Components of a Balanced Diet

Diet and nutrition are a key part of the OCR GCSE PE (J587) specification. You must understand the components of a balanced diet, the role each nutrient plays in the body, and how diet affects health and performance. This lesson covers the seven components of a balanced diet that OCR requires you to know.

---

What Is a Balanced Diet?

A balanced diet is one that contains the right amount of each nutrient to meet the body's needs. It should include a variety of foods from different food groups, providing energy for physical activity, materials for growth and repair, and substances for maintaining body functions.

Key Principle	Detail
Variety	Eating a range of different foods ensures all nutrient needs are met
Proportion	Eating the right amounts of each food group — more of some, less of others
Moderation	Not eating too much of any one food type, especially those high in fat, sugar or salt

---

The Seven Components of a Balanced Diet

1. Carbohydrates

Carbohydrates are the body's primary source of energy, especially during physical activity.

Type	Found In	Role
Simple carbohydrates (sugars)	Fruit, sweets, sugary drinks, honey, jam	Provide quick-release energy — rapidly absorbed into the bloodstream
Complex carbohydrates (starches)	Bread, pasta, rice, potatoes, cereals, oats	Provide slow-release energy — digested and absorbed gradually, sustaining energy over a longer period

Key Fact	Detail
Stored as glycogen	Excess carbohydrates are converted to glycogen and stored in the muscles and liver
Glycogen → glucose	During exercise, glycogen is converted back to glucose to provide energy for muscle contractions
Excess stored as fat	If glycogen stores are full, additional carbohydrates are converted to fat
Recommended intake	Approximately 50–60% of total calorie intake should come from carbohydrates

Exam Tip: OCR examiners frequently ask about the difference between simple and complex carbohydrates. Remember: simple = quick energy (sugars); complex = slow, sustained energy (starches). For endurance sports, complex carbohydrates are preferred because they provide sustained energy release.

2. Proteins

Proteins are essential for growth and repair of body tissues, especially muscle.

Role	Detail
Muscle growth and repair	After exercise, protein helps repair damaged muscle fibres and build new muscle tissue
Enzyme production	Proteins form enzymes that control chemical reactions in the body
Hormone production	Some hormones (e.g. insulin) are made from protein
Immune system	Antibodies that fight infection are proteins
Energy source (secondary)	Protein can be used for energy if carbohydrate and fat stores are depleted, but this is not its primary role

Source Type	Examples
Animal sources	Meat, fish, eggs, dairy products
Plant sources	Beans, lentils, nuts, tofu, quinoa

Recommended intake: approximately 15–20% of total calorie intake.

3. Fats

Fats are a concentrated source of energy and play several important roles in the body.

Type	Found In	Health Impact
Saturated fats	Butter, cheese, fatty meat, cakes, biscuits	Raise LDL ("bad") cholesterol; increase CHD risk if consumed in excess
Unsaturated fats	Olive oil, nuts, avocado, oily fish	Lower LDL cholesterol and raise HDL ("good") cholesterol; beneficial for heart health

Role of Fats	Detail
Energy source	Fats provide more energy per gram than carbohydrates (9 kcal/g vs 4 kcal/g); used mainly during low-intensity, long-duration exercise
Insulation	A layer of fat beneath the skin helps maintain body temperature
Protection of organs	Fat cushions vital organs such as the kidneys and heart
Absorption of vitamins	Fat-soluble vitamins (A, D, E, K) can only be absorbed with dietary fat
Cell membranes	Fats are a key structural component of every cell in the body

Recommended intake: no more than 30–35% of total calorie intake, with a preference for unsaturated over saturated fats.

4. Vitamins

Vitamins are micronutrients needed in small amounts for a wide range of body functions.