortunately, the study was never published in a peer-reviewed scientific journal, nor were the details or specifics of the study released.

Plus this particular study was funded by the company that created the supplement, raising even more questions about its validity.

In an online WebMD article, Timothy McAlindon, M.D., MPH, was quoted as saying, “If gelatin was protective [for stiff knees] there’d be less osteoarthritis in this country and not more, because it’s widely contained in foods.”

There is some evidence that pharmaceutical-grade collagen hydrolysate (hydrolyzed gelatin products) may be beneficial in the treatment of osteoar- thritis and osteoporosis. In a review article on the topic, Moskowitch (2000) stated, “Collagen hydrolysate is of interest as a therapeutic agent of potential utility in the treatment of osteoarthritis and osteoporosis.”

“Is of interest” certainly doesn’t equal good scientific evidence, in my opinion. In addition, the studies conducted with gelatin supplements and pharmaceutical gelatin are using different and more-concentrated forms of gelatin then you would find in, for example, commercial Jell-O.

I will continue to enjoy Jell-O on occasion; however, I don’t believe it will improve the health of my knees, which have been subjected to a number years of self-inflicted abuse from wrestling, track and football.

Reference: Moskowitch, R. Role of Collagen Hydrolysate in Bone and Joint Disease. Seminars in Arthritis and Rheumatism (2000), Vol 30, pp. 87-99.

True or False- Freshman in college gain on average 15 pounds?

Posted on June 17, 2018


We often hear “The Freshman 15” to express the amount of weight supposedly gained by students in their first year of college. I’ve had the privilege of teaching health-related courses on college campuses in New York, Colorado and Wisconsin, so I’ve often dealt with this topic in classes and in my speaking engagements.

It is indeed true that most college students gain weight during their first year; however, it is not nearly 15 pounds. We’ll talk more about the actual number in just a bit.

First, I would like to explore factors that contribute to weight gain in college freshmen. One is alcohol consumption. A single drink can contain from 100–150 calories, so a student who consumes eight or 10 drinks in a night out with friends could be adding 800–1,500 calories that day. And students who have been drinking are often more likely to make a late-night food run; Taco Bell is one favorite. Those extra calories add up!

Some students get into trouble with the buffet/cafeteria-style all-you-can- eat dining services available on most college campuses. They return for two or three entrees, a variety of not-so-healthy side dishes and multiple high-calorie desserts. Who wouldn’t be tempted to end each meal with a huge soft-serve vanilla ice cream cone! Again, the new lifestyle offers lots of extra calories.

Many college students are less active than they were in high school. When I pose the question of how many students were involved in two or three sports in high school, routinely 80–90% of them raise their hands. A very small percentage of those same students compete in college athletics. They no longer engage in daily two-hour practices as they did in high school, so less physical activity means burning fewer calories.

Plus college can be hectic; many students hold part-time jobs and find  that college-level classes require more study time. Both scenarios can negatively affect their levels of physical activity.

So just how many pounds do college freshman gain that first year? A large review article published in the Journal of American College Health by Vella-Zarb and colleagues (2009) reports results from 24 studies that examined weight gain in college freshman. The authors concluded, “Weight gain occurs during freshman year, although the amount of weight gained tends to be much less than the ‘Freshman 15’ suggests. Typical weight gain is closer to 5 lbs. than to 15 lbs.”

I think it’s interesting to note that young adults 18–19 years old who don’t go to college gain about the same amount of weight as those who do attend college. So perhaps a general lifestyle change, rather than entering college, is responsible for weight gain in this young-adult population.

Vella-Zarb, R., and Elgar, F. The ‘Freshman 5’: A meta-analysis of weight gain in the freshman year of college. Journal of American College Health (2009), Vol 58, pp. 161-166.

True or False: You burn more calories when you drink ice-cold water?

Posted on June 4, 2018


Roughly 75%–80% of Americans are overweight or obese. It certainly is understandable that people would look for a variety of ways to burn extra calories and lose weight.

It is true that you burn more calories when you drink ice-cold water. The reason? Your body has to expend some energy (calories) raising the temperature of that water to bring it to the temperature of your body. However—and I’m really sorry that there is almost always a “however”—the number of additional calories we burn when we drink ice-cold water is very small and likely would not affect weight-loss efforts.

Think about it: If losing weight were as simple as consistently drinking ice-cold water throughout the day, we might actually be able to put a dent in today’s obesity rates.

Our bodies are composed of between 60% and 70% water. Were you aware that your brain is 90% water, your blood is 83% water, your muscle is 75% water, and your bones are 22% water?

Water is vital for health and necessary for most of our bodily functions. Water is important for creating saliva, protecting our organs, transporting and dissolving nutrients, regulating body temperature, lubricating our joints, circulating our blood, keeping our skin healthy, digesting and absorbing our food, and helping us fight illness.

