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'On the Web' is an internet-based supplement that provides additional web content to supplement the material in Concepts of Fitness and Wellness. Browse through the whole document to explore web content related to this concept. If you know the specific 'On the Web' number or page number of the web icon in the text you can click on the direct link you are looking for below. Click here to access the other Online Learning Center resources available from the McGraw-Hill Website (http://www.mhhe.com/corbin7e). The material available here is for the exclusive use of students and instructors using the Concepts-based textbooks. All rights reserved (McGraw-Hill Higher Education). Web 15-01 – Physical Activity and NEAT Web15-02: Dietary Restraint and Appetite Suppressants Web15-03: Problems with Fad Diets Web15-05: Prescription Medicines Web15-06: Artificial Sweeteners and Fat Substitutes Web15-07: Risks Associated with Ephedra Web15-09: Supplemental Readings Visit FatFoe, the Federal Trade Commission's teaser site about bogus weight loss claims. Learn how to spot the seven claims that almost always signal a diet rip-off.  Web 15-01 – Physical Activity and NEATThe benefits of physical activity for weight control are well established but many in the population still find it difficult to obtain the needed amount of activity for good health and for weight maintenance. Researchers at the Mayo Clinic (led by Dr. Jim Levine) have been working on ways to re-engineer activity into typical activities of daily living, calling these activities Non-Exercise Activity Thermogenesis (NEAT). To test some of their ideas, Dr. Levine developed a mobile workstation that allows him to walk on a treadmill at very slow speeds (~.5-1.0 mph) while working on a computer and answering his phone. The adaptation allows him to expend far more calories per day than if he were sitting at his desk. The visibility from this project has helped to increase awareness about the importance of small amounts of activity in the day. To expand the concept, his group established a partnership with local schools to test the potential value of a similar, active form of schooling for youth. Read more about Dr. Levine's research and learn more about his workstation at: http://cancercenter.mayo.edu/mayo/research/levine_lab/ Reference for Dr. Levine's work: Levine, JA, Lanningham-Foster, LM, McCrady, SK, Krizan, AC, Olson, LR, et al. Interindividual variation in posture allocation: possible role in human obesity. Science. 2005 Jan 28;307(5709):584-6. Kotz, CM, and Levine, JA. Role of non exercise activity thermogenesis (NEAT) in obesity. Levine, JA, and Kotz, CM. NEAT—non-exercise activity thermogenesis—egocentric & geocentric environmental factors vs. biological regulation. Acta Physiol Scand. 2005 Aug;184(4):309-18. Levine, JA. Non-exercise activity thermogenesis (NEAT). Nutr Rev. 2004 Jul;62(7 Pt 2):S82-97. Web15-02: Dietary Restraint and Appetite SuppressantsMost Americans know what they should eat but still find it hard to restrain themselves when exposed to so many sources of high calorie/high fat foods in restaurants and food stores The Center for Science in the Public Interest (CSPI - http://www.cspinet.org) provides valuable information for consumers about how to better understand food labels and make good decisions about food products. They recently published a highly successful book called The Restaurant Confidential (http://www.cspinet.org/restaurant/) that helps consumers better understand restaurant foods. The Nutrition Action Health Letter published by the CSPI provides useful information about other commercially available foods (http://www.cspinet.org/nah/index.htm). An interesting interactive activity to test your knowledge of restaurant foods is their Rate Your Restaurant Diet quiz (http://www.cspinet.org/nah/quiz/index.html). Take the diet quiz at the following web site and then click the button at the end to see how you scored. To help curb their appetite, many Americans have begun to rely on prescription medications. These medications are commonly advertised in magazines and television to encourage American's to ask their doctors for prescriptions. A report in the New England Journal of Medicine (Vol. 337, No. 9, Aug. 28, 1997) suggested that the use of fenfluramine/phentermine (fen/phen) could lead to a form of valvular heart disease. Two products containing these drugs – Redux (dexfenfluramine hydrochloride) and Pondimin (fenfluramine hydrochloride) have been taken off the market but new products have been developed that have similar properties. The FDA has recently approved the use of a product called Meridia that contains a drug called Sibutramine. Like these other drugs/products, Meridia reduces a person's