What You Need
How much energy our bodies use daily depends upon three major factors:

1. How Much Muscle We Have
   This has the greatest influence on calorie needs because our muscles use energy 24 hours a day. This on-going energy (also known as your metabolism) accounts for the majority of our energy needs.



2. How Much Total Weight We Carry Around
   The heavier we are, even if the weight is extra body fat, the more energy our bodies need to move from point A to point B.



3. How Far We Move Our Weight in a Day
   People who are on their feet all day require more energy than people who spend most of their time sitting. Likewise, running burns more energy than walking for the same amount of time because running carries us farther. You might be surprised to learn that running two miles burns only slightly more calories than walking two miles because you cover the same distance.

Calorie Sources
Our bodies extract energy from four sources in foods:

• Fat
• Carbohydrates
• Protein
• Alcohol

Fat receives so much attention because it is the quickest way to rack up the calories in your daily caloric intake. Compare the calorie values of these basic foods:

• 1 tablespoon vegetable oil (pure fat) --120 calories
• 1 tablespoon sugar (pure carbohydrate) -- 45 calories
• 1 ounce very lean meat (protein and water) -- 35 calories
• 1 ounce (2 tablespoons) 90 proof liquor (alcohol and water) -- 75 calories

Many foods are combinations of fat, carbohydrates, protein and water. Being aware of these caloric breakdowns helps us understand why some foods are low in calories while others are high. For example, a food like cabbage, which is mostly water and a little carbohydrate, contributes only 20 calories per cup. On the other hand, a piece of apple pie that contains large amounts of fat and sugar, contributes about 400 calories.

Losing Weight
Every pound of stored body fat represents about 3,500 calories. If everyday for a week you use 500 calories more than you take in, you'll use up one pound of fat (500 calories x 7 days = 3,500 calories = 1 pound body fat). Doubling your efforts to eat less and exercise more would create a 1,000 calorie deficit per day. That leads to two pounds of fat lost in a week. This may not sound like much, but if you think of it over the long haul, instead of next month's class reunion, one to two pounds a week could add up to 50 to 100 pounds less a year from now.

Eating less fat is an effective way to shift your energy balance to your benefit, but beware! Not long ago, eating less fat meant avoiding potato chips, premium ice cream and greasy snack crackers. Today we can buy fat-free and reduced-fat versions of all of these. Watch out for the trap of eating more because you think a food has less fat. A handful of regular potato chips provides 120 calories. A handful and a half of fat-free potato chips also provides 120 calories.

The bottom line is energy balance.
If you consume more calories on average than your body uses, the extra energy (no matter what the source) becomes body fat. An extra 100 calories a day over a year becomes 10 pounds of fat!