Energy balance and Dietary Reference Values: the energy value of nutrients, basal metabolic rate and physical activity level, total energy requirements, the consequences of energy imbalance, and the meaning and use of DRVs, RNI, EAR and the Eatwell Guide.

What this dot point is asking

CCEA wants you to explain how food energy is measured and the energy value of each nutrient, define basal metabolic rate and physical activity level and explain what determines total energy needs, describe the consequences of energy imbalance, and explain the Dietary Reference Values (DRVs) including EAR, RNI and the use of the Eatwell Guide.

Energy value and energy balance

Food energy is measured in kilojoules (kJ) and kilocalories (kcal), where 1 kcal is about 4.2 kJ. The energy values of the nutrients are: fat about 37 kJ (9 kcal) per gram, carbohydrate about 16 kJ (3.75 kcal), protein about 17 kJ (4 kcal) and alcohol about 29 kJ (7 kcal) per gram. Fat is therefore the most energy-dense, which is why high-fat diets readily cause an energy surplus.

Dietary Reference Values

The Eatwell Guide turns these values into practical advice by showing the proportions of the main food groups for a balanced diet: plenty of fruit and vegetables and starchy carbohydrates, some protein and dairy or alternatives, and only small amounts of foods high in fat, salt and sugar. CCEA expects you to use both the DRV terms and the Eatwell Guide when judging the adequacy of a diet.

Examples in context

Example 1. Why energy needs change with age. A growing teenager has a high BMR and high activity, so a large energy intake is appropriate. The same person at 60, with less muscle and a quieter lifestyle, needs noticeably less. Eating the teenage amount in later life would create a surplus and weight gain, which links energy balance to the life-stage requirements examined in the module.

Example 2. Using the Eatwell Guide to balance a diet. A diet heavy in fried and sugary foods supplies excess energy with poor nutrient density. Rebuilding meals around the Eatwell Guide proportions, with more vegetables and wholegrain starch and only small amounts of high-fat, high-sugar foods, brings energy intake closer to the EAR while improving overall nutrition. This shows DRVs and the Eatwell Guide working together.

Try this

Q1. State the energy value, in kJ per gram, of fat, carbohydrate and protein. [3 marks]

• Cue. Fat about 37 kJ, carbohydrate about 16 kJ, protein about 17 kJ per gram.

Q2. Explain what is meant by basal metabolic rate. [2 marks]

• Cue. The energy needed at complete rest to keep the body alive (breathing, heartbeat, temperature, organ function).

Q3. State which Dietary Reference Value is used for energy and why. [2 marks]

• Cue. The Estimated Average Requirement (EAR), because using the group average avoids encouraging overconsumption.