If weight management is a goal of yours for the New Year, it may be helpful to review the basic components of the energy balance equation. The most common unit of energy measurement in the field of nutrition is called the Calorie or kilocalorie (kcal). Lasting changes in body weight are determined by the number of kcal “in” vs. kcal “out”.
The energy intake side of the equation consists of four major components: carbohydrates, lipids, proteins, and alcohol. Carbohydrates in the form of sugar and starch contain 4 kcal/gram. Lipids from animal fats and vegetable oils contain 9 kcal/gram. Proteins from meat or beans contain 4 kcal/gram. And alcohol in beer and wine contains 7 kcal/gram. Water, vitamins, and minerals do not contain energy (0 kcal/gram). All told, the average American consumes between 1800-2700kcal/day (Source: USDA, 2010).
Although energy intake seems simple and straightforward, there are some “peculiarities” to consider. For instance, fiber is a type of carbohydrate that our bodies cannot digest and therefore does not contain kilocalories (for the most part). Also, while fats and oils are very energy dense (9kcal/gram), they are slow to digest and contribute to a greater sense of satiety than sugar or starch. That means that lipids help keep us fuller longer, and may help prevent cravings in between meals.
The energy expenditure side of the equation consists of three major components: resting metabolic rate (RMR), the thermic effect of food (TEF), and physical activity (PA). RMR is the number of kcal expended at rest and is largely determined by a person’s lean muscle and organ mass. TEF refers to the number of kcals that a person expends to digest and absorb food. PA refers to the number of kcal expended above and beyond RMR and TEF; it can vary from several hundred kcal/day to several thousand kcal/day. For a moderately active person, total daily energy expenditure (RMR + TEF + PA) may range from 1500kcal to 2500kcal.
Calories and weight management
With regard to weight management there are approximately 3500kcal per pound of body fat – although the exact number of kcal in a pound body fat varies significantly between people (see previous posts). Thus, if you would like to lose one pound of body fat you’ll need to create a deficit of 3500kcal. Despite the quickness and ease with which diet books and advertisements claim to create this deficit, hopefully you know better. Consider for one that a 150lb person expends approximately 100kcal to walk or run a mile and you’ll realize that losing/maintaining weight takes considerable focus and effort. It certainly can’t happen overnight!
Food for thought
Next week we’ll discuss the most common pitfalls or mistakes that people make when attempting to lose weight. In the meantime, what do you think the three most common pitfalls are?
Fluoridation of Public Water Supplies: Effective Health Promoting Strategy or Unwelcome Mass Medication?
Tooth decay (or dental caries) represents one of the most significant diseases worldwide, effecting over 2 billion individuals. In 2006 in the U.S., dental caries was considered the most common chronic childhood disease (Oral Health – Healthy People). A large percentage of adults in the U.S. over the age of 50 years also have dental decay. Given the large number of affected individuals and the fact that there is no way to “regrow” damaged teeth, it comes as little surprise that preventative strategies have been developed. First and foremost has been the use of fluoride, which helps prevent dental caries. It is the active ingredient in toothpaste. Moreover, fluoride is routinely added to public water supplies in many locales across the world. This sounds like a good thing, right? It actually depends upon whom you ask. The fluoridation of public water supplies has generated much controversy over the past few decades. Let’s take a closer look at the pros and cons of fluoridation of water, and see who is for and who is against it.
Water fluoridation began in the 1940s, and controversy has swirled since this time. Proponents argue, and scientific data has since proven (Systematic Review of Water Fluoridation), that fluoridation of public water supplies decreases the burden of tooth decay. Although with significant variance, scientific studies consistently show that water fluoridation decreases cavities in children (18-60% reduction). Opponents, however, argue against it for several reasons: 1) excess fluoride intake can cause serious health problems; 2) the outcomes do not justify the cost; and 3) the dosage cannot be properly controlled. In regards to point 1, there is little scientific evidence that water fluoridation causes any adverse health consequences except dental fluorosis, which is a harmless discoloration of the teeth. Point 2 is more of a philosophical stance that is clearly a matter of opinion. In reference to point 3, if properly managed, water fluoridation can be maintained at a level that promotes dental health and minimizes adverse health risks. Opponents argue that too much fluoride could cause cancer, but scientific data do not support this argument (NHMRC Public Statement: Efficacy and Safety of Fluoridation).
So, who argues for and who argues against water fluoridation? Those against it include the International Chiropractor’s Association who argue it is “possibly harmful and deprivation of the rights of citizens to be free from unwelcome mass medication”. The Sierra Club in the U.S, the Canadian Green Party and some notable scientists have also come out in opposition to water fluoridation. Those in favor include the U.S. Centers for Disease Control (CDC), the American Dental Association, Health Canada and the World Health Organization (WHO).
You now have the basic scientific facts. Who do you agree with on this issue? Will you continue to drink fluoridated water? What about bottled or filtered water, do they contain fluoride? The answer is probably no. Whatever you decide, just know that leading scientific organizations worldwide support water fluoridation and feel that these programs are among the most significant health advances of the 20th century.
