Nutrition is the study of how food and drink affect our bodies with special regard to the essential nutrients necessary to support human health. It looks at the physiological and biochemical processes involved in nourishment and how substances in food provide energy or are converted into body tissues. 

The exact makeup of a diversified, balanced and healthy diet will vary depending on individual characteristics:

• age & gender, 

• lifestyle & degree of physical activity,

• cultural context & locally available foods

• and dietary customs. 

However, the basic principles of what constitutes a healthy diet remain the same. 

• Energy intake (calories) should be in balance with energy expenditure. 

• To avoid unhealthy weight gain, total fat should not exceed 30% of total energy intake. Intake of saturated fats should be less than 10% of total energy intake, and intake of trans-fats less than 1% of total energy intake, with a shift in fat consumption away from saturated fats and trans-fats to unsaturated fats, and towards the goal of eliminating industrially-produced trans-fats.

• Limiting the intake of free sugars to less than 10% of total energy intake is part of a healthy diet. A further reduction to less than 5% of total energy intake is suggested for additional health benefits.

• Keeping salt intake to less than 5g per day (equivalent to sodium intake of less than 2g per day) helps to prevent hypertension, and reduces the risk of heart disease and stroke in the adult population."

Healthy diet (who.int) May 2022