Obesity is a major risk factor for poor health in women. In order to avoid overeating, it's important to understand how the body maintains energy balance: regulating energy intake so that it equals energy output.

Consider the following equation:

Energy In (food intake) = Energy Out

When energy intake exceeds energy output, weight gain occurs. When energy output exceeds energy intake, weight loss occurs. Any imbalance in this equation will have direct results on body weight. For instance, the individual who eats regularly, but receives little or no exercise will usually gain weight. The cancer patient with a decreased appetite and a rapidly growing cancer tends to lose weight. This individual is simply unable to keep up with the energy demands the cancer is placing on the body.

Food is essential because the body needs it to function properly. However, eating more food than the body needs leads to the storage of excess body fat. Exercise requires calories and helps consume body fat. These components must be balanced to achieve body weight goals.

The number of calories people need depends on their weight, age, and level of activity. The calculation of total caloric intake necessary to simply maintain a certain body weight is as follows:

Desired Weight (in pounds) multiplied by a level of activity value will equal the number of calories you need each day to maintain your weight.

Desired Weight x (level of activity value) = total calories needed per day

The level of activity value is determined as follows:

10	Light physical activity
15	Medium physical activity
20	Heavy level of physical activity

The total calories needed per day should be adjusted based on your age group. Use the chart provided below:

Age	Action
25-34	subtracts 0 from your total calories
35-44	subtracts 100 from your total calories
45-54	subtracts 200 from your total calories
55-64	subtracts 300 from your total calories
65 +	subtracts 400 from your total calories

The result obtained after this step should be a closer estimate of the total calories needed per day to maintain a desired weight, based on a commitment to a particular level of activity.

Once total calories are known, it is important to calculate the calories from each food group. Using the example above for a person who is going to consume 1,500 total calories per day:

1,500 total calories per day x 0.30 (30%) fat calories = 450 calories

This shows that 450 calories of the total 1,500 daily calories may be from fat sources. We also know that each gram of fat provides 9 calories, so that the person in our example can eat about 50 grams of fat per day (450 calories divided by 9 calories/gram of fat) and still be following these guidelines.

The same calculations can be performed for protein and carbohydrates. There are also many tables and simple computer calculators that will perform these tasks quickly and accurately.