Calculating diet using Exchange system
To start calculating a diet plan for a patient, we need to start with determining
patient's total kcal need. This is done by using either Haris benedict formula, or quick
short cut method. In our case we will use Haris Benedict.
Ex Male 52 IF = 1.2
Wt 154 lb= 70kg AF = 1.2
Ht 5'9' = 175.36cm
HB = 66 + (13.7 + wt(kg)) + (5 x ht(cm)) - (6.8 x age)
HB = 66 + 959 + 875 - 353
HB = 1547 x 1.2 x 1.2 = 2228 = 2200kcal
When we are calculating diet plan, we distribute these kcal into three main
groups CHO, Protein , and Fat. All diets in the hospital are based on regular diet.
This diet is then divided into the above macro nutrients using certain percentage.
This % can slightly vary among different facilities and you need to find out the
exact % from your facility diet manual. In general we use this following
distribution. CHO = 50-55%
Protein = 20%
Fat = 25%
All three has to add up to 100% because that's our total kcal need.
To use our example we will now calculate grams of CHO, Protein and Fat.
2200 x .55 = 1210 kcal : 4 = 303 gm of CHO
2200 x .20 = 440 Kcal : 4 = 110 gm of Protein
2200 x .25 = 550 Kcal : 9 = 61 gm of Fat
Now we have an idea of how many grams of CHO protein and fat we can give our patient,
if his diet calls for 2200Kcal.
The next step now is to divide these grams into our six food groups
Milk
Vegetable
Fruit
Bread/starch
Meat
Fat
To do this we need to know food Guide Pyramid. The reason for that is that FGP gives
us model of varied balanced diet. We know that in FGP there are
6-11 servings in bread and cereal group
3-5 ========== vegetable group
2-4 ========== fruit group
2 ========== milk group
2-3 ========== meat group
sparingly ====== fat and sugar
This distribution provides, depending on the upper or lover number of serving from
each group, about 1600-2200 kcal
In our case we have calculated that our patient is supposed be getting 2200 Kcal
This means that we will use the upper range of servings from FGP as our guide. But it
doesn’t mean that we HAVE TO use this distribution. It is only a guide that we can
use to make it simpler. In reality we should always get as a first thing patient's
food preferences. Reason for that is that you may find out that he may not like certain
foods, or he may be allergic to some foods. Giving him these foods on menu will result in
lower kcal intake, because the patient is not going to eat either the food item itself,
or in worse scenario, will reject the entire meal.
Calculating diet
Let's start with milk group. First question that should come up to your mind is
"is he/she milk drinker or no? is she milk intolerant? What kind
of milk he/she drinks 1% or 2 %? In the hospital we usually see only these two + skim
milk and lactose free milk.
Vegetable may be another hard issue when assembling patient’s menu. There are
people who will not eat vegetable under no circumstances, and though you may have
self conscientious feeling of giving them some on their plate, this might result in
rejection of entire meal, and patient’s aggravation. Find out what vegetable he/she likes,
cooked or raw salads? In reality you can flip-flop vegetable with fruit. Usually good
number for vegetable exchanges is about 4 per day, but if that is not possible,because
patient refuses vegetable you can make up for the loss of vitamins in fruit group.
The reason for that is that it is easier to give patient fruit than vegetable. It is
because in reality patients will most likely not refuse to drink
juice that can be given with every meal. It is also a good practice to give him juice
with meals because there are number of medications that are supposed to be taken
with juice. For that reason, if you want to make up for the loss of vitamins in vegetables
(if patient refuses to eat it) give him extra fruit ( more then 4 exchanges)
After you fill up and calculate the number of exchanges and grams of CHO, Protein,
and Fat for milk, vegetable and fruit (see example below), you stop. Before you proceed
any further -the bread group- you need to add up all the grams of CHO used so far in
milk, vegetable and fruit group. This number then subtract from total grams of CHO,
determined at the beginning (50-55% of total kcal). The remaining number of grams
has to be divided by 15 which corespondents to number of grams of CHO in one
bread exchange(e.g. total CHO grams = 300gm. From milk vegetable and fruit you
got 120gm. 300-120 = 180gm. 180 : 15 = 12. 12 is the number of bread/starch exchanges.
After you fill into the table grams of CHO and protein for the bread group you
have to stop again. Now you will add up all the proteins so far given in the table.
That is add up protein from milk, vegetable, and bread groups. This number then
subtract from the total protein calculated in the beginning (20% of total kcal).
The resulting number of grams then divide by 7( there is 7 gm of protein in one
meat exchange. The number you get is the number of meat exchanges that you
plug in.
Before you can calculate the appropriate number of grams of fat in
meat group, you have to decide which meat group are you going to use.
We have very lean 0-1gm of fat, lean 3 gm of fat, medium 5 gm and high fat
8 gm of fat per exchange. Now you can either choose all meat exchanges
from one group or you can combine 2 groups e.g. half of the exchanges
(3 out of 6) from lean and second half from medium) remember that in the hospital
there is usually not the option to use high fat meats, since they are not considered
as heart healthy choices. If you choose to use 2 different meat groups you will
calculate fat grams for both separately(e.g. 3 lean exchanges = 3 x 3 = 9gm
and 3 medium exchanges = 3 x 5 = 15 grams of fat)
After you finish with meat, you have one last category left-the fat group.
To assign how many grams of fat patient will get, you have to first add all the
fat used so far. This means you will add together fat from milk and meat
groups because those are the only groups where we calculated any fat.
The number you get is then subtracted from the total fat calculated at the
beginning (25-30% of total kcal). This number is then divided by 5 since
there is 5 grams of fat in one fat exchange. Number you get is the number
of fat exchanges you will plug into the table.
To see practical example of what we just did look at the table below.
We calculated by means of Haris Benedict that the total kcal need
for our patient is 2200kcal. We have also agreed that the ratio of
CHO, Protein, and fat will be as follows
CHO = 55%
Protein = 20%
Fat = 25%
From this we can calculate how many gams is our patient getting
2200 x 0.55 = 1210 kcal : 4 = 303 gm of CHO
2200 x 0.20 = 440 kcal : 4 = 110 gm of Protein
2200 x 0.25 = 550 kcal : 9 = 61 gm of Fat
Ex CHO Protein Fat
Milk 2 24 16 5
Vegetable 5 25 10 -
Fruit 4 60 - -
Bread/st. 13 303- 109 = 194 : 15
= 13 39 -
Meat 6 - 110 - 65 = 45 : 7 18
(Lean meat) = 6
Fat 7 - - 61- 23=38
38: 5 =7
The above meal plan we need to translate now into meal pattern. To do that
you simply divide number of exchanges in every group between breakfast
lunch and dinner. It is up to you or the patient’s preferences to decide
how many servings of for example bread/starch group will this patient
get for every meal. Sample of one possible combination follows :
EX B L D
Milk 2 1 ½ ½
Vegetable 5 1 2 2
Fruit 4 2 1 1
Bread/starch 13 3 3 4 Snack 3
Meat 6 1 2 3
Fat 7 2 2 3
The last remaining step is to translate this meal pattern into real foods
To do this you need to know exchange system. An example of the
way the menu is written follows
EX B L D
Milk 2 1 cup of milk = 1 ex ½ a cup of milk = ½ ex ½ a cup of milk = ½ ex
Veg. 5 ½ cup of mixed ½ a cup of string beans 1 cup of fresh salad 1 ex
Vegetable for = 1 ½ a cup of cooked spinach
Egg omelet =1 ex ½ a cup of cooked = 1 ex
Carrots = 1 ex
In a similar fashion you will continue till you finish the whole menu Good luck.