The number you really need to remember is 3,500, the number of calories it takes to gain or lose one pound of body fat. In other words, 3,500 food calories equal one pound of body weight. So if you simplyCut your calorie consumption from 2,000 calories a day to 1,700 and continue to do the same amount of physical work, you’ll lose one pound of fat in approximately just 12 days (approximately because different bodies burn calories/energy at different rates).Go the other way and increase calories from 1,700 to 2,000 a day without increasing the amount of work you do, approximately 12 days later, you’ll be one pound heavier.
Moderation is the best path to weight control. Moderate calorie deprivation on a sensible diet produces healthful, moderate weight loss; this diet includes a wide variety of different foods containing sufficient amounts of essential nutrients. Abusing this rule and cutting calories to the bone can turn you literally into skin and bones, depriving you of the nutrients you need to live a normal healthy life. For more on the potentially devastating effects of starvation, voluntary and otherwise, check out Chapter 14.
Be more active. Exercise allows you to take in more calories and still lose weight. In addition, exercise reduces the risk of many health problems, such as heart disease. Sounds like a recipe for success.
Although many Americans should work at losing weight, the fact is that many larger people, even people who are clearly obese, do live long, happy, and healthy lives.
To figure out why some overweight people’s health status doesn’t follow the “rules,” many nutrition scientists now focus on the importance of confounding variables — science speak for “something else is going on here.”
Here are three potential confounding variables in the obesity/health equation:
Maybe people who are overweight are more prone to illness because they exercise less, in which case stepping up the workouts may reduce the perceived risk of being overweight.SNOOZE TO LOSEIn 2010, two separate studies, one at the University of Chicago Medical Center and the other at the Division of Sleep Medicine at Brigham and Women's Hospital and Beth Israel Deaconess Medical Center in Boston, linked lack of several good nights’ sleep to weight gain. Naturally, that called for follow-up studies, and sure enough, in 2012, researchers at Columbia University College of Physicians and Surgeons discovered that sleep deprivation appears to impact the “fullness” hormones ghrelin (which says, “I need food”) and leptin (which says “Enough!”), producing more ghrelin, less leptin, and thus eventually more pounds on your body. In plain speak, a sleepy brain makes bad decisions whether for late-night snacking or reaching for a candy bar rather than an apple the following day.
People who are overweight may be more likely to be sick because they eat lots of foods containing high-calorie ingredients, such as saturated fat, that can trigger adverse health effects; in this case, the remedy may simply be a change in diet and a healthier lifestyle including, yes, exercise.
Chapter 5
Calories: Powering Up the Body
IN THIS CHAPTER
Automobiles burn gasoline to get the energy they need to move. Your body burns (metabolizes) food to produce energy in the form of heat that keeps you warm and (as energy) powers your every move and thought.
The amount of heat produced by metabolizing food is measured in a unit called the kilocalorie — the amount of energy it takes to raise the temperature of 1 kilogram of water 1 degree on a Centigrade (Celsius) thermometer at sea level.
°F = °C × 9/5 + 32
32°F = 0°C × 9/5 = 0 + 32 = 32°F°C = (°F – 32) × 5/9
0°C = (32°F – 32) = 0 × 5/9 = 0°C
Nutritionists commonly substitute the word calorie for kilocalorie. Strictly speaking, a true calorie is just 1/1,000 of a kilocalorie, but the word calorie is easier to say and easier to remember, so that’s what you see when you read about the energy in food.
Counting the Calories in Food
When someone says that a serving of food — say, one banana — has 105 calories, that means your metabolizing the banana produces 105 calories of energy your body can use for work.
Different foods have different amounts of calories depending on their nutritional components. For example, high-fat foods have more calories than low-fat foods because a gram of fat has more calories than a gram of carbs or protein or alcohol:
Protein has 4 calories per gram.
Carbohydrates have 4 calories per gram.
Fat has 9 calories per gram.
Alcohol has 7 calories per gram.
In other words, ounce for ounce, proteins and carbohydrates give you fewer than half as many calories as fat. That’s why — again, ounce for ounce — high-fat foods, such as cream cheese, are calorie-rich, while low-fat foods, such as fruits and vegetables, are not.
MEASURING THE NUMBER OF CALORIES
Nutrition scientists measure the number of calories in food by actually burning the food in a bomb calorimeter, which is a box with two chambers, one inside the other. The researchers weigh a sample of the food, put the sample in a dish, and put the dish into the inner chamber of the calorimeter. They fill the inner chamber with oxygen and then seal it so the oxygen can’t escape. The outer chamber is filled with a measured amount of cold water, and the oxygen in the first chamber (inside the chamber with the water) is ignited with an electric spark. When the food burns, an observer records the rise in the temperature of the water in the outer chamber. If the temperature of the water goes up 1 degree per kilogram, the food has 1 calorie; if it goes up 2 degrees, it has 2 calories; 235 degrees, 235 calories — or one 8-ounce chocolate malt made with powder mix and whole milk.
