Calories

Technically, these are "kilcalories," not calories. A calorie is the amount of energy required to raise the temperature of one gram of water by one degree Celsius (or 1.8 degrees Fahrenheit). Nutritionists measure food energy in units 1000 times larger¾hence the prefix kilo. But since most people and all food labels call this a "calorie," Diet Power does, too.

Your Daily Allowance

Diet Power defines your Personal Daily Allowance (PDA) of calories as your current calorie budget plus the daily average you earned through exercise over the past 30 days. (If you haven't been using the program that long, the program assumes "phantom exercise" for the period before you enrolled: 250 calories a day if you're a man, 150 a day if you're a woman.)

For most people, the PDA will fall within the Acceptable Macronutrient Distribution Range (AMDR) introduced by the Food and Nutrition Board in September 2002. Your PDA may fall outside the range if your metabolic rate is unusually high or low¾but this happens only rarely.

Don't Confuse Your PDA with Your Budget

Your budget is the number of calories you should net today after subtracting the exercise you actually got¾and the number you should heed if you want to reach your goal weight on schedule. The place to find your budget is not in your Nutrient History, but in your Calorie Tally.

On a weight-loss diet, your budget will usually be lower than your PDA; on a weight-gain regimen, it will usually be higher than the PDA¾depending on the amount of exercise you're getting. This means that during a weight-loss or maintenance diet, your Nutrient History may occasionally color your Calories bar blue for "good" when you've actually overeaten a bit.

(You may wonder, "If the calorie budget is the number I should monitor for weight control, why does Diet Power bother assigning me a PDA?" Answer: because Diet Power is also designed for watching your nutrient balance¾and some of your nutrient requirements depend on your PDA of calories, which defines how many you should eat, not how many you should net after exercise.)

To view your Personal Daily Allowance (PDA) of calories:

Look at the top line on the Energy Nutrients page in the Personal Daily Allowance Editor.

Upper Limit

The Food and Nutrition Board has not established a Tolerable Upper Intake Level (UL) for calories, but obviously any amount leading to overweight or obesity is too many.

To revise your PDA:

You can't¾at least not directly. Your PDA of calories is automatically determined by your metabolic rate, goal weight, and target date. The only way to change it is by starting a new diet, using the Goal Setter.

Color Coding of This Nutrient

(Note: The following definitions assume that you are on a weight-loss diet. If you're on a weight-maintenance or weight-gain diet, the colors may not apply to you. Always trust the length of the bars more than their colors.)

The calorie bar in your personal Nutrient History is:

·    blue for "good" if you've logged 50 to 100 percent of your PDA

·    red for "bad" if you've logged more than 100 percent of your PDA

·    yellow for "caution" if you've logged less than 50 percent of your PDA

·    missing if you've logged no calories.

In a food or recipe's nutrient profile, the calorie bar is nearly always blue for "neutral," because getting your entire PDA of calories from this item would, by definition, give you exactly 100 percent of your PDA of calories. The only exception is when the calorie bar is missing because the item has no calories.

How Complete Are Diet Power's Calorie Readings?

Absolutely complete. Of the 11,000 foods in Diet Power's dictionary, none list their calorie content as "unknown." And since you must fill in the "Calories" block when you add a food to the dictionary yourself, all of the user-added foods have calorie readings, too.

Calories on Food Labels

Virtually all foods are required to reveal the calorie content of a typical serving (defined as "the amount customarily eaten at one time"). They must also report how many of these calories come from fat.

The Daily Value for calories is, by definition, 2000, since that's the daily intake assumed for calculating all other nutrients' Daily Values. Two thousand calories is not necessarily right for you, however¾it's a rough estimate meant to cover most of the U.S. population.

For more information on label regulations, see Labels, Food.