the same number of calories per ounce. But if you serve the chicken without its skin, it contains very little fat, while the hamburger has a lot. So a 3-ounce serving of skinless chicken gives you 140 calories, while a 3-ounce burger yields 230 to 245 calories, depending on the cut of the meat and its fat content.
Empty calories
All food provides calories. All calories provide energy. But some foods are said to give you empty calories. This term has nothing to do with the energy the calorie provides. It simply describes a food whose protein, fat, and carb calories come “naked” without the additional nutrients such, as dietary fiber, vitamins, and minerals, that improve the nutrition value of the foods on your plate.
The best-known empty-calorie foods are table sugar and ethanol (the kind of alcohol found in beer, wine, and spirits). On their own, sugar and ethanol give you energy — but no nutrients. (See Chapter 8 for more about sugar and Chapter 9 for more about alcohol.)
Of course, sugar and alcohol are often found in foods that do provide other nutrients. For example, sugar is found in bread, and alcohol is found in beer — two very different foods that both provide calcium, phosphorus, iron, potassium, sodium, and B vitamins.
In the United States, some people are malnourished because they can’t afford enough food to get the nutrients they need. The school lunch program started by President Franklin Delano Roosevelt in 1935 and expanded by almost every president, Republican and Democrat, since then has been a largely successful attempt to prevent malnutrition among poor schoolchildren.
Some Americans live in “food deserts,” places where fresh produce and healthier options are just not available — or available but at really high prices.
Many other Americans who can afford enough food are malnourished because they simply don’t know how to choose a diet that gives them nutrients as well as calories. For these people, eating too many foods with empty calories may cause significant health problems, such as weak bones, bleeding gums, skin rashes, mental depression, and preventable birth defects. Too many empty calories may also lead to obesity, an epidemic in current American society and, increasingly, around the world, which I outline in Chapter 4.
KEEPING UP WITH KETO
Choose a basic balanced healthy diet, and your body runs on glycogen, the sugar produced when you digest carbohydrates. A ketogenic diet changes that by restricting carbs so that you burn fats instead. That leads to your liver’s creating ketones, alternate chemicals your cells can use for fuel, a situation called ketosis.
The original ketogenic (”ketone-making”) diet, created in the 1920s as a treatment for epileptic children who did not respond to anti-seizure meds, drew 90 percent of daily calories from fat, 6 percent from protein, and just 4 percent form carbs. After a year on this regimen, nearly half the children experienced fewer seizures, and 12 percent were actually seizure free, a result confirmed today by the Epilepsy Foundation.
The strictest modern medical keto diet is more flexible, reducing calories from fat to 75 percent of the daily total, raising calories from protein to 20 percent, and adding one percent point to carbs. Non-medical versions such as the multiple varieties of the Atkins diet promoted as a fast way to peel off the pounds, are even more relaxed. Caution: To date, there are no serious long-term studies that show that keto diets produce anything more than a temporary weight loss.
None of the keto diets are risk free. The most common side effects among children who followed the original ketogenic plan were constipation, weight loss, and growth problems thought to be due to limiting proteins. Today, obesity experts know that the keto diet may trigger high calcium levels in urine (hypercalciuria), kidney stones, temporarily high cholesterol, bad breath, dizziness, and, in the first few weeks, low energy levels commonly called the keto flu. This list of potential problems suggests that pregnant women, diabetics, and those with a history of kidney stones should not try keto without a doctor’s approval.
Every calorie counts
Although your body burns some calories faster than others — your first source of energy is carbohydrates, which you metabolize before fats — people who say that “calories don’t count” or that “some calories count less than others” are usually trying to convince you to follow a diet that concentrates on one kind of food to the exclusion of most others. One common example that arises like a phoenix in every generation of dieters is the high-protein diet.
Determining How Many Calories You Need
Think of your energy requirements as a bank account. You make deposits when you consume calories. You make withdrawals when your body spends energy on work. Nutritionists divide the amount of energy you withdraw each day into two parts:
The energy you need when your body is at rest
The energy you need to do your daily “work”
To keep your energy account in balance, you need to take in enough each day to cover your withdrawals. As a general rule, infants and adolescents burn more energy per pound than adults do, because they’re continually making large amounts of new tissue. Similarly, an average man burns more energy than an average woman because his body is larger and has more muscle (see the upcoming section “Sex, glands, and chocolate cake”), thus leading to the totally unfair but totally true proposition that a man who weighs, say, 150 pounds can consume about 10 percent more calories than a woman who weighs 150 pounds and still not gain weight. For the numbers, check out the next section and Table 5-1.
Resting energy expenditure (REE)
Even when you’re at rest, your body is busy. Your heart beats. Your lungs expand and contract. Your intestines digest food. Your liver processes nutrients. Your glands secrete hormones. Your muscles flex, usually gently. Cells send electrical impulses back and forth among themselves, and your brain continually sends messages to every tissue and organ.
TABLE 5-1 How Many Calories Do You Need When You’re Resting?
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