appetite by altering levels of a hormone in the body (serotonin) that makes people feel full. Reports have indicated that it can raise blood pressure and lead some people to have irregular heart beats. Studies haven't documented any specific harmful effects to this point but the AHA currently cautions consumers to consult their physician and consider the relative benefits and risks before using it. Click here to see the American Heart Association recommendation on Dietary/Weight Loss Supplements. The American Dietetic Association also has a Fact Sheet on weight loss to educate consumers about whether weight loss is appropriate for them. A major challenge in dietary restraint is in the lack of awareness of appropriate portion sizes. Many restaurants provide excessive amounts of food to consumers and this has led to confusion about the appropriate portion sizes. Click here to see resources from the National Institutes of Health aimed at preventing portion distortion. Web15-03: Problems with Fad DietsThere are a number of fad diets that are readily available to consumers. Most are popularized through the publication of books along with promotional tours, talk show appearances and direct advertising. Many consumers buy into these diets possibly because it gives them new hope to combat their long-term struggles with weight control. Unfortunately, the efficacy of these diets is not well supported in the scientific literature. Most of these fad diets take a small fact about the diet or the bodies' metabolic processes and intentionally misapply it to influence consumers. They seek to create the illusion that they have discovered some new explanation for obesity that the medical and scientific communities overlooked. This is not a very likely scenario considering the breadth of research that is conducted in nutrition and the major public health issues associated with obesity. Consumers should rest assured that if there was an easy and safe way to help people lose weight it would be made readily available to them and not available through one specific paperback book. The premise for some of the popular commercially available fad diets is described below to facilitate awareness of these different diets. Individuals considering any fad diet should educate themselves about the truth behind some of these diets instead of being swayed by what they hear being advertised on TV and in magazines. The Sugar Busters Diet is a low carbohydrate diet that advocates the consumption of protein, fat and only certain low "glycemic-index" carbohydrates such as vegetables and fruits. They claim that the consumption of refined sugar speeds increases insulin secretion and causes increased appetite and fat storage. While reducing refined sugars is a reasonable recommendation, the consumption of excess sugar is not likely to lead to weight gain unless caloric intake is also high. Without a reasonable amount of carbohydrates in the diet, the protein content becomes too high and is harmful on the kidneys. The diet also makes other unsubstantiated claims such as the belief that drinking beverages with a meal leads to inadequate chewing and dilution of digestive juices. Like other fad diets, the Sugar Busters Diet takes a few small truths about the diet (e.g. carbohydrates lead to insulin release) and imply that it is the source of all dietary problems. The Zone Diet takes the low-carbohydrate hype to the extreme by implying that there is an optimal dietary balance that promotes desirable "eicosanoid levels" and control over the bodies hormonal and metabolic systems. Eicosonoids are hormones that regulate immune function, inflammation and blood clotting and may be involved in heart disease but there is no evidence that increased levels of insulin leads to increased eicosonoid levels. The diet recommends mono-unsaturated fats, and an overall 40% carbohydrate, 30% protein and 30% fat distribution. The reduction in saturated fats is a good dietary goal but the switch to a protein-based diet is not consistent with other dietary recommendations. Like the Atkins Diet and the Sugar Busters diet, the reduction in carbohydrates leads to some weight loss due to water excretion but this is of no clinical or health relevance. Like other diets, the weight loss that does result are mainly due to the caloric restriction recommended in the diet. Eating the recommended 1800 calories a day will lead to some weight loss but it is not due to the specific foods that are eaten but rather due to the lower intake of calories. There are a number of other excellent resources and reports that provide the facts about high protein diets. Consumers (and students) should consult these sites before believing many of the commercial sites that have an economic incentive for promoting the Atkins products.
