The Obesity Epidemic

 

The Obesity Epidemic

The growing prevalence of obesity is a major health problem across the globe. Countries previously facing food shortages and underweight are now experiencing increasing overweight. Current food and lifestyle patterns have influenced obesity statistics across the U.S. (Figure 1-1). In 2000, no state had an obesity prevalence of 30% or more; by 2010, 12 states had reached this level.2 Seventy-four percent of men and 64% of women are overweight or obese,3 and 32% of children aged 2 and over are either overweight or at risk for becoming overweight.4 Among men, overweight or obesity is more likely to occur in middle age (ages 40 to 59); among women it is more common in older age (over age 60).3 Children over the age of 5 are at greater risk of being overweight than preschoolers. The rise in type 2 diabetes has paralleled the rise in obesity, such that 20.9 million people have been diagnosed, more than triple the number in 1990, and it is estimated that another 7 million are undiagnosed. However, the good news is that body weight appears to be leveling off in both children and adults. Our environment, which promotes the consumption of energy-dense foods while providing limited need or opportunity for energy expenditure, has been referred to as “obesogenic,” and contributes to the obesity problem.7,8 In contrast to earlier times when humans survived as “hunter-gatherers,” we now have a plentiful supply of good-tasting, high-calorie food, with little physical activity required to obtain it. The ever-present vending machine, special offers of two hamburgers for the price of one, and accessible food at all sporting and most social events all contribute to excessive food intake . Portions served at fast-food restaurants are two to five times larger than those offered 20 years ago, and food served at home often equals three to four times the serving size referred to in meal planning guides Most people increase their energy intake when more food is served, adding to the potential for overeating at “all you can eat” food outlets. As energy intake has risen, energy expenditure has dropped. For many children, television or video games have replaced active outdoor games, and they ride rather than walk to school. Rural localities and new residential developments lack sidewalks, and many neighborhoods are unsafe for walking. Collaborative efforts among government agencies

How Did Our Food Patterns Become So Diverse

the eating patterns and favorite foods of various racial, ethnic, and cultural groups if they are to help these families develop meal plans that will be accepted and implemented.13 Working with diverse groups can require language training. About one in five families in the U.S. speak a language other than English at home; within this group, over half speak Spanish. The Focus on Culture box, “How Did Our Food Patterns Become So Diverse?” introduces factors influencing food patterns. Appendix D “Cultural Dietary Patterns and Religious Dietary Practices” will help begin your study of cultural and ethnic foods.

New Products in the Marketplace

 Researchers have found that various foods contain naturally occurring substances other than nutrients that promote health. These foods are known as functional foods. Phytochemicals (plant chemicals) found in fruits, vegetables, and whole grains appear to have cancer-fighting properties. Dark chocolate, often considered a food to be avoided, is now known to contain flavonoids, phytochemicals that help to control blood pressure. Public interest in nutrients and other substances believed to influence health has prompted the food industry to develop new foods that meet this demand. Plant sterols that help lower blood cholesterol levels are being added to margarine; orange juice has become an alternative source of calcium and vitamin D to prevent bone loss. Conversely, “energy drinks” with added herbs and stimulants are being marketed to replace water or other healthy beverages. As more products claiming health benefits enter the marketplace, the task of helping consumers make appropriate choices will fall to the health professional. 

Nutrition Misinformation

Consumer surveys indicate that the majority of Americans (91%) believe they have some control over their health, and 72% believe that food and nutrition play the greatest role.However, 75% of consumers rely on media outlets including the Internet as their major sources of health and nutrition information, and only half use medical sources. A Google search for “nutrition listservs” yielded over 100,000 sites, but it is likely that many of these writings are not reviewed by nutrition experts. Internet sites marketing herbs, drugs, and health devices are not monitored by government regulatory agencies and often contain misleading information. Reputable food companies provide helpful facts about the nutrient content of their products, but commercial sites devoted to sales often post misleading health claims. Internet sites maintained by government agencies, universities, state extension services, and medical facilities provide evidence based information and should be the first source for public information on foods, nutrition, and health. At the close of each chapter in this text is a list of recommended websites for consumers or health professionals seeking additional information.

Genes in Nutrition and Health

The Human Genome Project, an international project to map the human genetic code, is helping scientists learn how diet and the environment influence our genes (nutrigenomics), and how these interactions influence our survival. The study of nutrigenetics concentrates on how even slight variations in our genetic code affect our nutrient needs, susceptibility to particular diseases, and response to our environment. A gene is a DNA sequence that can be translated into a protein, and bioactive components in food influence its expression. Nutrients such as essential fatty acids and vitamin A are bioactive; phytochemicals also act in this way. Individuals with different genes react differently to particular phytochemicals, and while an increased intake can have a positive effect on one person, it may not benefit another. This likely contributes to why research studies looking at nutrient requirements have different results, as particular individuals will differ in their requirement for a specific nutrient. Gene– nutrient interactions also influence response to nutritional interventions. For individuals with a specific genetic alteration, changes in the amounts and types of dietary fat may effectively lower their elevated blood LDL (low-density lipoprotein) cholesterol, but for others the intervention will have no biological effect. The study of nutrigenetics can help us learn why certain people cannot produce the enzyme lactase needed to break down the lactose in milk, or why individuals with celiac disease have an immune response to certain proteins in wheat flour. The study of nutrigenomics will help us understand how particular substances in functional foods, such as tomatoes or green tea, influence various chronic diseases. In the future, a young man may seek information from a genetic screening service about variations in his genetic code that will increase his risk of chronic disease and then take this report to his health professional who will use computer software to generate personalized dietary advice to help avoid these conditions.21 Currently, we are able to make general recommendations regarding disease prevention for individuals whose family history or medical diagnoses put them at risk, but we still have a lot to learn before we can prepare individualized diets based on one’s genetic code. Consumers should avoid commercial companies that offer genetic screening and are not associated with a legitimate health care facility.