In This Chapter
Where did the calorie originate? The calorie, as we recognize it today, originates from the eighteenth century. Wilbur Atwater, a pioneer in the field of nutrition, is the scientist credited with developing the “Atwater system,” which was a means to measure the energy in food. His research was key in educating people about the importance of calories and their role in a healthy diet.
Everyone needs a certain amount of calories every day. Your body uses 60 percent of your total calories daily just to regulate itself while at rest. Another 10 percent are used in the digestion of food and absorption of nutrients. The remaining 30 percent are allotted for your activity needs. The U.S. Dietary Guidelines provide recommendations on how many calories you need each day based on your activity level, age, height, and gender. However, how your body metabolizes and burns those calories makes a huge impact on how easy or difficult it is to maintain your weight over your lifetime.
A calorie is a unit of measure. It is actually the amount of heat required to raise 1 kilogram of water 1° Celsius.
Let’s say you want to know how many calories are in an apple. A scientist would place the apple in a metal chamber, which is contained within another insulated metal chamber of water. This device, known as a bomb calorimeter, measures the amount of heat released from the apple when it’s cooked down to ashes. The measurements of the heat exchanged within the water are recorded and the data reveals that an apple provides about 93 calories.
Fortunately, the U.S. Department of Agriculture (USDA) maintains the food database that houses all the information about the nutrients specific foods contain, such as calories, vitamins, and minerals. The USDA has been collecting and analyzing data for more than 100 years, and with each new year more information is added.
What we have come to know as a “calorie” is technically a kilocalorie, which is equivalent to 1,000 calories. A kilocalorie contains enough energy to increase the temperature of 1 kilogram of water by 1° Celsius at sea level. A kilogram contains 1,000 grams and a kilocalorie contains 1,000 real calories. We simply refer to it as a calorie instead of the more accurate term kilocalorie or kcal.
Calories are found in carbohydrates, proteins, and fats. These are referred to as energy calories. Carbohydrates and proteins provide 4 calories per gram, fats provide 9 calories per gram, and alcohol provides 7 calories per gram.
Take a look at the calorie differences between the foods listed below. Fat and sugar provide the most calories in a small amount without any other nutrients besides energy calories. For example, a chicken breast and green beans provide much fewer calories by weight with an added bonus of valuable nutrients your body can use, such as proteins, vitamins, and minerals. It’s important to be aware where the majority of your calories come from.
Most foods contain a combination of carbohydrates, proteins, and fats, and it’s easy to calculate the total calories of a food item. If you know that a cup of dry cereal contains 15 grams of carbohydrate, 3 grams of protein, and 1 gram of fat, you would simply multiply it by the appropriate amount of calories per gram for each nutrient.
15 grams of carbohydrates × 4 calories per gram = 60 calories
3 grams of protein × 4 calories per gram = 12 calories
1 gram of fat × 9 calories per gram = 9 calories
60 + 12 + 9 = 81 total calories
The energy nutrients provide calories or fuel for your body to run on. However, in addition to energy, we use carbohydrates, protein, and fats as building blocks in the body, which we’ll discuss in greater detail in later chapters. If you consume more calories than your body needs each day, the extra calories are conveniently stored for later use. Unfortunately, over time these stored calories become unwanted pounds.
The U.S. government has established an estimated energy requirement (EER) to ensure we consume an adequate amount of energy each day to maintain health and ward off disease. Below is the table of estimated calorie requirements from the USDA Dietary Guidelines for Americans reported in 2010.
Estimated Calorie Needs per Day by Age, Gender, and Physical Activity Level
How to Calculate Your Calories
To calculate your basal metabolic rate (BMR), you need to know your current weight in pounds, height in inches, and age. Next take your numbers and plug them into the Harris Benedict equation, which will give you the total calories your body needs at rest.
How to Calculate Your Basal Metabolic Rate
Women: 655 + (4.35 × weight in pounds) + (4.7 × height in inches) – (4.7 × age in years)
Men: 665 + (6.23 × weight in pounds) + (12.7 × height in inches)- (6.8 × age in years)
Example: a 40-year-old woman, who is 5'6" tall and weighs 176 pounds
655 + (4.35 × 176) + (4.7 × 66) - (4.7 × 40)
655 + 756.5 + 310.2 – 188 = 1,533.7 calories
Now let’s calculate your activity factor by utilizing the following chart. Multiply your BMR by your activity factor to determine your total calorie needs for the day to maintain your current weight.
No exercise—mostly sitting
Light exercise (1-3 days per week)
Moderate exercise (3-5 days per week)
Heavy exercise (6-7 days per week)
Example: BMR 1,533.7 × 1.2 (no exercise) = 1,840.44 calories
Knowing your body’s total calorie needs will help you achieve your weight goals.