Welcome to part two of a discussion about issues related to body weight. Last week we addressed the concept of “nature” – that our body weight is genetically predetermined and biologically controlled. While there is strong evidence in favor of nature, genes are not the only determinant of body weight. If that were the case, the United States would not have experienced such a rapid rise in obesity rates over the past few decades, nor would we see such a strong geographic relationship associated with obesity. This is where “nurture” factors enter the picture.
Nurture factors include the environment in which we are raised and the behaviors that we are taught or engage in. Take a look at the map provided by the Centers for Disease and Control in the previous post. Notice any geographic trends associated with obesity? The lowest rates of obesity are found in the Rocky Mountain region. The highest rates of obesity are found in the Midwest and Southeast. What environmental and/or social factors could explain these phenomena?
It could be any number of things. A partial list of nurture factors includes altitude, terrain, climate, food culture, activity culture, access to healthy food, prevalence of fast food restaurants or vending machines in schools, urban vs. rural lifestyles, crime rates, bike lanes, access to gyms and recreation facilities, parks and open space, etc. The strongest nurture factor related to obesity is socioeconomic status (SES), which is comprised of a person’s or population’s occupation, education, and income level.
Sociologists often use SES as a means of predicting behavior. In the case of overweight and obesity, a lower SES may be associated with behaviors like overeating and/or physical inactivity. However, it’s important to understand that adoption of these behaviors is often by need, not by choice. For instance, if a person works multiple jobs to make ends meet, they are less likely to have time to exercise or prepare their own food. They are also less likely to be able to afford running shoes or gym memberships. And, ironically, food that costs less is often higher in calories, fat, and sugar.
Food for thought
Next week we’ll start to look at what a person can do to maintain a healthy body weight or lose weight if necessary. But before we dive into the “ins and outs” of dieting, I wanted you to understand just how complicated and individualized body weight is. We all have different genes, live in different geographic regions, have different food and activity cultures, and come from different socioeconomic statuses. Take a moment to assess the factors that determine your body weight. Also take a moment to acknowledge that some people are more prone to weight gain than others (from both a nature and nurture perspective), and understand that what works for one person may not work for another.
With New Year’s eve fast approaching, I thought it might be a good time to address some issues related to body weight. After all, nearly half of New Year’s resolutions will involve weight loss, and most will fail (US News and World Report). My intention is to provide you with some good “food for thought” and, ultimately, some realistic and achievable resolutions related to body weight.
State of the Union
As you may already know, the United States has what’s called an obesity “epidemic”. According to the Centers for Disease Control, fully two thirds of Americans are considered overweight or obese (see figure below for data on individual states). The good news is that obesity rates have largely leveled off in recent years. The bad news is that negative health and social consequences associated with overweight and obesity continue to plague the majority of Americans.
To the uniformed, overweight and obesity appear to be caused by simply eating too much and/or not exercising enough. However, no biological system or phenomenon is that simple. There are myriad factors that contribute to high rates of overweight and obesity in the United States. Some of these factors are controllable, others are not.
Nature vs. nurture
Let’s first address factors that are, for the most part, uncontrollable. These factors include our genes (a.k.a. “nature”) and the social environment in which we live (a.k.a. “ nurture”).
Do genes cause obesity? The short answer is no – it’s not that simple! But there is strong evidence that genes make some people more prone to weight gain than others. For example, the Pima Indians of southern Arizona have been identified as having a genetic “thrifty metabolism”, which causes them to burn fewer calories than people with “normal” metabolic rates. It just so happens that the Pima Indians also have the highest rates of obesity and Type 2 Diabetes in America.
However, if obesity was solely or centrally linked to our genes, then why the sudden rise in American obesity rates? Our genes evolved over thousands of years, but the U.S. obesity epidemic sprang up in only 20-30 years. While genes may play a role in overweight and obesity, “nurture” factors are much more likely to blame for the current state of affairs.
Food for thought
Next week’s blog post will explore nurture factors related to overweight and obesity in the United States. In the meantime, can you think of ten specific nurture factors on your own? What social and/or environmental factors have changed over the past few decades that may have contributed to the rise in overweight and obesity? What social and/or environmental factors differ among states with the lowest rates of obesity (e.g., Colorado) vs. states with highest rates of obesity (e.g., Mississippi)?
Centers for Disease Control website for “Overweight and Obesity”. Accessed December 15th, 2013: www.cdc.gov/obesity/data/
US News and World Report. Accessed December 15th, 2013: http://health.usnews.com/health-news/blogs/eat-run/2013/12/13/how-to-make-realistic-new-years-resolutions
In 1970, sucrose was the main food and beverage sweetener used in the U.S. Sucrose, or “table sugar”, is composed of one glucose molecule linked to a molecule of fructose. In 1970, ~15% of America were obese. Today, obesity rates are around 35% and high fructose corn syrup (HFCS) has replaced sucrose in many foods and drinks. The question that has caught the attention of many over the past several years then is: What is the association between this dramatic increase in the consumption of HFCS and the skyrocketing obesity rates in the U.S. Let’s take a closer look at this issue and see what the peer-reviewed scientific literature has to say.
