Consequences of an unbalanced diet

Define malnutrition.
Understand how energy in food is measured (kilocalories, kilojoules) and identify factors that influence an individual's energy requirements.
Describe the potential health consequences of eating too little energy (underweight, starvation), eating too much energy (overweight, obesity), and lacking specific vitamins or minerals (deficiency diseases).

Eating a balanced diet with the right amount of energy and nutrients is vital for health.
When this balance is wrong, it's called malnutrition.
An unhealthy diet can mean eating too little, too much, or not enough essential nutrients, all of which can lead to serious health problems.
Your energy needs vary depending on your lifestyle and stage of life.

All your activities, even sleeping, require energy.
This energy comes from the carbohydrates, fats, and proteins in your food.
Energy in food is measured in kilocalories (kcal), joules (J) or kilojoules (kJ) (1000 joules). Food labels often show how much energy is in a serving.
The amount of energy you need isn't fixed. It depends on several factors:
- Age: Growing children and teenagers need more energy for their size.
- Body Size: Larger people generally need more energy.
- Activity Level: The more active you are, the more energy you burn. An office worker needs less energy than a construction worker or athlete.
- Gender: On average, males need more energy than females, particularly after puberty.
There are general guidelines called Reference Intakes (RIs) for the average amount of energy an adult or child needs. For example, in the UK, a common guideline for:
- An average adult woman is around 2000 kcal (8400 kJ) per day.
- An average adult man is around 2500 kcal (10500 kJ) per day.

If you eat less energy than your body uses, you lose weight as your body starts using its own fat and muscle for energy. Severe lack of food is called starvation.
Being underweight can lead to:
1. Feeling tired and weak.
2. A weakened immune system (more likely to get ill).
3. Deficiency diseases if specific vitamins or minerals are missing.

If you consistently eat more energy (especially from fats and sugars) than your body uses, the excess energy is stored as fat.
This leads to weight gain and can result in being overweight or, if severely overweight, obese.
Obesity increases the risk of serious health problems, including:
- Heart disease
- Stroke
- Type 2 diabetes
- Some types of cancer

Even if you eat enough energy, you can still be malnourished if your diet lacks specific vitamins or minerals. This is called a deficiency.
Examples:
- Vitamin A deficiency: Can cause problems seeing in dim light (night blindness).
- Vitamin D deficiency (often linked with lack of calcium): Can lead to weak bones (a condition called rickets in children).

Malnutrition: A condition caused by eating a diet in which nutrients are either not enough or are too much, or are in the wrong proportions.
Energy: The capacity to do work, obtained from the carbohydrates, fats, and proteins in food.
Kilocalories (kcal): A common unit used to measure the energy content of food.
Kilojoules (kJ): Another unit used to measure the energy content of food (1 kJ = 1000 joules).
Underweight: Having a body weight considered too low for one's height, often due to insufficient energy intake.
Obesity: A state of being severely overweight, often due to consuming consistently more energy than the body uses.
Deficiency: A lack of a specific nutrient, such as a vitamin or mineral.
Deficiency diseases: Illnesses caused by a lack of specific vitamins or minerals in the diet.

Analyse the nutritional information on food labels to compare the energy content and key nutrients in different foods.
Research other examples of specific vitamin or mineral deficiency diseases (beyond those mentioned) and their symptoms, such as scurvy (Vitamin C) or anaemia (Iron).