Malnutrition is a condition that occurs when a person does not receive the right amount of nutrients, such as vitamins and minerals, from their diet.

These nutrients are essential for healthy growth and activity. An imbalanced or poor diet can lead to either an excess or a deficiency of specific nutrients.

Obesity and starvation

Energy is measured in joules. However, on food packaging, the energy in food is often listed in calories (kcal).

  • 1 calorie (kcal) = 4.184 kilojoules (kJ)

The daily recommended calorie intake is 2,000 for women and 2,500 for men. However, it’s important to remember that these are just guidelines; individual needs may vary based on factors like height and activity level. An imbalanced diet occurs when the energy gained from food doesn’t match the energy you need.

  • Consuming too little food may lead to starvation
  • Consuming too much food may lead to obesity

Being either underweight or overweight poses significant health risks. Being underweight can lead to a weak immune system and being obese can increase the chance of heart disease. Also, not consuming the right amount of each vitamin and mineral can result in long-term health problems.


Maintaining a healthy weight is important for your overall well-being. BMI (Body Mass Index) uses a person’s height and weight to determine if their weight is healthy. The equation is:

The formula for calculating Body Mass Index (BMI). It is represented as 'BMI' equals 'Weight' in kilograms divided by 'Height' in metres squared.

For example, if a person weighs 70 kg and has a height of 1.80 m:

BMI = 70 kg ÷ 1.80²

BMI = 21.6 kg/m²

The table below shows the BMI categories. So, individuals with a body mass over 30 are considered to be obese.

Healthy weight18.5 to <25
Overweight25 to <30


A deficiency means that you don’t have enough of a particular vitamin or mineral.

Mineral deficiencies

Minerals are essential nutrients that our bodies need in small amounts to function properly. A lack of certain minerals can lead to deficiencies, such as:

  • Iron deficiency – Can cause anaemia, a condition in which there are not enough red blood cells to transport oxygen to the body’s tissues.
  • Iodine deficiency – Can cause goitre, a swelling in the neck caused by an enlarged thyroid gland.

Vitamin deficiencies

Similarly, a lack of certain vitamins can also lead to deficiencies:

  • Vitamin A deficiency – May lead to blindness.
  • Vitamin C deficiency – Can cause scurvy, which makes the gums bleed.
  • Vitamin D deficiency – Can cause rickets, a condition that causes weak bones and deformities in growing children.