Nutrition and Health · Food and Human Nutrition

Importance of proper nutrition

Good nutrition gives energy for work and play, allows normal growth, builds a strong immune system, helps in learning, lowers the risk of diseases such as obesity, heart disease, diabetes and some cancers, and helps wounds to heal. Poor nutrition (too little or too much) causes illness.

Diet, health and physical activity

A healthy diet is balanced, has variety and moderation, with plenty of fruits, vegetables, whole grains and pulses, limited sugar, salt and fat, and enough water (6–8 glasses a day). Regular physical activity (at least 30 minutes a day for adults and 60 for children) keeps the body fit and uses energy. The energy taken in should equal the energy used.

Body mass index (BMI)

BMI is used to see if an adult has a healthy weight.

BMI	Category
Below 18.5	Underweight
18.5–24.9	Healthy weight
25–29.9	Overweight
30 or more	Obese

Worked exampleCalculate BMI

A woman weighs 66 kg and is 1.65 m tall. Find her BMI.

Square the height.
Divide.

Answer: BMI = 24.3: healthy weight.

BMI rises with weight; the healthy range is 18.5 to 24.9.

Try itBMI calculator

Choose the mass and height.

Eating disorders

Disorder	Features	Risks
Anorexia nervosa	Refusing food from a fear of gaining weight, though very thin	Very low weight, weak heart and bones
Bulimia nervosa	Eating large amounts and then vomiting or using laxatives	Damaged teeth and throat, mineral imbalance
Binge-eating disorder	Frequent over-eating with a feeling of loss of control	Obesity, diabetes

Eating disorders are mental health conditions and need support from family, teachers and health workers. Treatment includes counselling, regular balanced meals and medical care.

Check yourself A BMI of 27 is

Check yourself Anorexia nervosa is

Check yourself For health, energy taken in should be

Key terms

BMI: Body mass index: mass divided by height squared.
Obesity: Having too much body fat.
Eating disorder: An unhealthy pattern of eating linked to mental health.
Physical activity: Movement that uses energy.

Summary

Good nutrition supports growth, energy and defence against disease.
A healthy diet is balanced and varied; be active every day.
BMI = mass ÷ height²; 18.5–24.9 is healthy.
Eating disorders need care and support.