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 required for healthy growth and activity. An imbalanced or poor diet can contain too much or too little of a particular nutrient and may even lead to a deficiency.

Obesity and starvation

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

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

The daily recommended calorie intake for women is 2,000 and 2,500 for men. However, it is important to remember that this is just a guide and we are all different. Your recommended daily calorie intake differs based on factors such as height and how active your lifestyle is. If the amount of energy obtained from food is different from the amount of energy needed, then the diet is imbalanced.

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

Being either underweight or overweight may eventually lead to death. This is because being underweight can lead to a weak immune system and being obese increases the chance of heart disease. Also, eating the right amount of each vitamin and mineral is essential. Not consuming the right amount can lead to long-term health problems.


Maintaining a healthy weight is important for your overall health. BMI (Body Mass Index) uses the height and weight of a person to work out if their weight is healthy. The equation is:

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

BMI = 70 kg ÷ 1.80²

BMI = 22.5 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


Having a vitamin or mineral deficiency means that you do not 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 a deficiency. Some examples are:

  • 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

Vitamins are also essential nutrients that our bodies need in small amounts to function properly. A lack of certain vitamins can lead to a deficiency. Some examples are:

  • Vitamin A deficiency – Can 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.