How are people in comas kept alive? How are they eating?
They typically have a feeding tube, a tube that is inserted through the nose, stomach, or intestinal tract which is attached to a bag or bottle of formula. The formula is a precise mixture of water, carbohydrates, protein, fats, vitamins, minerals & sometimes fiber.
Part of a Registered Dietitian's job is to calculate the nutritional needs for individuals requiring tube feedings & to make recommendations for the recipe & rate of the formula to be administered. Each nutritional recommendation is different, based off the needs of the individual. Patients require different amounts of calories, macro & micronutrients due to varying conditions, diagnoses, & past medical history.
In a way, people requiring tube feedings are the most compliant patients dietitians can have.
If we want to control blood sugars, we can alter the amount of carbohydrates in the recipe & change the amount of formula given at one time. Same goes for weight, if we want them to gain or lose weight, we alter their calories over an extended period of time & document the weight trends.
I've worked in hospitals & long term care facilities making nutritional recommendations for individuals requiring tube feedings. The hospital was typically short term for patients, making it difficult to track progress. Working in long term care, I was able to watch patients progress with nutrition recommendations over months. Since it was controlled & consistent, I was able to watch individuals lose weight over time, based off the amount of calories given in formula.
Now, if we could turn that formula into food & help individuals with consistency.....
There are multiple formulas for figuring out how many calories you would require to maintain your current weight; Harris Benedict, Cunningham, Penn State, Mifflin St Jeor, etc. A quick method would be to take your current weight in pounds & divide by 2.2 (to convert to kilograms) & multiply that number by 25.