Why has HFCS replaced sucrose in many foods and drinks? That’s an interesting question, but first lets’ consider the source of HFCS. It is made by extracting starch from corn, and then treating the starch to release the glucose, followed by a procedure which converts about half of the glucose to fructose. HFCS is cheaper and more stable during storage than sucrose, explaining why food manufacturers prefer to use it as a sweetener.
Studies performed in the past decade suggested that there was a direct link between increased HFCS intake and obesity. This made sense since fructose is more easily converted to fat than glucose and it may alter hormonal signals that control feeding behavior differently from glucose. Again, interesting facts, but how is the sugar content of HFCS really different from sucrose? The answer is not very different, in fact, very similar. Sucrose is 50% glucose and 50% fructose, while HFCS contains either 55% fructose/42% glucose (in sodas) or 42% fructose/ 53% glucose (used in baked goods). So as you can see, the composition of HCFS and sucrose is very similar. Why then would HFCS lead to different health consequences as compared to consumption of sucrose? The answer is that it probably does not.
A survey of the scientific literature identifies several very recent papers that conclude that from a nutritional or health-related perspective, consuming sucrose versus HFCS is not different. One recent study found that HFCS and sucrose do not differentially affect levels of “energy-regulating hormones” in humans ( Nutr. Res., 2013). Another paper in the International Journal of Obesity concluded that there was a lack of evidence to link HFCS consumption with the current obesity epidemic (Int. J. Obes., 2013). It was also noted that there was inconclusive evidence to link HFCS to childhood obesity (Ped. Obes., 2013). The consensus on this issue thus seems to be shifting.
Nutrition science tells us that greater energy in than energy out leads to weight gain over time. Not only has HFCS intake increased over the past few decades, but total energy intake has as well. Perhaps the culprit is not HFCS, but rather a change in the typical American’s lifestyle towards more food intake and less activity. Future studies will undoubtedly address this important issue further, but in the meantime, will you avoid food and beverages sweetened with HFCS? How do you think it could positively influence your health if you switched to sucrose sweetened foods and drinks? Or maybe the best approach is to decrease intake of ALL sugar sweetened foods and decrease overall energy intake in that way. What will be your approach?
Foodborne illness is something that most people don’t think about until they get it themselves. However, 1 in 6 Americans (48 million people) get sick from and 3,000 die each year due to foodborne illness (Centers for Disease Control, CDC). Given that the holiday season is in full swing, with Thanksgiving turkeys and Christmas hams taking center stage, there’s no better time for a primer on foodborne illness.
What is it?
Foodborne illness (or food poisoning) is the general name for illness caused by more than 250 different pathogens. These pathogens include bacteria, viruses, parasites, or toxic chemicals found on fruits, vegetables, meats, and cooking surfaces. The pathogens enter the body through the gastrointestinal tract and may cause nausea, vomiting, abdominal cramps, fever, diarrhea, and dehydration. Death is also possible if symptoms persist.
What can you do?
The CDC and FightBac.org suggest a number of consumer safety precautions to avoid foodborne illness. The major precautions include cleaning, separating, cooking, and chilling. Should you still be unfortunate enough to contract a foodborne illness, don’t hesitate to report your symptoms to your local health department.
- CLEAN: Wash yourself and your produce.
- Wash your hands with warm water and soap for at least 20 seconds before and after handling food, using the bathroom, changing diapers, or handling pets.
- Rinse fresh fruits and vegetables in running tap water to remove visible dirt and grime.
- SEPARATE: Don’t cross-contaminate.
- Use one cutting board for fresh produce and another cutting board for raw meat, poultry and seafood.
- Never place cooked food on a plate that previously held raw meat, poultry, seafood or eggs.
- COOK: Use a food thermometer with meat, poultry, and fish to ensure that proper internal temperatures are reached.
- Cook roasts and steaks to a minimum of 145°F, poultry to a minimum of 165°F, and fish to a minimum of 145°F or until the flesh is opaque and separates easily with a fork.
- CHILL: Refrigerate leftovers promptly.
- Refrigerate leftover foods if they are not going to be eaten within 4 hours.
- Large volumes of food will cool more quickly if they are divided into several shallow containers for refrigeration.
- REPORT: Report suspected foodborne illnesses to your local health department.
- Often calls from concerned citizens are how outbreaks are first detected.
- Your cooperation may be needed even if you are not ill.
Food for thought
Have you or someone you know suffered from a foodborne illness? If so, did you report the incident to your local health department? What precautions should consumers take while preparing meats, fruits, and vegetables? What internal temperatures should you cook meat in order to avoid foodborne illness?
CDC Food Safety website: http://www.cdc.gov/foodsafety/cdc-and-food-safety.html
Fight Bac website: http://www.fightbac.org