Big picture
Food is the fuel for every movement an athlete makes. A sprinter, a footballer and a marathon runner all need the right mix of nutrients in the right amounts at the right times to train hard, perform well and recover. Poor nutrition leads to fatigue, injuries and illness.
This chapter explains what a balanced diet is, the functions and sources of each nutrient, how to control weight healthily, and common mistakes and myths about food.
Learning goals
Explain nutrition and a balanced diet.
Describe macronutrients and micronutrients, with their sources and functions.
Distinguish nutritive and non-nutritive components of diet.
Explain eating for weight control and the meaning of a healthy weight.
Explain the pitfalls of dieting, food intolerance and food myths.
Core ideas
1. Nutrition and balanced diet
Nutrition is the process by which the body takes in and uses food for energy, growth, repair and maintenance.
Nutrients are substances in food that the body needs: carbohydrates, proteins, fats, vitamins, minerals and water.
A balanced diet contains all the nutrients in the right proportion to meet the body's needs, according to age, gender, body size, activity level and climate.
For an athlete, a common guide is about 55–60% of energy from carbohydrates, 12–15% from proteins and 25–30% from fats.
2. Macronutrients
Macronutrients are needed in large amounts and provide energy (except water).
Nutrient | Energy | Functions | Sources |
|---|---|---|---|
Carbohydrates | 4 kcal per gram | The main source of energy, especially for intense exercise; stored as glycogen in muscles and the liver | Cereals (rice, wheat), potatoes, sugar, fruits, bread, honey |
Proteins | 4 kcal per gram | Growth and repair of tissues and muscles; make enzymes, hormones and antibodies; called the building blocks of the body | Milk, eggs, meat, fish, pulses, soybean, nuts, paneer |
Fats | 9 kcal per gram | A concentrated source of energy, especially for long, low-intensity exercise; carry fat-soluble vitamins (A, D, E, K); insulate and protect organs | Butter, ghee, oils, nuts, cheese, meat |
Types of carbohydrates: simple (glucose, fructose, sucrose: quick energy) and complex (starch, fibre: slow, sustained energy).
Types of fats: saturated (solid at room temperature; animal fats, ghee; excess raises cholesterol) and unsaturated (liquid; vegetable oils, nuts, fish oil; healthier).
3. Micronutrients
Micronutrients are needed in small amounts but are essential.
Vitamins:
Vitamin | Functions | Sources | Deficiency |
|---|---|---|---|
A (fat-soluble) | Vision, healthy skin, immunity | Carrots, green leafy vegetables, milk, eggs, fish liver oil | Night blindness |
D (fat-soluble) | Absorption of calcium; strong bones and teeth | Sunlight, milk, eggs, fish | Rickets (children), osteomalacia (adults) |
E (fat-soluble) | Antioxidant; protects cells | Vegetable oils, nuts, green vegetables | Weakness, reproductive problems |
K (fat-soluble) | Blood clotting | Green leafy vegetables, soybean | Excessive bleeding |
B-complex (water-soluble) | Energy release from food, healthy nerves | Whole grains, pulses, eggs, meat, milk | Beriberi (B1), pellagra (B3), anaemia (B12) |
C (water-soluble) | Healthy gums, wound healing, immunity, iron absorption | Citrus fruits, amla, tomatoes, guava | Scurvy |
Minerals:
Mineral | Functions | Sources | Deficiency |
|---|---|---|---|
Calcium | Strong bones and teeth, muscle contraction, blood clotting | Milk, curd, cheese, green leafy vegetables | Weak bones, osteoporosis, rickets |
Iron | Forms haemoglobin, which carries oxygen in blood | Green leafy vegetables, jaggery, meat, eggs, dates | Anaemia |
Iodine | Forms thyroid hormones | Iodised salt, seafood | Goitre |
Sodium and potassium | Fluid balance, nerve and muscle function; lost in sweat | Salt, bananas, fruits | Muscle cramps |
Phosphorus | Bones and teeth, energy metabolism | Milk, meat, cereals | Weak bones |
Water: makes up about 60% of body weight; regulates body temperature (sweating), transports nutrients and removes waste. Athletes must drink water before, during and after exercise; a loss of even about 2% of body weight as water reduces performance.
