10 Nutrition in Healthy Living

10.1 Overview

Evidence suggests that lifestyle is a significant determinant of our overall health and that our food choices play an important role in managing the risk of chronic disease. Chronic disease (a reoccurring condition that often requires medical intervention) is a leading cause of early death in the United States, and reducing risk is a national goal.

One way that health care professionals monitor the risk of chronic disease is a lipid panel, a blood test that measures cholesterol, triglyceride, and lipoprotein molecules circulating in the blood. Why? There is a relationship between elevated levels of LDL and chronic disease. This is one of the reasons why the US National Institute of Health (NIH) recommends that starting at twenty years old, you have a blood lipid panel evaluated and that you repeat it every five years. This creates a history that your health care professional can monitor for changes in disease risk.¹

Did you know that your body fat percentage impacts your ability to maintain good health and avoid chronic disease? The CDC reports that 40 percent of US adults are obese. One measure that health care professionals use to estimate the risk of obesity-related diseases, such as diabetes, high blood pressure, and gallstones, is the body mass index (BMI).^2,3 Calculate your BMI by dividing your weight in kilograms by your height in meters squared (BMI = kg / m2) and comparing the result to a set of categorized ranges from underweight to obese in the Body Mass Index Table provided by the NIH. Another quick estimate of body fat is waist circumference. A waist greater than forty inches for men and thirty-five inches for women indicates abdominal fat and an increased risk of chronic disease.⁴

The incidence of diabetes mellitus has grown worldwide in connection with unhealthy lifestyle choices, including eating habits and lack of exercise. There are four types of diabetes: gestational, prediabetes, type 1, and type 2, each of which has different characteristics and long-term consequences.

Gestational diabetes affects about 9 percent of all pregnant women and, left untreated, results in fat baby syndrome, or a baby that weighs greater than eight pounds at birth.⁵ Prediabetes precedes type 2 and is diagnosed when elevated blood glucose levels are found. Type 1 is acute and requires an external source of insulin. Untreated diabetes erodes health and damages tissue.

Objectives

• Recognize the impact of lifestyle on health and disease
• Relate lifestyle choices to heart disease risk
• Illustrate the link between body weight and chronic disease
• Recognize the different types of diabetes

10.2 Nutrition in Heart Disease

Overview

Chronic disease is a leading cause of early death in the United States. The US Center for Disease Control and Prevention reports that six out of ten people will have at least one chronic disease during their life, and chronic diseases account for a majority of all deaths. The nationwide prevalence of this type of illness reduces productivity and contributes to unprecedented medical costs. Chronic diseases include diabetes, chronic lung disease, heart disease, and cancer, among others.⁶

Widely available evidence points to lifestyle as a determining factor that influences the risk of developing a chronic disease. While some causative factors, such as genetic inheritance, are beyond your control, your lifestyle is not.

Lifestyle affects disease initiation, rate of progress, and consequences. Healthy habits that reduce risk include eating nutritious foods, engaging in physical activity, and avoiding tobacco. Chronic disease is not easily cured. Fortunately, wise lifestyle choices minimize progress and diminish impact.

Key Concepts

• Eating habits and how they influence the risk of heart disease
• Blood cholesterol and how it is used to assess cardiovascular health
• The importance of a regular check of blood lipoproteins

Heart Disease

Heart disease develops over time and is characterized by the deposition of fatty materials, or plaque, in arteries. Fatty deposits change blood flow. As blood diverts around plaque, a smooth flow grows turbid, leading to damaged arteries. Furthermore, when deposits block arteries, heart muscles receive less oxygen, and the risk of a heart attack increases.

How do eating habits influence your risk of heart disease? By allowing you to consume too many calories or too much fat, these habits can jeopardize your future. Diets high in saturated fat and/or trans fats increase the likelihood of fat deposition in arteries. Why? These substances increase the LDL content of your blood. LDL carries cholesterol and triglycerides from the liver to body tissues and, in the process, deposits fat in arteries. In addition, high quantities of saturated fat and trans fat traveling in the blood damage artery walls.

