The science of nutrition and healthy eating
The science of nutrition and healthy eating

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The science of nutrition and healthy eating

3.3 Calculating RIs

In the next activity you will practise working out reference intake values.

Activity 4 Calculating daily intake

Allow approximately 10 minutes.

1) If a pack of sandwiches contains 7 g of fat, of which 6 g is saturated fat, what percentages of the total fat and the saturated fat are these for the day?

Remember that, to calculate the percentage, you need to divide the number of grams of fat in the sandwich by the RI value before multiplying the result by 100.

a. 

a) they are each 86% of the fat for the day


b. 

b) the sandwiches contain just under 9% of the total fat and 10% of the saturated fat


c. 

c) the sandwiches contain 10% of the total fat and 65% of the saturated fat


d. 

d) the sandwiches contain 10% of the total fat and 30% of the saturated fat


The correct answer is d.

d. 

Correct: Because the RI for total fat is 70 g, and the sandwiches contain 7 g, then calculating 7/70 and multiplying by 100, shows that the sandwiches contain 10% of the total fat for the day.

The RI for saturated fat is 20 g and the sandwiches contain 6 g, so a similar calculation (6/20, multiply by 100) shows that the sandwiches contain 30% of the saturated fat for the day. You may find 5.3.2 Reference intake values useful.


2) Consider the data in Table 3 for a chocolate and caramel snack bar.

Table 3 Nutrients and kilocalories in a 100 g snack bar

Energy or nutrient Reference intake
Calories 448 kcal
Carbohydrate 68.1 g
Protein 4.2 g
Fat 17.4 g
Fibre 1.1 g
Calories in a chocolate and caramel snack bar (62.5 g): 280.6 kcal
  • What is the most number of bars that a person could eat without exceeding the daily RI of 2000 calories (kcal)?
  • How much fat would they consume if they ate those bars?

a. 

a) they could eat 4 bars and would consume close to the RI of fat for a day


b. 

b) they could eat 5 bars and would consume just over the RI of fat for a day


c. 

c) they could eat 7 bars and would consume slightly more than the RI of fat for a day


d. 

d) they could eat 7 bars and would consume more than 50 g over the RI of fat for a day.


The correct answer is c.

c. 

Correct: Because one bar weighs 62.5 g, the amount of calories in one bar is about 280. The maximum number of bars that would provide a calorie count of less than 2000 is 2000 division 280, which gives more than 7 bars, but less than 8. Each bar contains just over 10 g of fat (there are 17.4 g of fat in 100 g of the bar), so 7 bars would contain just over the RI value advice for fat of 70 g. You may find 5.3.2 Reference intake values useful.


SNHE_1

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