Basal Metabolism Rate (BMR)
Your basal metabolism rate accounts for about 60 percent of your daily energy needs. The body uses these calories while it’s at rest to carry out all types of key functions you don’t have to think about, such as breathing, pumping blood, and making new cells. BMRs vary between men and women because men have more lean muscle mass and muscle is metabolically active (burns more energy).
As you age, your BMR will decrease by about 2 percent per decade. This is due to a change in hormone levels, body composition changes such as a decrease in lean muscle mass, and decreased activity level.
Your BMR can also be negatively affected if you’ve followed very low-calorie diets and skipped meals for many years, which causes your body to hold tightly to its calorie stores by utilizing calories more efficiently. We’ll discuss this in more detail shortly.
Cutting Calories for Weight Loss
One pound of body fat is equivalent to 3,500 calories. According to a review of research published in Strategies to Prevent Weight Gain Among Adults, most people will gain 1 to 2 pounds each year in middle age. This is a slow and gradual increase over a long period of time, which can lead to obesity along with an increased risk of heart disease, hypertension, and diabetes.
An awareness of what your daily calorie needs are and a sensible approach to reducing calories for weight loss is the key to good health. The first step in cutting calories for weight loss is to create a calorie deficit each week through diet and exercise. First, determine whether you want to promote a half-pound or a whole pound of weight loss each week. A half-pound calorie deficit would equal 250 calories per day. A one-pound loss would require a 500 calorie deficit. Next, you would deduct 250 to 500 calories from your total daily calories to determine your calorie budget for the day to promote weight loss.
For example, if your total daily calories were 1,840, to maintain your weight you would subtract 500 calories from your total: 1,840 - 500 = 1,340 calories. Next, you want to distribute those 1,500 calories throughout the day into three meals: breakfast, lunch, and dinner, and two snacks. A good plan would be to have 350 calories at breakfast, 350 calories at lunch, and 350 calories at dinner, with two snacks of 145 calories each in between meals.
You may realize that by implementing this regimen with more frequent meals, it seems to be much more food than you typically have been eating—and it may very well be. By eating frequent meals, you’ll help stave off hunger and regularly fuel your body. Keep in mind that your body uses about 10 percent of its total calories to digest and assimilate food, so you might just be getting a slight metabolic increase from what you were previously.
Earlier we stated that muscle is metabolically active, meaning it burns more calories at rest. If you exercise and build more lean muscle mass in your body, you’re going to increase the total amount of weight lost each week. By pairing eating fewer calories along with increased calorie burn from activity, you have a winning combination. There are no tools or exercise equipment required to be more active. All you need is a good pair of comfortable walking shoes—in a brisk 30-minute walk, you can burn off about 100 additional calories.
What Is an Empty Calorie?
Some calories are referred to as “empty” calories. This is a misnomer because there aren’t really any calorie-free whole foods. An empty calorie is one in which the majority of calories are from sugary or fatty foods that don’t provide any additional vitamins or minerals. This includes alcoholic beverages, too. Examples of empty-calorie foods include ice cream, candies, cookies, sodas and energy drinks, alcohol, and hot dogs.
Many people fill up on these types of foods and have no room left to eat more nutritious ones. The good news is when you eliminate these empty-calorie food sources from your diet you have more calories to use on healthier food options. Having some empty calories in your diet is allowable, but it should fit within your calorie budget.
One area where calories can add up quickly is with alcoholic beverages. Over the course of an evening, you could easily rack up an extra 300 calories with just a couple of drinks.
Your best low-calorie choices are light beer at 95 calories, 1½ ounces of hard liquor with a zero-calorie mixer, or a glass of wine. Be wary of mixed drinks and know your calorie budget when including cocktails.
Determining whether you’re at a healthy weight is important for good health. However, keep in mind that numbers are just that, and they don’t show the whole health picture. It’s important to take everything into consideration when assessing your health status: genetics, BMI, frame size, muscle and fat percentages, and location of your body fat, along with an evaluation of your blood lipid levels.
Research from the Centers for Disease Control and Prevention (CDC) shows that those who live the longest are actually considered to be in the “overweight” and “mildly obese” categories. The studies suggest that people with a BMI of 25 to 29.9 may outlive those with higher and lower BMIs.
Body Mass Index (BMI)
Body mass index (BMI) is a calculation used by many health practitioners to determine if a person is at a healthy weight based on their weight-to-height ratio. It helps them gauge the risk of disease as related to weight status. Some of the criticism over the use of this measure is that it was based on healthy population studies and doesn’t take into consideration that women have more body fat than men, older people have more body fat than younger adults, and athletes have a higher muscle mass.
