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.

Vitamin	Key Role	Food Sources	Deficiency Consequence
Vitamin A	Vision, immune function, skin health	Carrots, sweet potato, liver, eggs	Poor night vision, weakened immune system
Vitamin B group	Energy release from food, red blood cell production, nervous system function	Meat, fish, eggs, whole grains, green vegetables	Fatigue, anaemia, poor energy levels
Vitamin C	Immune function, skin health, wound healing, absorption of iron	Citrus fruits, peppers, strawberries, broccoli	Scurvy (bleeding gums, slow wound healing), weakened immunity
Vitamin D	Calcium absorption, bone health, immune function	Sunlight, oily fish, eggs, fortified cereals	Weak bones (rickets in children, osteomalacia in adults)

Exam Tip: You do not need to know every vitamin in detail for OCR GCSE PE, but you should be able to name at least two vitamins, their roles and their food sources. Vitamin C and Vitamin D are the most commonly examined.

5. Minerals

Minerals are inorganic micronutrients essential for specific body functions.

Mineral	Key Role	Food Sources	Deficiency Consequence
Calcium	Bone and teeth formation, muscle contraction, blood clotting	Dairy products, green leafy vegetables, fortified bread	Weak bones, osteoporosis, muscle cramps
Iron	Haemoglobin formation (carries oxygen in red blood cells)	Red meat, spinach, beans, fortified cereals	Anaemia (fatigue, reduced oxygen transport, poor endurance)
Sodium	Nerve function, muscle contraction, fluid balance	Salt, processed foods, bread, cheese	Muscle cramps, dizziness (but excess sodium raises blood pressure)

Key Mineral for PE	Why It Matters
Calcium	Essential for bone density — directly relevant to preventing osteoporosis and supporting the skeletal system during exercise
Iron	Essential for oxygen transport — iron-deficient athletes have reduced cardiovascular endurance

6. Fibre

Fibre is a type of carbohydrate that the body cannot digest. Despite not providing energy, it plays a vital role in digestive health.

Role	Detail
Aids digestion	Fibre adds bulk to food, helping it move through the digestive system efficiently
Prevents constipation	By absorbing water and adding bulk, fibre keeps bowel movements regular
Reduces cholesterol	Soluble fibre helps lower blood cholesterol levels
Regulates blood sugar	Fibre slows the absorption of sugar, preventing spikes in blood glucose
Promotes satiety	High-fibre foods help a person feel full for longer, reducing the temptation to overeat

Good sources: whole grains, vegetables, fruit, beans, lentils, nuts, seeds.

7. Water and Hydration

Water is essential for almost every bodily function and is particularly important during physical activity.

Role of Water	Detail
Temperature regulation	Sweating releases heat from the body; sweat is primarily water
Transport of nutrients	Blood (which is mostly water) carries oxygen and nutrients to working muscles
Removal of waste	Water helps flush metabolic waste products (e.g. carbon dioxide, lactic acid) from the body
Joint lubrication	Synovial fluid in joints requires adequate hydration to function effectively
Chemical reactions	Many metabolic reactions require water as a medium

Dehydration Level	Effects
Mild (1–2% body mass loss)	Thirst, reduced concentration, slight performance decline
Moderate (3–5% body mass loss)	Headache, dizziness, significant performance decline, muscle cramps
Severe (6%+ body mass loss)	Confusion, rapid heartbeat, fainting, heat stroke — life-threatening