Fats in Foods

Animal-based foods are a source of saturated fat and the only source of cholesterol. While past health recommendations stressed minimizing or eliminating dietary cholesterol, recent research found a weak connection between dietary cholesterol and blood cholesterol levels, and recommendations are more moderate today^.7

Emphasis has shifted to the types of fat consumed and a recognition that saturated fats increase the risk of heart disease, while certain types of monounsaturated and polyunsaturated fats reduce risk. Once processed foods were a major source of trans fats, found in hydrogenated vegetable oils that were used to make spreadable plant-based fats such as margarine or shortening. Now these products are manufactured using a vegetable oil blend of saturated plant oils such as palm or coconut oil and a polyunsaturated fat like soybean oil; however, keep in mind that palm oil is high in saturated fat.

Overall, a diet that moderates consumption of high-fat foods reduces risk, as does one that increases consumption of fruits, vegetables, and whole grains. Don’t forget, the heart is a muscle, and physical activity strengthens muscles!

Understanding Blood Cholesterol

In 2013 the National Heart, Lung, and Blood Institute (NHLBI) released the third report of the expert panel on blood cholesterol in adults.⁸ The panel recommended that starting at age twenty, you should have your blood cholesterol measured once every five years. A lipoprotein profile provides information about your total cholesterol, LDLs, HDLs, and triglycerides and helps you assess your risk of heart disease and stroke. See Tables 10.1-10.4.

While LDL is the vehicle for unhealthy cholesterol buildup in arteries, HDL is a reverse transport from arteries back to the liver. Perhaps you have heard that LDL is “bad” cholesterol and HDL is “good.” This designation is based upon the relationship each has to the deposition or removal of harmful deposits in arteries.

Elevated LDL levels indicate an increased risk of heart disease, whereas higher levels of HDL are associated with a reduced risk. HDL levels of 60 mg/dL or greater are desirable, while those below 40 mg/dL are a cause for concern.

Blood levels of triglycerides, a third type of fat, are also measured to assess heart disease risk. Levels of 150-199 mg/dL are borderline high, while those of 200 mg/dL and above are high and should be addressed with your physician. A person with consistently high total cholesterol or triglycerides levels has a condition called dyslipidemia.

Summary

Chronic disease affects six out of ten people living in the US and is a major public health concern. Lifestyle changes offer opportunities to reduce personal risk by limiting consumption of saturated fat and replacing those food sources with one high in monounsaturated and polyunsaturated fats. A lipoprotein panel reports milligrams of cholesterol per deciliter of blood. It details the amount of healthy cholesterol, HDL, and unhealthy cholesterol, LDL, circulating in the blood. HDLs are considered beneficial, as they remove cholesterol deposits in arteries to the liver. LDLs are considered unhealthy because they deposit cholesterol in the arteries, causing damage and plaque formation.

10.3 Nutrition in Weight Management

Overview

In 2018 the US Centers for Disease Control and Prevention estimated that 72 percent of adults age twenty and older living in the US were overweight or obese.3 As a result, they were at increased risk of hypertension, dyslipidemia, type 2 diabetes, coronary heart disease, stroke, gall bladder disease, osteoarthritis, sleep apnea (interrupted breathing during sleep that results in low oxygen levels), and certain cancers.

Key Concepts

• Weight- and height-based formulas that estimate disease risk
• Body measurements that give a secondary estimate of disease risk
• Healthy eating habits and physical activity for a healthy lifestyle

How Weight Categories Are Calculated

BMI and waist circumference are two measures that are used to estimate your risk of obesity-related diseases. BMI estimates body fat by comparing weight to height. It is a more reliable measure of body fat than weight alone.

