Science · Class 9-10 · Chapter 1 · 1.3 Planning the day's food
The day's food.
Everything learnt so far, the six food components, the vitamins, the minerals, water, roughage and calories, comes together here. A balanced diet is one in which the six components and the roughage stand in the proportion the body needs. The word that matters is proportion, not quantity.
lay it outpick a meal, then tap a food
Lay out one balanced day
The calorie figures for the foods are approximate and rounded for the sake of learning; they are not the book's. Everything is worked at 4 kcal a gram for carbohydrate and protein and 9 for fat.
1. The proportion is of calories, not of weight
The book gives the proportions as percentages of the day's calories. From carbohydrate should come 50 to 60 per cent, from protein 15, from saturated fat 7, and from unsaturated fat up to 20. Notice that these are percentages of calories and not of weight, and the difference is large, because a gram of fat gives 9 kcal where a gram of carbohydrate or protein gives 4.
Added up they come to about 97. The rest comes from the vitamins, the minerals, the water and the roughage, which give no calories at all. So a large part of a balanced diet carries no energy, and it is exactly that part which is most easily left out.
the platemove the three into the book's range
The proportions on the plate
2. The food pyramid
Put the same thing as a picture and it becomes the food pyramid. Four layers from the bottom up, and the width of each layer is the whole of the message.
four layerstap a layer
The food pyramid
Rice, bread, potato, flattened rice, puffed rice. The widest layer, because the largest share of the day's calories, 50 to 60 per cent, should come from here. This is the body's chief fuel and the quickest to use.
Leafy greens, vegetables, banana, guava, mango, papaya. Few calories, and nearly all of the vitamins, the minerals and the roughage. This is the layer most easily left out, and leaving it out empties three of the six components at once.
Lentils, fish, meat, eggs, milk. The raw material for growth, for repair and for resisting disease. By the book about 15 per cent of the day's calories come from here. Plant and animal sources together make up what each lacks, as rice and lentils do.
Oil, ghee, butter. The narrowest layer, because a gram carries 9 kcal: a little gives a great deal. The book's figures are 7 per cent saturated and up to 20 unsaturated. But narrow does not mean to be dropped; vitamins A, D, E and K are not absorbed at all unless some fat is there with them.
The shape carries the rule: wide at the bottom and narrow at the top, which is to say more of what is below and less of what is above. But no layer is dropped. Without the oil at the top, vitamins A, D, E and K are not absorbed; without the vegetables on the second layer, the vitamins, minerals and roughage never arrive. The pyramid is a picture of proportion, not of prohibition.
3. Energy goes even lying still
The body does not spend energy only on work. Breathing, the beat of the heart, holding its own temperature: all of it takes energy, and it goes on whether or not anyone stirs all day. That least spending is called the basal metabolic rate. The figure the book gives is for women: about 0.9 kilocalories per kilogram of body mass, per hour.
calculatorput your own number if you like, or leave it
How much energy a day goes
The book gives two figures: a basal metabolic rate for women of 0.9 kcal per kilogram per hour, and a daily need of 2500 to 3000 kcal for an adult man. No multiplier for the day's activity is used here, the book's figure for it not having been checked.
What you type goes nowhere. The page is yours.
The basal rate is only the floor. On top of it goes the energy for the day's work, and the need shifts with age, with sex, with body mass and with how busy the day is. By the book an adult man needs about 2500 to 3000 kilocalories a day. And in the growing years the need is greater still, because then the body is not only running but building.
4. Where the gap is
Undernourishment has two faces: getting less than is needed, and getting it in the wrong proportion. The second is the commoner here; rice enough, and protein and vitamins short. Often that is not a matter of choice but of what is to be had. Tap the six lists below and see what each has and where each falls short.
read themtap one of the lists
Where the gap is
It has: carbohydrate in plenty and protein enough, and because the rice and the lentils are together, each makes up what the other lacks. The gap: no source of vitamin A or C, and no calcium. Add: a bowl of greens and a piece of fruit, and much of it is filled.
It has: nearly all six: carbohydrate from the rice, protein from the fish and the lentils, vitamin A and iron from the greens, roughage from the greens and the lentils, and water. The gap: no source of vitamin C, and little calcium. Add: a guava or a lemon, and a glass of milk or a bowl of small fish.
It has: vitamins, minerals and roughage in plenty. The gap: very little carbohydrate or protein and almost no fat, so the bulk of the energy is missing and so is the material for building. Add: rice or bread, and any one of lentils, an egg or fish.
It has: energy in plenty, both carbohydrate and fat. The gap: hardly any source of vitamins, minerals or roughage, and little protein. Calories alone do not make a diet balanced; in the book's words, getting it in the wrong proportion is undernourishment too. Add: an egg or a bowl of lentils, a bowl of vegetables, and a piece of fruit.