To calculate your BMI, you take your weight in pounds divided by height in inches squared × 703. For example, let’s say you are 150 pounds and 5'7":
150 pounds ÷ 67 × 67 inches × 703 = 23.49
BMI = 23
You can determine your risk of heart attack if you’re over 20 years old and don’t have heart disease or diabetes by using the heart attack risk assessment and BMI calculator provided at the following websites:
Heart Attack Risk Calculator:
30.0 and above
BMI is an inexpensive and quick gauge of health as opposed to other more complicated methods to evaluate the fat level. Additional methods to determine levels of body fat are more expensive, require trained staff, and are not all portable. These include skin-fold measures taken with calipers, underwater weighing, bioelectrical impedance, and dual-energy x-ray absorptiometry (DXA).
BMIs can be higher than 35. A BMI of 40 or more is considered severe obesity or morbidly obese, which equates to about 100 pounds over your ideal body weight. However, you can be classified as morbidly obese if you have a BMI of 35 and the presence of obesity-related health issues such as diabetes or high blood pressure.
Long-Term Weight Management
According to a report by the National Health and Nutrition Examination Survey (NHANES), over 70 percent of Americans have a BMI greater than 25, which classifies them as overweight or obese. Individuals categorized as overweight or obese have an increased risk of developing conditions and diseases such as high cholesterol, diabetes, hypertension, metabolic disorders, and heart disease.
Distribution of fat is a critical component in assessing the risk factor for developing certain metabolic disorders. Carrying weight in the lower portion of the body, primarily the hip and buttocks region, is called gynoid or “pear” shape. If an individual carries their body weight around their middle or abdominal area, they have an android or “apple” shape. The apple style of weight distribution generally denotes an increased amount of internal fat, known as visceral fat, around the organs. Visceral fat increases the risk for hypertension, heart disease, and type 2 diabetes.
Treating weight gain involves a combination of exercise, diet, and behavior modification. Environment is an important component of behavior modification. Factors in the environment can trigger the desire to eat, such as the smell and sight of food. These factors can also trigger the selection of types and quantities of food. Social cues such as food selection of dining partners and cognitive cues like how you feel about food can also affect your behavior.
Setting a realistic weight-loss goal is crucial. Endotext, a nonprofit web-based source of information on endocrine disease, recommends a 10 percent weight-loss goal over 6 months as a realistic reduction. By focusing on a weekly goal of losing 1 to 2 pounds, you should achieve your 10 percent goal within a 6-month period. The National Weight Control Registry reports individuals who monitor their weight closely with frequent weigh-ins (daily to weekly) are able to modify their behavior instantly and achieve better results than those who did not weigh in on a frequent basis.
Reducing daily calorie intake by 250 to 500 calories and making small changes is key to changing your behavior. Endotext reports individuals who reduce their calorie intake and limit their fat intake to 20 to 30 percent of their ingested calories had greater success in weight reduction than calorie or fat reduction alone.
When you decrease your calorie intake, you will likely lose weight. Losing weight is followed by adaptive thermogenesis. Your body has less of you to move and therefore requires fewer calories. This is why increasing activity levels is important for ongoing weight loss and management.
Thermogenesis is energy produced from the breakdown and processing of the food you eat. Adaptive thermogenesis is when your body regulates the production of heat (burning of calories) in response to environmental changes in temperature and diet, which causes metabolic inefficiency.
Eating More for Weight Gain
Trying to gain weight can be just as big of a hurdle as losing weight. It requires the same amount of dedication to achieve your weight goals. In order to gain 1 to 2 pounds per week, take your total calorie needs for the day and increase them by 500 to 1,000 calories. Distribute the 500 to 1,000 calories over each meal and snack times. For example, if your calorie requirements are 2,000 per day, add 100 to 200 calories at each mealtime. You can easily add an extra 100 calories to your diet by eating ¼ cup of granola, 1 cup of air-popped popcorn, 1 ounce of cheddar cheese, or 15 almonds.
When eating (or the lack of eating) becomes such a personal obsession that it disrupts normal daily living, an eating disorder is most likely the cause. According to the National Association of Anorexia Nervosa and Associated Disorders, about 24 million people suffer from an eating disorder. The primary types of eating disorders are anorexia nervosa, bulimia, and binge eating. Each disorder revolves around extreme emotions, behaviors, and attitudes toward food. Becoming preoccupied with food and weight is a sign that an eating disorder may be present.