4. Nutritive and non-nutritive components of diet
Nutritive components | Non-nutritive components |
|---|---|
Provide energy or nutrients: carbohydrates, proteins, fats, vitamins, minerals | Don't provide nutrients or energy but are present in food |
Roughage (dietary fibre): prevents constipation, aids digestion, gives a feeling of fullness; found in whole grains, fruits, vegetables | |
Water (essential but provides no energy) | |
Colour, flavour and preservative compounds, and plant compounds (such as polyphenols) |
5. Eating for weight control
Weight control depends on energy balance: energy intake (food) versus energy expenditure (basal metabolism + physical activity).
Positive energy balance (intake > expenditure) leads to weight gain; negative energy balance leads to weight loss.
About 7,700 kcal of energy corresponds to roughly 1 kg of body fat. So a deficit of 500 kcal a day leads to a loss of about 0.5 kg a week.
Healthy weight: a weight appropriate for a person's height and body composition, usually judged by BMI 18.5–24.9, along with healthy body-fat percentage and waist size.
Tips for healthy weight control:
Eat a balanced diet with plenty of vegetables, fruits, whole grains and lean proteins.
Eat at regular times; don't skip breakfast.
Reduce sugar, fried and processed foods; control portion sizes.
Drink enough water.
Exercise regularly, combining aerobic and strength training.
Aim for slow, steady weight loss (about 0.5–1 kg a week).
6. Pitfalls of dieting
Crash dieting (very low calorie intake) causes loss of muscle and water, not just fat, and lowers metabolism.
Skipping meals leads to overeating later and low energy.
Cutting out entire food groups (such as all carbohydrates or fats) causes nutrient deficiencies.
Not drinking enough water and relying on diet pills or laxatives.
Unrealistic goals lead to frustration and the yo-yo effect (losing and regaining weight).
Extreme dieting may lead to eating disorders such as anorexia and bulimia.
7. Food intolerance
Food intolerance is difficulty in digesting a particular food, causing discomfort such as bloating, gas, stomach pain or diarrhoea. It is not an immune reaction (unlike a food allergy).
Examples: lactose intolerance (inability to digest milk sugar because of a lack of the enzyme lactase), gluten sensitivity (wheat, barley), and intolerance to caffeine or food additives.
Management: identify and avoid or limit the food, use substitutes (lactose-free milk), and consult a doctor or dietitian.
8. Food myths
Myth | Fact |
|---|---|
Eating more protein builds more muscle | Muscle is built by training with enough protein; excess protein isn't stored as muscle |
Skipping meals helps lose weight | It slows metabolism and leads to overeating |
All fats are bad | Unsaturated fats are healthy and necessary |
Drinking water during exercise causes cramps | Proper hydration prevents cramps and fatigue |
Carbohydrates make you fat | Excess total calories cause weight gain; carbohydrates are the main fuel for athletes |
Sweating more burns more fat | Sweating mainly loses water, regained when you drink |
9. Meals for competition
Pre-competition meal: eaten 3–4 hours before; high in carbohydrates, moderate protein, low in fat and fibre, easily digestible, with plenty of fluids.
During competition: water and sports drinks for events lasting over an hour.
Post-competition meal: within about 30 minutes to 2 hours; carbohydrates to refill glycogen, proteins to repair muscles, and fluids and electrolytes.
Carbohydrate loading before endurance events increases glycogen stores.
A reliable approach to questions
Define nutrition and balanced diet, with the proportions of macronutrients.
For each nutrient, give function, sources and deficiency.
Distinguish nutritive and non-nutritive components.
Explain weight control through energy balance, with the 7,700 kcal per kg rule.
List pitfalls of dieting, and explain food intolerance with lactose intolerance as an example.
Correct food myths with facts.
Connections that matter
Children and women in sports discusses eating disorders in the female athlete triad.
Yoga for lifestyle disease prevention discusses obesity and diabetes.
Biology: human health and disease explains deficiency diseases.
Common mistakes
Saying fats and carbohydrates give equal energy. Fats give 9 kcal/g; carbohydrates and proteins give 4 kcal/g.
Calling roughage a nutrient that gives energy. It is non-nutritive.
Confusing food intolerance with food allergy.
Saying vitamin C deficiency causes rickets. Rickets is due to vitamin D deficiency; scurvy is due to vitamin C deficiency.
Revision checklist
I can explain nutrition and a balanced diet.
I can give the functions, sources and deficiencies of macro- and micronutrients.
I can distinguish nutritive and non-nutritive components.
I can explain weight control, healthy weight and pitfalls of dieting.
I can explain food intolerance and correct common food myths.