The Center for Science in the Public Interest (www.cspinet.org) publishes The Nutrition Action Healthletter (a scientifically based review of food and nutrition topics) to help consumers make sense of all the claims that they hear about regarding different diets. You can download the pdf files from the newsletters from the website. http://www.cspinet.org/nah/11_02/bigfatlies.pdf . This article describes the misinformation that exists about popular high fat diets such as the Atkins diet and describes the health consequences associated with long term use of these diets. Weighing the Diet Books: http://www.cspinet.org/nah/01_04/cover.pdf This article compares some of the recent information on the different diets. While it criticizes most of the high protein diets that are currently available, it did suggest that the South Beach Diet makes the most sense and is easiest for consumers to follow. Incessant efforts to lose weight through dieting also can have a number of negative consequences. The National Eating Disorders Association (http://www.nationaleatingdisorders.org/p.asp?WebPage_ID=337) cites a number of factors that might make you consider NOT dieting. Web15-04: The Atkins DietThe Atkins diet has captured the public's imagination (possibly because it allows people to eat high fat foods that most people enjoy). Many food products and restaurants now feature "Atkins friendly" foods. While the Atkins diet is getting considerable visibility in commercials it doesn't necessarily mean that it is safe or effective. A recent study in JAMA provides clear evidence of some harmful changes in lipid levels that result from regular use of the Atkins diet. A non-profit agency called Physicians Committee for Responsible Medicine (PCRM) has created a web page called the Atkins Diet Alert (http://www.atkinsdietalert.org/)that provides an accurate scientific analysis of the Atkins diet and clearly points out the problems with the Atkins diet. Dr. Atkins New Diet Revolution: According to the Atkin's diet, carbohydrates are the main cause of obesity. The program recommends that people avoid such staple foods as breads, pasta, most fruits and vegetables, milk and yogurt and instead emphasize meat, fish, poultry, eggs, cheese and butter. In phase I of the diet (2 weeks), users are supposed to restrict carbohydrates to 20 grams per day and total calories to 1400 kcal/day. This is intended to "correct metabolic imbalances". In the final phase, the diet allows 25-90g of carbohydrate and up to 1800 kcal/day. The premise for the diet is that obesity is usually associated with high levels of insulin - because carbohydrates cause the release of insulin they erroneously conclude that they are the cause of obesity and should be avoided. The link between obesity and insulin resistance is true but the insulin response is a consequence of obesity and not a cause of obesity. Another premise in the Atkins diet is that dietary ketosis is a desirable metabolic state that helps people lose weight. The fact is, ketosis is the bodies' inefficient way of producing energy from a largely protein-based diet. It is a process that normally occurs in cases of starvation where the body begins to break down protein for energy. The extra protein in the diet leads a person into a state of ketosis but this can be very harmful to the kidneys. The main reason that people report losing weight with the Atkins diet is that with less carbohydrate in the body, there is increased sodium excretion in the kidneys and therefore large amounts of water loss. As the body adjusts to the water loss, weight loss ceases. The Atkins diet is not an effective long term solution for weight control and is counter to the well established nutritional guidelines supporting fruit and vegetable consumption and recommending lower saturated fat intakes. Web15-05: Prescription MedicinesSome people today are turning to prescription medications for weight loss. The Weight Control Information Network provides valuable information when considering prescriptions as a method of weight loss. According to this website, the FDA has currently approved 2 prescription drugs for long term use and 3 for short term use with weight loss. Generally these drugs are only prescribed for those who have a BMI greater than 30 or for those at high risk with a BMI greater than 27. Patients that are considering the use of prescription medication for weight loss should consider the following potential risks associated with these drugs:
Several other sites offer useful information on prescription drugs and weight loss: Web15-06: Artificial Sweeteners and Fat SubstitutesFood science has led to the development of a number of artificial sweeteners and fat substitutes. The American Dietetics Association (ADA) has posted a position statement on the safety and implications of these food additives ('Use of nutritive and nonnutritive sweeteners - Position of ADA'. J Am Diet Assoc. 1998;98:580-587). The ADA document categorizes sweeteners into "nutritive" and "nonnutritive" categories to acknowledge differences in the amount of energy provided by the types of sweeteners. Nutritive sweeteners include sugar sweeteners (eg, refined sugars, high fructose corn syrup, crystalline fructose, glucose, dextrose, corn sweeteners, honey, lactose, maltose, various syrups, invert sugars, concentrated fruit juice) and reduced-energy polyols or sugar alcohols (eg, sorbitol, mannitol, xylitol, isomalt, and hydrogenated starch hydrolysates). Nonnutritive sweeteners (eg, saccharin, aspartame, acesulfame-K, and sucralose) provide no energy in the form of calories. They are generally considered to be "high intensity sweeteners" because they are highly concentrated and sweeten foods with little volume added. Polyols and nonnutritive sweeteners can both replace sugar sweeteners and are therefore termed macronutrient substitutes, sugar substitutes, sugar replacers, or alternative sweeteners. The ADA report also specifies the safety of different sweetening agents. Most nutritive sweeteners are considered as "Generally Recognized As Safe" (GRAS) and others are considered food additives. The U.S. Food and Drug Administration (FDA) has approved 4 nonnutritive sweeteners and these are regulated as food additives: saccharin (pending additional study), aspartame, acesulfame potassium (or acesulfame-K), and sucralose. See a summary of the different sugar substitutes below.