Multiple psychological and neurochemical factors lead to eating disorders. Disordered eating is prevalent among athletes due to weight requirements for certain sports like gymnastics and wrestling. These disorders can lead to serious life-threatening health issues, and more people die from eating disorders when compared to other forms of mental illness.
Anorexia, as it is commonly referred to, is when a person eats too little food to maintain a healthy weight. A person with anorexia has an intense fear of weight gain and a distorted body image, which is linked to self-esteem. Anorexia affects about ½ to 1 percent of girls or women, according to the National Eating Disorders Organization.
Some of the key warning signs of anorexia nervosa are extreme weight loss, preoccupation with weight and dieting practices, avoidance of certain foods, constant references to being overweight, excessive exercising, and withdrawal from social situations. Those who suffer from anorexia not only restrict food, but they can also binge and purge on foods to control body weight. Severe food restriction can cause muscle wasting, hair loss, and overall malnutrition.
Treatment for anorexia involves psychological and nutritional counseling. In extreme cases, an in-patient approach is necessary with 24-hour supervision in a specialized treatment facility. Of those who are diagnosed, between 5 and 20 percent die from the disorder.
Bulimia is an eating disorder characterized by repeatedly eating large amounts of food and then purging the food with self-induced vomiting or use of laxatives, along with excessive exercise to prevent weight gain. It affects 1 to 2 percent of adolescent and young adult women. A person with this type of eating disorder feels out of control and has self-esteem issues related to body image.
Some of the warning signs of bulimia are swelling of the cheeks or jaws, discoloration of teeth, rigid exercise routines, and frequent trips to the bathroom after meals. This disease adversely impacts the body by the repeated use of vomiting, which damages the gastrointestinal tract and disrupts the body’s natural fluid balance. Treatment involves psychological and nutritional counseling along with antidepressants.
Binge-Eating Disorder (BED)
Binge-eating disorder (BED) is characterized by consuming large amounts of food in a very short period of time. A person with this type of eating disorder will typically binge in private and experience extreme feelings of guilt, shame, and being out of control during the episode. According to the National Eating Disorder Organization, it affects 1 to 5 percent of people in the United States, with about 60 percent being female and only 40 percent male. Those with BED can be of average weight or classified as overweight.
Symptoms include frequent consumption of large amounts of foods in private, depression, eating until it hurts, and managing weight gain through self-induced vomiting. Repeated binge-eating episodes can lead to obesity along with obesity-related diseases, such as heart disease, diabetes, gallbladder disease, and high blood pressure. Treatment typically involves psychotherapy, nutritional counseling, and antidepressants.
A relatively new eating disorder, orthorexia is not classified in the Diagnostic and Statistical Manual of Mental Disorders (DSM). Introduced by Dr. Steven Bratman in 1997, orthorexia is closely related to anorexia nervosa. However, anorexics want to control weight, whereas in people with orthorexia, weight is not the focus. In orthorexia, a person has an obsession with eating “healthy” foods. The focus is on food quality, purity, and wholesomeness, along with avoidance of chemicals like preservatives or animal products. The consequences of this can lead to malnutrition and being underweight.
People affected by orthorexia may have started out by changing their eating habits to become healthier. However, the diet spirals out of control and turns into an obsession. These people may spend hours reading food labels, are preoccupied with how eating an “impure” food will impact their health, and also may believe they’re better than other people for following such a “perfect” diet. Recovery is possible for those suffering from orthorexia. Treatment is similar to anorexia and involves psychological and nutritional counseling.
Tracking Your Calories
There are many ways to track your calories and monitor your progress when it comes to losing or gaining weight. Many people use the pen and paper method of a food log in which they write down what they ate, when they ate, and the estimated calories of each meal. Others may prefer to use a digital version. In today’s electronic realm, there are even apps to help you keep track of your calories. Some apps even let you take photos of what you eat with your phone or tablet and the software calculates, tracks, and graphs your progress in full color.
It’s important to know where the majority of your calories are coming from because it makes you aware of areas for improvement. You may learn that your meals are out of balance and don’t have a healthy ratio of carbohydrates, proteins, and fats. It also helps identify if you are eating too much or too little which can cause unwanted weight gain or weight loss. It’s hard to make changes in your diet if you don’t know what you’ve been doing. And with today’s technology at your fingertips it makes calculating calories easy. Knowing your total calorie needs for the day, how many calories you need to maintain your weight, and your BMI can help define your health goals and lead to better health.
You also need to be mindful and realize that counting calories should be used as a tool to help guide your towards making healthier, well-balanced food choices. When the numbers get in the way of the joy of eating there may be an underlying disordered way of eating present that needs to be addressed.
The Least You Need to Know