You Do the Math
At the most basic level, weight comes down to a simple equation: If the calories you take in through foods and beverages equal the calories your body expends through its essential metabolic processes and the physical activity you do, your weight will remain stable. If the calories in are greater than the calories out, you'll gain weight. If they're less, you'll lose weight.
Calories In, Calories Out
A calorie is a measure of energy. Technically speaking, it's the amount of energy required to raise the temperature of one gram of water by one degree Centigrade. In terms of diet, the calorie is used to show how energy-dense a food is (how much potential energy it contains). The more calories a food contains, the more energy your body can get out of it. Your body breaks down food and gets its energy from it through the process of metabolism.
Your daily caloric needs are based on your gender, age, BMI, and activity levels. The average woman between thirty and fifty years old needs about 1,800 calories a day; a thirty-to-fifty-year-old man needs about 2,200. These are the recommendations for sedentary people — active people and athletes need more.
Scientists know that sweet tastes make us seek more of the same (which creates cravings and late-night ice cream binges). But sugar and other natural sweets (like fruit) can be less problematic than the fake stuff. Recent research shows that people who regularly consume artificially sweetened things like diet soda weigh significantly more than people who eat the real thing.
Unfortunately, most of us consume far more calories than we metabolize. All that extra energy is stored in the body as fat.
A pound of body weight represents 3,500 calories. It doesn't matter where they come from — salads and turkey burgers or French fries and mayonnaise — when you're talking about simple weight gain or loss.
By the same token, it doesn't matter, at least in the short term, if you create your calorie deficit by exercising three hours a day and eating sensibly or by starving yourself and popping diet pills. But in the long run, you'll be able to achieve and maintain a healthy weight only by combining nutritious and balanced meals with regular, vigorous exercise.
GI and TEF
Thanks to the popularity of the Atkins and South Beach Diets, most of us have heard of the glycemic index, or GI. This is a measure of your body's glucose (blood sugar) response to carbohydrate-heavy foods. High-GI carbs, such as sugars and highly processed grains, are digested quickly and create a rapid rise in glucose; low-GI carbs, such as whole grains and beans, are processed more slowly and produce a gradual blood-sugar increase. The more low-GI foods you eat, the lower the glycemic effect (GE) of your meal — and the more satisfied you'll feel.
The glycemic effect is determined by several factors, including the amount of fiber (higher fiber equals lower GE), fat, and protein on your plate. Generally speaking, a higher GE means a higher BMI.
Another consideration is the thermic effect of food, or TEF (thermogenesis is the process by which the body generates energy — or “burns off” the calories you consume). Scientists estimate that TEF — the energy it takes for your body to digest the food you eat — represents about 10 percent of your daily calorie expenditure.
Adding vinegar to your meal can reduce its glycemic effect — and its effects on your waistline — by as much as 55 percent. Vinegar contains acetic acid, which seems to inhibit your body's response to the carbohydrates you eat, leaving you feeling more satisfied and less likely to eat too much later.
Thus, eating foods with the highest possible TEF means burning more calories without expending any extra effort. Research shows that protein has a TEF that's as much as three times greater that carbohydrates or fat. Protein also produces greater satiety than other nutrients.
Of course, you can't eat all protein — experts recommend getting between 10 and 35 percent of the day's calories from protein. Thus, you've got to make your choices count.