While the use of some of these products may help some individuals, they are certainly not a panacea that can solve our societies' poor eating habits. There is some evidence that regular use will not lead to significant decreases in the consumption of either sugar or calories. In fact, there is some evidence that the use of these engineered foods can actually lead to undesired changes in dietary patterns. For example, it has been documented that there has been a 3-fold increase in the per capita consumption of artificial sweeteners (e.g. saccharin, aspartame) since 1965. If these products were having a positive impact on calorie intake, one would expect to observe corresponding declines in the consumption of sugar. However, during this same time frame there has been a 14% increase in the consumption of sugar. Thus, the increased use of artificial sweeteners has only increased most American's preference for sweet foods. Americans currently consumer over 50% of the world's use of nonnutritive sweeteners. While sweets can be a healthy part of the diet, excess amounts can contribute to weight gain, and other health problems. Click here to read the American Heart Association recommendation on fat substitutes Web15-07: Risks Associated with EphedraEphedra is a popular weight loss supplement found in many over the counter products (e.g. Xtreme Lean. Trim Fast. Metabolife 356). Because ephedra (also known as Ma Huang) is considered to be an herbal stimulant many consumers erroneously assume that it is safe . When combined with caffeine, ephedra acts like amphetamines, or "speed and can be very dangerous (even leading to death). The recent death of baseball player Steve Bechler (Feb 2003) has been attributed by some to be due to ephedra products (a bottle of Xenadrine RFA-1, an over-the-counter weight-loss product containing ephedra, was found in Bechler's locker after he collapsed). Bottles of ephedra containing products typically contain a warning label saying the consumer should consult a doctor before using it but most consumers ignore this warning. Over the past few years, the harmful effects of ephedra have become sufficiently documented in the scientific literature. Results from a study commissioned by the National Institute of Health (NIH) firmly concluded that "dietary supplements containing ephedra may present significant or unreasonable risks". Click here to see a summary of the report or here to access the full report. Based on this accumulated evidence, the Food and Drug Administration (FDA) acted to completely ban the use of ephedra in supplements. Read more on the banning of ephedra products by the FDA This is the first actual case in which a supplement was banned through the procedures outlined in the Dietary Health and Supplement Act of 1994. While the title of the act implies some degree of protection for consumers it actually provides more loopholes for companies to release untested and potentially harmful products into the marketplace. The Act essentially puts the burden of proof on the FDA to document the risks associated with a particular supplement rather than on a supplement company to prove that a product is safe. The long delay in getting ephedra banned should be a reminder to consumers that just because a product is sold on shelves in stores you cannot necessarily assume that it is safe. Contact the FDA at 800 FDA-1088 to report adverse health effects from any dietary supplements. Also visit the FDA website at www.fda.gov/medwatch. Web 15-08 – Web ResourcesAmerican Dietetic Association - www.eatright.org Berkeley Nutrition Services - www.nutritionquest.com Center for Science in the Public Interest - www.cspinet.org Fast Food Facts: Interactive Food Finder - http://www.ahealthyme.com Meals Online - www.meals.com Office of Dietary Supplements - http://dietary-supplements.info.nih.gov/ USDA Food and Nutrition Information Center - http://www.nal.usda.gov/fnic/ Web15-09: Supplemental ReadingsReferences new to 7e/14e:
References from Past Editions:
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