Brown and colleagues (2006) studied water-induced thermogenesis (the number of calories we burn by drinking water) and whether the temperature of the water had an impact on calories burned. These authors concluded, “Drinking distilled water at room temperature did not increase energy expenditure. Cooling the water before drinking only stimulated a small thermogenic response, well below the theoretical energy cost of warming the water to body temperature. These results cast doubt on water as a thermogenic agent for the management of obesity.”

There is some credibility to the idea that drinking water before (or with) meals and replacing sugary drinks with water can significantly reduce your caloric consumption and aid in weight-loss efforts. But again, drinking lots of ice-cold water won’t result in burning a significant number of calories.

One final word of caution: Drinking ice-cold water can increase abdominal symptoms like diarrhea and cramping in some individuals with conditions such as irritable bowel syndrome.

Brown, C., Dulloo, A., and Montani, J. Water-induced thermogenesis reconsidered: The effects of osmolality and water temperature on energy expenditure after drinking. The Journal of Endocrinology & Metabolism (2006), Vol 91, pp. 3598-3602.

True or False: Many brands of bottled water are simply tap water?

Posted on March 19, 2018


Many people believe that bottled water is a healthier option than tap water. Marketers certainly take advantage of this; you often see commercials or print advertising campaigns for bottled water that depict snowy mountain peaks and clear, glistening springs or rivers. You see healthy, active people drinking bottled water while out riding their bikes or after going for a run.

Bottled water is big business. The worldwide market is estimated to be roughly $50 billion, with the United States accounting for $9 or $10 billion of those sales. The growth of bottled water sales in developed countries ranges from 5%–20% a year.

Drinking bottled water can be expensive. We pay roughly 5 cents per ounce for bottled water ($1 for a 20-ounce bottle), whereas we can drink a gallon of municipal water out of our tap for less than a penny.

I find it a bit ironic that I am writing this chapter in an airport, and I forgot to bring my water bottle! So I had to shell out $2 for a 20-ounce bottle of water. My goal is to refill that bottle at least 20 times on the trip to get my money’s worth.

All of those plastic water bottles can have a negative impact on the environment. According to estimates, approximately 80% of water bottles are not recycled, instead ending up in forests, lakes, streams and other inopportune places. That amounts to over a million tons of plastic-bottle waste per year.

And consider the significant environmental cost of the energy needed to produce all those plastic bottles as well as to transport and refrigerate the water.

Surveys show that the primary reasons people drink bottled water are a taste preference of bottled water compared to tap water and the belief that tap water is tainted with toxins or contaminants. The sale of bottled water in a particular city or region usually spikes following problems with a municipal water source, and sales in those areas can stay elevated for years. It’s hard to regain trust after an incident with a municipal water supply.

Plus drinking certain brands of bottled water is considered a status symbol—again, thanks to advertising.

I find it interesting that so many people automatically believe that bottled water tastes better than tap water. I’ve read about blind taste tests in large cities such as New York and Cincinnati where people actually prefer the  taste of tap water.

Estimates show that from 25%–60% of bottled water is simply tap water that has gone through some type of a purification process. That is exactly the case with the water I bought at the airport; it said “Purified” in large letters on the top, but I believe it was bottled in Atlanta, GA.

Van Hulle and colleagues (2012) conducted a study where they compared the chemical quality of bottled water and tap water and concluded that the main discriminating factor for tap water is the slightly increased chloride content. It was otherwise not possible to differentiate the tap water from the bottled water, indicating that the chemical composition is not statistically different.

I’ll admit that I do buy some bottled water, but I usually buy it by the case (for cost) and reuse a bottle as many times as I can once it has been opened. I have no hesitation about drinking water out of our home tap, and I can’t tell the difference between the taste of our tap water and bottled water.

Van Hulle, S., and Ciocci, M. Statistical evaluation and comparison of the chemical quality of bottled water and Flemish tap water. Desalination and Water Treatment (2012), Vol 40, pp. 183-193.

True or False: Gelatin is made by boiling the bones, skins, and hides of cows and pigs?

Posted on February 18, 2018


Gelatin simply is processed protein. It is similar to the structural protein collagen, a tough, fibrous protein found in connective tissue such as ligaments and tendons as well as in skin, bone and cartilage in humans and many animals. Collagen gives these structures strength and in some cases, elasticity, helping them stretch without tearing or ripping.

As hard as it may be to believe, commercial gelatin truly is made by boiling the bones, skins and hides of cows and pigs. Here’s how the Columbia Electronic Encyclopedia describes gelatin:

“Gelatin or animal jelly, foodstuff obtained from connective tissue (found in hoofs, bones, tendons, ligaments and cartilage) of vertebrate animals by the action of boiling water or dilute acid. It is largely composed of denatured collagen, a protein particularly rich in the amino acids proline and hydroxyproline. The process of manufacture is a complex one that involves removing foreign substances, boiling the material (usually in distilled water in alu- minum vessels to prevent contamination), and purifying it of all chemicals used in freeing the gelatin from the connective tissues. The final product in its purest form is brittle, transparent, colorless, tasteless, and odorless and has the distinguishing property of dissolving in hot water and congealing when cold.”