It has: all six: carbohydrate, protein from the egg and the milk, fat from the yolk and the cooking oil, vitamins A and D from the egg and milk, vitamin C from the fruit, calcium from the milk, roughage from the vegetables and the fruit, and water. The gap: nothing worth naming. Notice: there is nothing costly or special in it, only variety.
It has: carbohydrate, and a great deal of it; calories are not short. The gap: protein, fat, vitamins, minerals and roughage, all five near zero. The stomach is filled and three of the body's four jobs, growth, resistance and repair, go unserved. Add: a bowl of lentils and a bowl of greens; those two change a great deal.
All six. Notice that every one of them has something; the question is only what is missing and what would fill it. The shape of an answer is those same three: what it has, where the gap is, and what to add.
check yourself
One question
A day's food: parota and a fried vegetable in the morning, rice and fried potato at midday, rice and potato curry at night. What is chiefly wrong with the list?
Calories are not short; the parota, the rice, the oil and the potato bring energy enough. The shortage is elsewhere.
Right. There is carbohydrate and fat enough, so calories are not the trouble; the stomach fills and the energy comes. But there are no lentils, no fish, no egg and no milk, so protein is near zero; and no greens, vegetables or fruit, so the vitamins, minerals and roughage are missing too. In the book's words, eating in the wrong proportion is undernourishment as much as eating too little. A bowl of lentils and a bowl of greens would bring the list a long way back into balance.
If anything there is a great deal of it; the rice, the parota and the potato are all starches.
Water is not mentioned in the list at all, and too much of it is not the question here.
5. Keeping the numbers to hand
What this section can be examined on is seven numbers, and all three of the widgets above have used them.
cardstap a card
Seven numbers
number৫০-৬০%
what it isThe share of the day's calories that should come from carbohydrate.
number১৫%
what it isThe share that should come from protein.
number৭%
what it isThe share from saturated fat, at most.
number২০% পর্যন্ত
what it isThe share that may come from unsaturated fat.
number২৫০০-৩০০০ kcal
what it isThe daily energy an adult man needs.
number০.৯ kcal
what it isThe basal metabolic rate for women, per kilogram of body mass, per hour.
numberFour layers
what it isIn the food pyramid, from the bottom: the starches, vegetables and fruit, the protein foods, fats and oils.
check yourself
Another question
By the book, what share of the day's calories should come from carbohydrate?
Fifteen per cent is the protein's share, not the carbohydrate's.
Up to 20 is the share of unsaturated fat.
Right. Carbohydrate is the body's chief fuel, so the largest share of the day's calories should come from it, which the book puts at 50 to 60 per cent. Fifteen is the protein's share, and 7 and up to 20 belong to the fats. It is why the starches are the base of the pyramid and the oil is its top.
At 80 there would be almost nothing left for the rest; the book's range is 50 to 60.
check yourself
Last question
At a basal rate of 0.9 kcal per kilogram per hour, how much energy does a 50 kg girl spend in a day simply staying alive?
Forty five is the spending in one hour. The question asks for a day, so it has to be multiplied by 24.
Right. The rate is given per kilogram and per hour, so both have to be multiplied in. Fifty kilograms × 0.9 kcal = 45 kcal an hour; a day has 24 hours, so 45 × 24 = 1080 kcal. And that 1080 goes even lying still all day, on the breathing, the heartbeat and the holding of the body's temperature alone. Add the day's work and the need goes higher.
Twelve hundred is a round number but not this sum. Fifty × 0.9 × 24 = 1080.
Two and a half to three thousand is the book's daily need for an adult man, not a basal calculation.
At a glance
A balanced diet. One in which the six components and the roughage stand in the proportion the body needs.
The shares of the calories. Carbohydrate 50 to 60%, protein 15, saturated fat 7, unsaturated up to 20. The vitamins, the minerals, the water and the roughage give no calories and must be there all the same.
The pyramid. From the bottom: the starches, vegetables and fruit, the protein foods, fats and oils. Wide below and narrow above, and no layer left out.
Energy. The basal metabolic rate for women is 0.9 kcal per kilogram per hour. An adult man's daily need is about 2500 to 3000 kcal.
The two faces of undernourishment. Getting less than is needed, and getting it in the wrong proportion.
If your body or your eating is worrying you, talk to an older person at home or to a teacher at school; if it is needed they will take you to a doctor.
Source: Science, Classes 9-10 (NCTB), Chapter 1 “A better way of living”, section 1.3. The calorie and gram figures on the board are approximate and not the book's, and no activity multiplier is used in this note.