Physical activity level and energy needs are important when explaining why people choose different foods and portion sizes. Someone who is very active may need more energy from food than someone who is mostly sedentary, meaning they do little physical activity. However, food choice is not based on activity alone. Age, growth, body size, health, culture, cost and personal preference can also influence choices. For GCSE Food Preparation and Nutrition, you should be able to link a person’s activity level to their energy requirement and explain how this could affect the foods, meals and portions they select.
What is an energy requirement?
An energy requirement is the amount of energy a person needs from food and drink to keep their body functioning and support their daily activities. Energy is commonly measured in kilocalories, written as kcal, or kilojoules, written as kJ.
The body uses energy for essential processes such as breathing, keeping the heart beating and maintaining body temperature. It also uses energy for movement, including walking, working, playing sport and completing household tasks. A person who regularly uses more energy through movement may need to obtain more energy from their diet.
How physical activity changes energy needs
Physical activity level describes how much movement and exercise a person does. It can range from very low activity, such as sitting for much of the day, to high activity, such as training regularly or having a physically demanding job.
As activity increases, energy expenditure usually increases too. Energy expenditure means the energy used by the body. If a person does not replace this energy through food and drink, they may feel tired and find it more difficult to maintain their usual activities. A person with a lower activity level generally uses less energy through movement, so choosing large portions of high-energy foods regularly could contribute to an energy surplus.
An energy balance occurs when energy intake from food and drink is broadly equal to energy used by the body. An energy surplus occurs when intake is greater than expenditure over time, while an energy deficit occurs when expenditure is greater than intake over time. These ideas help explain why food choice should be considered alongside a person’s lifestyle, rather than treating one food as suitable for everyone.
What is BMR?
Basal metabolic rate, or BMR, is the energy the body needs when at rest to maintain essential functions. It is not the total amount of energy a person needs in a day because daily movement and other activities also use energy.
BMR differs between individuals. Body size, age, sex and growth can affect it. For example, a growing teenager needs energy and nutrients to support development, while two people of the same age may have different needs because their bodies and activity patterns are different. In an exam answer, avoid suggesting that activity level is the only influence on energy requirement.
How activity level can affect food choice
Physical activity level can influence several practical food choices:
- Portion size: a very active person may choose a larger portion to help meet increased energy needs, whereas a less active person may choose a smaller portion.
- Meal pattern: someone who trains or works actively may plan meals and snacks around their routine so that food is available when needed.
- Choice of carbohydrate foods: bread, rice, pasta, potatoes and cereals provide carbohydrate, which the body can use as an energy source. These foods may be included in meals for an active person, depending on the rest of their diet and individual needs.
- Nutrient density: nutrient-dense foods provide useful nutrients as well as energy. Examples include wholegrain foods, vegetables, fruit, pulses, dairy products or alternatives, eggs, fish, meat and other protein-rich foods.
- Convenience: a person with a busy training or work schedule may select portable foods or meals that are quick to prepare. Convenience still needs to be considered alongside nutritional value.
This does not mean that active people can eat unlimited amounts of any food. A suitable diet should still provide a range of nutrients, and food choices should reflect the individual’s overall needs.
Applying the factor to a practical example
Imagine comparing two people. Person A cycles to school, attends regular sports training and walks frequently. Person B spends most of the day sitting and does little planned exercise. Person A is likely to use more energy through movement, so their food choices may include larger portions or additional suitable snacks. Person B may need less energy from food because their activity level is lower.
A strong explanation would not simply say that Person A needs “more food”. It would link the activity to the reason: Person A has a high physical activity level, so they are likely to use more energy. They may choose a larger portion of a carbohydrate-based meal, such as pasta with vegetables and a protein-rich ingredient, to help meet their energy needs.
Remember that this is a comparison, not a medical prescription. The actual choice depends on factors such as age, body size, health, appetite, training routine and the rest of the person’s diet.
Linking activity to factors affecting choice
In AQA 3.5.1.1, physical activity level and energy needs are one factor affecting choice. In real life, factors overlap. A person may want a filling meal after exercise, but cost, available time, cooking skills, culture, allergies or personal preference may affect what they finally choose.
For example, a physically active pupil may choose a packed lunch containing a wholemeal sandwich, fruit and yoghurt because it is portable and provides energy and nutrients. Another pupil with the same activity level may choose different foods because of culture, taste, dietary requirements or what is available at home. The important point is to explain the relationship between activity, energy use and food choice without making assumptions about every individual.
Exam-ready summary
- Physical activity level means how much movement or exercise a person does.
- More physical activity usually increases energy expenditure and may increase energy needs.
- Energy balance compares energy from food and drink with energy used by the body.
- BMR is the energy needed at rest for essential body functions, not the whole daily requirement.
- Activity level can influence portion size, meal planning, snacks and carbohydrate choices.
- Food choice is also affected by age, growth, body size, health, culture, cost, time, skills and preference.
- Use a clear cause-and-effect explanation rather than claiming that one food is suitable for everyone.
Quick retrieval checklist
Can you define physical activity level, energy requirement, energy expenditure, energy balance and BMR? Can you explain why a highly active person may choose a larger portion? Can you give one example of how another factor affecting choice could change that decision?
This article follows the AQA GCSE Food Preparation and Nutrition specification, section 3.5.1.1, Food choice: Factors affecting choice. Check the current AQA specification for the wording and content required for your course, as official guidance can change.