“Congealing” means to make thick or solidify, which is what happens when you make JELL-O. Most of us, either when we were children or as adults with our own children, have made JELL-O. The process is quite simple: Mix the JELL-O powder in a bowl with a cup of boiling water, add a cup of cold water, stir, and place in the fridge and wait. The waiting is the hard part for kids! JELL-O JIGGLERS® (you use only one cup of water and cut the chilled, firm JELL-O into shapes) are a huge hit with our three kids.

Making JELL-O or other gelatin brands is the most common use of gelatin. JELL-O was patented in 1845 by Peter Cooper, and I read recently that Kraft Foods sells over a million boxes of JELL-O a day! There is even a museum in Le Roy, N.Y., dedicated to JELL-O.

The first four JELL-O flavors were orange, lemon, strawberry and raspberry. There have been 36 flavors of JELL-O sold over the years; some of the flavors that didn’t last include apple, chocolate and coffee.

Gelatin is also used in cosmetics, shampoos, candy, photographic film and the coating on vitamins.

The process by which gelatin is made (boiling animal parts) may sound a bit disgusting to some, and it may on the surface appear to be unclean and not very safe. However, the steps are strictly regulated. The heating, treating and filtering process makes gelatin safe for consumption.

As you can imagine, many vegans avoid gelatin products because it originates from animal parts. If this is a concern for you and you’d like to be able to eat gelatin, there is a vegan version called agar that is derived from seaweed. Agar is also a good setting agent—we talked about gelatin’s congealing characteristic earlier in this chapter—and is commonly used throughout Asia in desserts. And some gelatin producers are starting to use more fish products to make gelatin.

I have to admit that prior to researching and writing this chapter, I had heard that gelatin was made from boiling the bones, skins and hides of animals, but I wasn’t certain it was true. Now that I know it is, I will think a bit differently about products with gelatin in them—but likely will still enjoy an occasional JELL-O JIGGLERS® with my kids.

Gelatin. Columbia Electronic Encyclopedia, 6th Edition; 11/1/2011, pp. 1. Columbia University Press.

True or False: Exercise after eating a meal causes food to be digested faster and fewer calories to be absorbed?

Posted on February 6, 2018


If you do a quick Internet search on this topic, it won’t take long to find recommendations to go for a walk after eating a meal. The rationale? The movement associated with walking will speed digestion and maybe even result in absorbing fewer calories.

One interesting statement I found on a website that advocates walking after eating suggests, “Getting a jump on digestion [by walking after a meal] will help continue that process through the night, burning more calories and shedding pounds faster.” This simply isn’t true.

Walking is a highly recommended form of physical activity because of its many health benefits. Walking can help us control our weight, increase our energy levels and good cholesterol, and decrease our risk for hypertension, cardiovascular disease, diabetes and stroke.

Walking has also been shown to help reduce our reliance on medications and improve our sex life. Walking is good! However, walking after eating a meal doesn’t speed up digestion, nor does it reduce the absorption of calories. This is a topic about which there appears to be a fair amount of disagreement in published literature. As stated by the author of one of the articles I reviewed, the impact of exercise on the time it takes food to pass through the gastrointestinal tract “is a matter of hard debate.”

Some research suggests that light aerobic exercise prolongs mouth-to-cecum (first part of the large intestine) transit time; some studies suggest that gastric emptying (time it takes for food to leave the stomach) doesn’t change with exercise; and some research suggests that transit time is accelerated with activity. The components and quantity of the meal and the type and intensity of the activity certainly could be factors as well.

Robertson and colleagues (1993) published a study in the Journal of Clinical Gastroenterology that examined the effects of exercise on total and segmental colon transit. Their results showed that with exercise, total gastrointestinal transit time decreased in five subjects, increased in six subjects, and did not change in five subjects. They concluded, “These observations support our previous findings that physical activity to the extent that average people consider routine exercise does not necessarily improve gastrointestinal transit.”

There isn’t anything wrong with walking after eating; my wife and I often walk after dinner, and that certainly is healthier than sitting and watching television, which many people do after the evening meal. However, we don’t walk in the evenings because we think it will help digest our food or result in fewer calories being absorbed; we simply walk because we enjoy it!

Some people can experience gastrointestinal distress if they walk right after eating, so you may want to wait 20 or 30 minutes before sliding into your walking shoes and hitting the streets or the nearest walking trail.

Robertson, G., Meshkinpour, H., Vandenberg, K., James, K., Cohen, A., and Wilson, E. Effects of exercise on total and segmental colon transit. Journal of Clinical Gastroenterology    (1993), Vol 16, pp. 300-303.