Your caloric intake need is based on your estimated energy expenditure, which varies based on your ideal body weight, activity level, age, height and gender. To calculate your ideal caloric need post-amputation, you will need to determine your ideal body weight post-amputation and use an equation to find your estimated energy expenditure. This information will tell you what your calorie needs will be.
Calculate your ideal body weight pre-amputation. For men, the equation uses 106 pounds for your first 5 feet of height and adds 6 pounds for every inch above 5 feet. For women, the equation uses 100 pounds for the first 5 feet and adds 5 pounds for every inch above 5 feet. For example, consider a man who is 6 feet, 3 inches tall, which is 15 inches taller than 5 feet. Multiply 6 by 15 to get 90 pounds, and then add 90 to the original 106 pounds for his first 5 feet of height. This man's ideal body weight is 196 pounds.
Find the percentage of body weight you lost during the amputation. These percentages are standardized and a complete table of them can be found in the "ADA Pocket Guide to Nutrition Assessment." For example, a below-the-knee amputee loses 5.9 percent, or 0.059, of his original body weight during the amputation.
Subtract the percentage of body weight you lost from 100 to determine what percentage of body weight remains. For example, if you lost 5.9 percent of your body weight during the amputation, 94.1 percent of your body weight remains.
Divide this percentage by 100, and multiply that number by your ideal weight. For example, if your remaining body weight is 94.1 percent and your pre-amputation ideal body weight is 196 pounds, you would multiply 0.941 by 196 to get about 184 pounds. This number is your ideal body weight post-amputation.
Determine your Physical Activity coefficient, or PA, based on your activity level. If you are a woman 19 or older, assuming ideal body weight, your PA is 1.0 if you are sedentary, 1.12 if you are low active, 1.27 if you are active and 1.45 if you are very active. For men age 19 or older at their ideal weight, PA values are 1.0, 1.11, 1.25 and 1.48, respectively.
Use the Estimated Energy Expenditure equation to determine how many calories you need to consume. For men, the equation is: 662 - 9.53 X age in years + PA X (15.91 X weight in kilograms + 539.6 X height in meters). For women, the equation is: 354 - 6.91 X age in years + PA X (9.36 X weight in kilograms + 726 X height in meters). For reference, one kilogram is equal to 2.2 U.S. pounds, and one meter is equal to 3.28 U.S. feet. If you were to solve the equation for a 6-foot, 3-inch tall, 24-year-old, active, below-the-knee amputee male, you would find that he needs about 2,790 calories each day.