A word of caution—while BMI is accurate for most people, it underestimates the fat proportion of the very old who have replaced too much muscle, or lean body mass (LBM), with fat. It also overestimates muscular individuals who have an unusually high ratio of LBM to fat. For example, an elderly man might carry more fat than a BMI calculation indicates, while a young woman on a track team might have less. A BMI under 18.5 is underweight, and one from 18.5-24.9 is within a healthy range. Overweight is classified as 25.0-29.9, and obesity is 30 or greater.

A Second Measure—the Waist

A large waist circumference suggests an unhealthy blood cholesterol level. Why? Fat in the abdomen more readily influences the cholesterol and triglyceride content of the blood than fat stored in the hips and thighs. As your waist expands, your risk of obesity-related chronic disease does also. A waist circumference measurement can determine if an individual has increased risk despite a normal or overweight BMI.

Relating Waist Measurements to Chronic Disease

To measure your waist circumference, place a measuring tape snugly around your waist, the narrowest part of your body between your ribs and hips. Obesity-related health risks increase with a waist measurement of over 40 inches (102 centimeters) in men and over 35 inches (88 centimeters) in women. Risks include type 2 diabetes, hypertension, and cardiovascular disease.

A significant portion of the US adult population is overweight or obese. This happens when eating habits and consumption of energy nutrients (protein, carbohydrate, and fat) and alcohol exceed the amount of energy needed for body maintenance and physical activity.

Weight Management

Lifestyle choices concerning food selection result in obesity if too much food is consumed or if diets are not balanced. For those who are obese, a modest weight loss of just 10 percent lowers risk and marks a good beginning toward better health. Preventing further weight gain is recommended for someone who is in the normal or overweight range but who is without a high waist measurement.

Thinking about losing weight? The US Department of Agriculture has online resources that can help you plan a healthy weight loss program.⁹

Here are some pointers:

• Set a reasonable, realistic weight loss goal.
• When reducing calories, have a nutritionally balanced eating plan.
• Include regular physical activity.
• Write a behavior-change plan to help you stay on track.

What’s available to help you eat healthily? Shopping tips from the NHLBI recommend comparing nutrition facts labels on packaged foods and selecting the one with the lowest total calories per serving.¹⁰ If you are thinking about minimizing fat sources, remember that a calorie is a calorie, regardless of whether it is from carbohydrate or fat. Be careful not to restrict healthy fats by focusing on carbohydrate-rich foods simply because they are fat-free. These foods might be similar or higher in calories than the regular version. The NHLBI Aim for a Healthy Weight web page includes a listing of low-fat, low-calorie food alternatives from the dairy, grains, meats, snacks and sweets, fats and oils, and baked and miscellaneous groups.

Physical Activities

Did you know that there are four types of physical activity that you should include in your exercise routine?¹¹ Aerobic, muscle strengthening, bone strengthening, and stretching are activities that benefit the heart and lungs, improve strength and endurance, and keep bones strong.

Health benefits from physical activities increase with intensity. Daily routines such as driving a car or loading a dishwasher are light activities that don’t require much effort. Moderate-intense activities ask more of your heart and lungs and so return greater health benefits. How do you know when you’ve reached moderate intensity? You can talk but not sing.

What about vigorous-intensity activities? These activities make your heart, lungs, and muscles work and work hard! When you’re exercising vigorously, you can’t say more than a few words without getting out of breath.

Source: How Much Physical Activity Do Adults Need? US Centers for Disease Control and Prevention. https://www.cdc.gov/physicalactivity/basics/adults/index.htm. Reviewed May 14, 2020. Accessed January 16, 2021.

Summary

Managing a healthy weight and avoiding excess body fat is an important part of an overall healthy lifestyle. Excess body fat, particularly in the abdomen, is associated with an increased risk of chronic disease. Several tools are available for estimating body fat percentage. BMI uses height and weight to calculate a value that is categorized as underweight, healthy weight, overweight, and obese. Waist circumference is a second tool that provides an estimate of abdominal fat, which is used as an indicator of disease risk.

