Diet Imbalance & Deficiency
Explain how dietary imbalance can affect health: repeated energy surplus can increase body fat, severe energy shortage can cause starvation, and too little of a nutrient can cause a deficiency disease such as scurvy or rickets
What a learner can do afterwards
- Defines obesity, starvation, and deficiency disease and links each to dietary imbalance
- Links scurvy to too little vitamin C and rickets to too little vitamin D or calcium
- Explains why the impact of poor diet can be long-term
1 · Read
A healthy diet supplies energy and nutrients. Extra energy can be stored as fat when intake repeatedly exceeds use. Obesity means excess body fat that can harm health. Genes, health conditions and living conditions also affect its development. To read an energy chart, compare intake with use. If intake is higher, subtract use from intake to find the surplus. One day's chart cannot diagnose obesity.
Starvation is a severe shortage of food energy. During a prolonged shortage, the body uses stored fuel and breaks down body tissues, including muscle. Growth, repair and organ function can suffer. Starvation needs medical care. Missing one meal is not the same as starvation.
A deficiency disease results from too little of a nutrient, even if food energy is enough. Vitamin C helps make collagen, which supports body tissues. Too little vitamin C can cause scurvy, with bleeding gums and slow wound healing. Vitamin D helps the body absorb calcium. Too little vitamin D or calcium can cause rickets in children: growing bones stay soft and may bend. Symptoms need medical assessment.
Stores of some nutrients can support the body for a while, so a deficiency may take weeks or months to show symptoms. Damaged tissues may also take time to heal after the nutrient supply is restored. Obesity raises the risk of conditions such as heart disease and type 2 diabetes. Effects and recovery time vary. People with these conditions need care, not blame.
To total a repeated surplus, multiply the daily extra energy by the number of days. In an example, 300 kJ extra each day for 4 days gives 300 × 4 = 1200 kJ. This totals energy only. It does not predict an exact weight change or give a diagnosis.
Repeated energy surplus can increase body fat. Severe energy shortage can cause starvation. Missing nutrients can cause deficiency diseases, even with enough energy.
Lesson, questions and study cards written for this dataset.
Readings and study cards written for this dataset. Linked TED-Ed videos: How to spot a fad diet by Mia Nacamulli and Is it possible to lose weight fast? by Hei Man Chan.
More to read
Energy and nutrients answer different questions
An energy total tells you how much energy food supplies. It does not list all the vitamins and minerals in that food.
Suppose someone gets enough food energy but very little vitamin C for months. More energy would not replace the missing vitamin. The person could still develop scurvy.
A different diet might contain varied foods but provide far too little energy overall. A severe, prolonged shortage can lead to starvation. To understand a diet, consider both its energy supply and the nutrients it provides.
Why missing nutrients have different effects
Vitamin C helps the body make collagen, a material that supports tissues. A prolonged shortage can cause scurvy. Possible signs include bleeding gums and slow wound healing.
Growing bones need calcium. Vitamin D helps the body absorb it. Too little vitamin D or calcium can cause rickets in children, leaving growing bones soft and sometimes bent.
The missing nutrient matters because nutrients have different jobs. These links explain possible causes of illness. They do not let you diagnose a person from one symptom. Medical assessment is needed.
A shortage and its symptoms may begin at different times
The body has stores of some nutrients. If intake becomes too low, those stores can support the body for a while. Symptoms may appear only after the shortage has continued.
Restoring the nutrient supply does not instantly repair every damaged tissue. Healing can take time, and recovery varies with the nutrient, the damage and the person.
Obesity raises the long-term risk of conditions such as heart disease and type 2 diabetes. Increased risk does not mean that every person with obesity will develop those conditions.
An energy chart is not a diagnosis
Compare the energy-intake bar with the energy-use bar. Intake above use shows a surplus. When a surplus repeats over time, stored body fat can increase.
That does not make one day's chart a medical test. It does not show the person's usual nutrient intake or all the factors affecting their health. Genes, health conditions and living conditions also affect how obesity develops.
Multiplying a daily surplus by a number of days gives a total surplus. It does not give an exact change in body mass. Classroom values are examples, not personal eating targets.
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