While making nutritious food choices that moderate total calories is an essential part of weight management, physical activity is needed too. The US Department of Agriculture; the Centers for Disease Prevention and Control; and the National Heart, Lung, and Blood Institute provide online tools for estimating calories in food and strategies for achieving physical activity goals.

10.4 Nutrition in Diabetes

Overview

In a 2015 study, the American Diabetes Association estimated that thirty million people in the US, or 9 percent of the population, had diabetes. While an estimated twenty-three million were diagnosed, an additional seven million were unaware that they even have the disease.¹² Current knowledge suggests that risks include advanced age, certain ethnicities, family history of diabetes, overweight or obese BMI accompanied by low physical activity, hypertension, and diabetes during pregnancy.

Symptoms of uncontrolled diabetes include frequent urination, excessive thirst, extreme hunger, unusual or rapid weight loss, fatigue, irritability, and blurry vision. Anyone who experiences these symptoms should seek medical advice. Adverse outcomes associated with uncontrolled diabetes include heart and kidney disease, dental disease, stroke, eye disorders and blindness, skin and foot infections, and nerve damages leading to loss of sensation in hands and feet.

Diabetes is characterized by the body’s inability to produce adequate amounts of insulin or to effectively use the insulin that it produces, resulting in excess amounts of glucose in the blood. Excess blood glucose, or hyperglycemia, impairs the immune system and damages the circulatory system. In addition, it glycates or modifies a variety of body proteins that are subsequently bound and no longer capable of function. Deposited in the eyes and kidneys, these irreversibly modified proteins damage membranes and cause kidney failure and blindness. Circulating in the blood, they damage the vascular system, resulting in heart disease and stroke.

Insulin is a hormone that body cells need to properly handle the energy nutrients—carbohydrate, protein, and lipid. When you eat food containing carbohydrates, blood glucose levels rise, and the beta cells of the pancreas respond by secreting increasing amounts of insulin. In fact, simply the sight, smell, and taste of food stimulate increase production. Insulin enables the movement of glucose across cell membranes, and when it is lacking, or when cells are insensitive to it, glucose remains in the bloodstream, and damage results.

There are four classifications of diabetes: type 1, type 2, gestational, and prediabetes. A definitive diagnosis results from the measurement of blood glucose levels after ingesting a specific amount of carbohydrates while fasting.

Key Concepts

• Insulin in glucose regulation
• Types of diabetes mellitus
• Testing blood glucose levels

The Role of Insulin

Insulin is a hormone produced by the beta cells in the islets of Langerhans in the pancreas. It is secreted into the bloodstream by the pancreas, where it helps body cells absorb glucose and synthesize proteins and lipids. Insulin is required for the transport of glucose across cell membranes and into the cell, where energy production takes place. In the absence of glucose, cells cannot absorb glucose and starve. In uncontrolled diabetes, glucose remains outside the cells and accumulates in the blood. Persistent high blood glucose levels damage the eyes, kidneys, nerves, and heart.

While diabetes occurs in people of all ages and races, some groups have a higher risk for developing type 2 than others. Type 2 is more common among African Americans, Latinos, Native Americans, and Asian Americans / Pacific Islanders than it is among Anglos. Obesity contributes to chronic disease risk for people of all ages. In addition, risk of diabetes increase with age, regardless of ethnic origin or race.

Type 1 Diabetes

Individuals with type 1 diabetes represent only about 5-10 percent of all people living in the US with diabetes. Type 1 is characterized by hyperglycemia (elevated blood glucose levels), polydipsia (excess thirst), polyuria (excess urination), glycosuria (glucose in the urine), dehydration, increased appetite, and weight loss.

Type 1 diabetes involves a genetic predisposition and a triggering event, such as a traumatic injury or illness. An autoimmune attack on the insulin-producing cells of the pancreas is triggered. Eventually, insulin-producing cells are destroyed and can no longer supply the body with insulin. The onset of symptoms is sudden, and an external source of insulin is required to correct blood glucose levels and prevent severe complications and possible death.

Typically diagnosed in children and young adults, the onset of type 1 diabetes usually occurs before forty and most commonly around fourteen years of age. Of the 23 million people diagnosed in 2015, only 1.25 million were classified as type 1 diabetes.¹³

Type 1 diabetes is characterized by an inability to make insulin. People with type 1 take daily shots of insulin and use insulin pens or other injection devices like an insulin pump. Other options include an implantable device and, for some types of insulin, an inhaler. Insulin is a protein-based hormone that cannot be consumed in tablet form. Why not? The digestive process renders it inactive. As a result, insulin must be delivered via a shot.

Type 2 Diabetes

Type 2 diabetes is more common than type 1 and is characterized by insufficient insulin production and body cells that resist or are insensitive to insulin. It typically involves a genetic tendency characterized by a resistance to the action of insulin by body cells. As body cells become more and more resistant, the pancreas adapts by producing ever-increasing amounts, until finally, insulin-producing cells are exhausted, and production falls.

Obesity is thought to cause insulin resistance; however, people of normal weight also can exhibit these symptoms. This condition may persist for some time before diagnosis.

Individuals with either type of diabetes are at increased risk of heart and vascular disease. Achieving a desirable body weight, getting exercise, maintaining blood glucose levels within the normal range, and eating low to moderate amounts of fats all contribute to lowering the risk.

Gestational Diabetes

Pregnant women without a prior history of diabetes but who develop high blood glucose levels during pregnancy experience gestational diabetes. The US Centers for Disease Control and Prevention estimates that 2-10 percent of pregnancies are affected by gestational diabetes.¹²

Pregnancy increases insulin needs by a factor of three. Hormones from the placenta that help the baby develop also block the action of the mother’s insulin in her body, making her cells resistant. If the mother fails to produce enough insulin to overcome this resistance, glucose remains in the blood, and levels grow too high.

Untreated gestational diabetes results in “fat baby” syndrome. Why? Elevated maternal blood glucose levels push excess glucose across the placenta and into the baby’s body. As a result, the baby receives more energy than is needed for growth. To compensate, the baby produces additional insulin that pulls excess glucose into cells, where it is stored as fat, resulting in a baby with a heavy birth weight.

Women who experience gestational diabetes have a two in three chance of recurrence during subsequent pregnancies. Additionally, many develop diabetes later in life.

Prediabetes

Prediabetes, or blood glucose levels that are higher than normal but not yet high enough to be diagnosed as diabetes, often precedes type 2. In 2015 the American Diabetes Association estimated that eighty-four million people in the US age eighteen and older had prediabetes.⁹ During prediabetes, long-term damage to the body, especially the heart and circulatory system, is silently taking place. Lifestyle changes can prevent or delay the onset of type 2 diabetes. Even those with a high risk for developing the disease benefit from lifestyle interventions that include a healthy diet and moderately intense physical activity.

Fasting Blood Glucose

The fasting blood glucose (FPG) is usually calculated in the morning when you have not eaten for a number of hours. In a healthy person without diabetes, a normal fasting blood glucose value is 72-99 mg/dL. A value of 100-125 mg/dL indicates prediabetes and is called impaired fasting glucose (IFG). At this stage, type 2 diabetes has not yet developed, although it may do so in the future. Diabetes is indicated when a value of 126 mg/dL or above is confirmed by a repeat test.

Oral Glucose Tolerance Test

The oral glucose tolerance test (OGTT) requires you to fast for at least eight hours. Your plasma glucose is measured immediately before and two hours after you drink a liquid containing seventy-five grams of glucose dissolved in water. If your blood glucose level is between 140 and 199 mg/dL two hours after drinking the liquid, you have prediabetes. When a two-hour glucose level of 200 mg/dL or above is confirmed by a repeated test, diabetes is indicated.

What is equivalent to seventy-five grams of carbohydrates? One piece of regular-sized white bread contains about fifteen grams. You’d need five slices to equal seventy-five grams.

OGTT for Gestational Diabetes

Gestational diabetes is diagnosed based on plasma glucose values measured during the OGTT. Blood glucose levels are checked four times on the test day, which is usually scheduled sometime between the twenty-fourth and twenty-eighth week of pregnancy. Gestational diabetes is present when blood glucose levels are above normal at least twice during the test.

Summary

Characterized by the body’s inability to produce adequate amounts of insulin or to use it effectively, diabetes is a chronic disease that affects millions of people living in the US. Type 1 diabetes is caused by an autoimmune response to an adverse health event that destroys the insulin-producing cells of the pancreas. A minority of people with diabetes have type 1. Most people with diabetes have type 2, in which body cells are insensitive to insulin, and as a result, blood glucose levels rise to unhealthy levels. Treatment of type 1 requires an external source of insulin, while type 2 is treated with both oral medications and insulin. Glucose levels are measured with a fasting blood glucose test and an oral blood glucose test.

References

This page lists the sources cited in this chapter. References connect to websites with keywords at the beginning of the citation. If you are using a screen reader, you should know that the full web address is listed after the meaningful word to provide for printing.

1. High Blood Cholesterol: What You Need to Know. US National Institute of Health, National Cholesterol Education Program. https://www.nhlbi.nih.gov/files/docs/public/heart/wyntk.pdf. Published June 2005. Accessed January 16, 2021.
2. Adult Obesity Facts. US Centers for Disease Control and Prevention. https://www.cdc.gov/obesity/data/adult.html. Updated August 2018. Accessed January 16, 2021.
3. Prevalence of Obesity among Adults and Youth: United States 2015-2016. National Center for Health Statistics, US Department of Health and Human Services. https://www.cdc.gov/nchs/data/databriefs/db288.pdf. Published October 2017. Accessed January 16, 2021.
4. Assessing Your Weight. US Centers for Disease Control and Prevention. https://www.cdc.gov/healthyweight/assessing/index.html. Updated January 2020. Accessed January 16, 2021.
5. Gao F, Luo H, Jones K, Nicholson W, Bell RA. Gestational diabetes and health behaviors among women: National Health and Nutrition Examination Survey, 2007-2014. Prev Chronn Dis 2018;15. doi:10.5888/pcd15.180094. Accessed February 3, 2020.
6. Soliman GA. Dietary cholesterol and lack of evidence in cardiovascular disease. Nutrients. 2018;10(6):780. doi:10.3390/nu10060780.
7. Management of Blood Cholesterol in Adults: Systematic Evidence Review from the Cholesterol Expert Panel. National Health, Lung, and Blood Institutes, US Department of Health and Human Services. https://www.nhlbi.nih.gov/health-topics/management-blood-cholesterol-in-adults. Published November 2013. Accessed January 16, 2021.
8. Interested in Losing Weight? US Department of Agriculture. https://www.nutrition.gov/topics/healthy-living-and-weight/strategies-success/interested-losing-weight. Accessed January 16, 2021.
9. Aim for a Healthy Weight. National Heart Lung and Blood Institute. https://www.nhlbi.nih.gov/health/educational/lose_wt/eat/shopping.htm. Accessed January 16, 2021.
10. Physical Activity and Your Heart. National Heart Lung and Blood Institute. https://www.nhlbi.nih.gov/health-topics/physical-activity-and-your-heart. Accessed January 16, 2021.
11. Statistics about Diabetes. American Diabetes Association. https://www.diabetes.org/resources/statistics/statistics-about-diabetes. Updated March 2018. Accessed January 16, 2021.
12. Gestational Diabetes. Centers for Disease Control and Prevention. https://www.cdc.gov/diabetes/basics/gestational.html. Reviewed May 2019. Accessed January 16, 2021.