1.6 Identify the amounts of energy supplied by 4g of each source

This guide will help you answer 1.6 Identify the amounts of energy supplied by 4g of each source.

Every food we eat gives us energy. The technical term for energy in food is kilocalories (kcal), sometimes just called calories. In the UK, we often use both kilocalories (kcal) and kilojoules (kJ). One kilocalorie is about 4.184 kilojoules. Nutritionists commonly look at three main energy sources: carbohydrates, protein, and fat. Alcohol provides energy too, but it is not considered a nutrient.

In this guide, you will find the specific amounts of energy supplied by 4 grams of carbohydrates, protein, fat, and alcohol. You will also see how this knowledge applies to food choices and overall health.

Carbohydrates

Carbohydrates are a main energy source for the body. They include sugars, starches, and fibre (mainly found in plants). The usable portion of carbohydrates gives a fixed amount of energy when digested and absorbed.

• 1 gram of carbohydrate provides 4 kilocalories (kcal)
• 4 grams of carbohydrate give 16 kilocalories (4 kcal x 4g = 16 kcal)

This amount is the same for both simple sugars and starches. Fibre is included as a carbohydrate but the body cannot fully digest it, so fibre provides little or no energy.

When you eat 4 grams of carbohydrate (like a spoonful of sugar or a bite of bread), your body receives 16 kcal of energy.

Protein

Protein is made from amino acids. It builds and repairs body tissues. Protein is also used for energy, though this is not its main role.

• 1 gram of protein supplies 4 kilocalories
• 4 grams of protein supply 16 kilocalories (4 kcal x 4g = 16 kcal)

Examples of foods high in protein are meat, fish, eggs, dairy products, pulses, and nuts. Eating 4 grams of protein (such as a small piece of chicken or cheese) gives you 16 kcal of energy.

Fat

Fat is the most energy-dense macronutrient. The body stores extra energy as fat for later use. Fat is found in animal and plant foods. Types include saturated, unsaturated, and trans fats.

• 1 gram of fat provides 9 kilocalories
• 4 grams of fat provide 36 kilocalories (9 kcal x 4g = 36 kcal)

This is more than double the amount supplied by the same quantity of carbohydrate or protein. Eating 4 grams of fat (about a teaspoon of oil or butter) gives you 36 kcal.

Alcohol

Alcohol is not a nutrient, but it does provide energy. The body cannot store alcohol and must process it immediately. Energy from alcohol cannot be used for body repair or growth.

• 1 gram of pure alcohol supplies 7 kilocalories
• 4 grams of pure alcohol supply 28 kilocalories (7 kcal x 4g = 28 kcal)

Alcohol is found in drinks such as beer, wine, and spirits. It contributes to energy intake and can encourage weight gain.

Energy Supplied by 4 Grams of Each Source

Source	Energy per gram (kcal)	Energy from 4g (kcal)
Carbohydrate	4	16
Protein	4	16
Fat	9	36
Alcohol	7	28

This table shows how much energy you get by eating 4 grams of each source.

Why the Energy Values Matter

Knowing these energy values is useful for several reasons. It helps you compare foods and make healthier choices. For example, you may want to reduce fat or alcohol intake because they give more energy in smaller amounts. This can help manage body weight and improve general health.

When planning meals, understanding these differences can guide you in picking foods that match your needs. If you need extra energy, foods high in fat may suit you. If you want to control your energy intake, higher-protein and lower-fat foods are better choices.

Sources of Each Macronutrient

You find carbohydrates in:

• Bread
• Rice
• Pasta
• Potatoes
• Sugar
• Fruits

Protein sources include:

• Meat
• Fish
• Milk
• Cheese
• Eggs
• Beans and lentils
• Soya products

Fat is found in:

• Oils and spreads
• Butter
• Cheese
• Meat
• Nuts and seeds
• Pastries and cakes

Alcohol is found in:

• Beer
• Wine
• Spirits
• Cider

Remember, most foods contain a mix of nutrients, but often one type is higher than the others.

How the Body Uses Each Source

Carbohydrate is the body’s preferred energy source for muscles and the brain. The body breaks it down into glucose for quick use. Surplus glucose is stored as glycogen in the liver and muscles, or as fat in body tissues.

Protein is mainly used to build and repair tissues, make enzymes and hormones, and support the immune system. The body does not like to use protein for energy unless there is not enough carbohydrate or fat available.

Fat is used for slow-release energy, cell structure, protection of organs, and to absorb certain vitamins. The body can store large amounts of fat, which provides a long-term energy reserve.

Alcohol is not needed by the body and can be harmful. The liver breaks down alcohol as a priority, often before other nutrients are processed. This can disrupt normal energy balance.

How to Calculate Energy from Food Labels

Almost all UK food labels list energy in kilocalories and kilojoules per 100 grams, and often per portion. You can use the per-gram energy values to check how much energy you are eating.

For example, if a snack bar contains 8 grams of fat, the energy from fat is:

• 8g x 9 kcal = 72 kcal from fat

If the same bar has 20 grams of carbohydrate:

• 20g x 4 kcal = 80 kcal from carbohydrate

Understanding this helps you decide if a food suits your nutritional needs or goals.

Portion Sizes and Energy Intake

The energy you get from food depends on amount eaten. Four grams is a useful comparison, but most people eat larger portions. For instance:

• A slice of bread (about 30g of carbohydrate) supplies 120 kcal from carbohydrate alone.
• A tablespoon of oil (about 14g of fat) supplies over 120 kcal from fat.

Weight management depends on balancing energy from food and drink with energy used by physical activity and daily life.

Balancing Macronutrients in the Diet

Both too much and too little energy can affect health. Consuming more energy than needed leads to weight gain. Taking in less than needed results in weight loss.

Recommended daily energy from each macronutrient is:

• Carbohydrates: roughly 50% of daily energy
• Protein: about 15% of daily energy
• Fat: no more than 35% of daily energy

These figures are guides. Needs change with age, activity, health, and other factors.

The Role of Alcohol in Diet

Alcohol adds energy to the diet but contains no useful nutrients. Regular drinking often leads to taking in extra energy, which can add to body fat.

4 grams of alcohol is found in about:

• 50ml of wine
• 100ml of beer
• 15ml of spirits

This shows how easy it is to add extra energy by drinking alcohol.

Health Effects of Too Little or Too Much Energy

Taking in more energy than needed leads to storing extra as fat. Over time, this can result in overweight or obesity, raising the risk of heart disease, diabetes, and other conditions.

Getting too little energy can cause tiredness, poor immune function, and slow growth or repair. Both too much and too little energy can harm wellbeing.

Having a good balance of carbohydrate, protein, and fat supports overall health. Variety in food choices is key.

Energy from 4g of Each Source

Use this table to remember the key values:

Source	4g Energy (kcal)
Carbohydrate	16
Protein	16
Fat	36
Alcohol	28

Points to Remember

• Carbohydrates and protein both give 4 kcal per gram.
• Fat gives 9 kcal per gram, so it is the richest energy source.
• Alcohol gives 7 kcal per gram, higher than carbs and protein, less than fat.
• 4 grams of each provide different amounts of energy: fat gives the most.

This knowledge is useful for meal planning, reading food labels, and achieving a healthy diet.

Final Thoughts

Knowing how much energy comes from 4 grams of carbohydrate, protein, fat, and alcohol is a building block for good nutrition. This skill helps you judge what is in the foods and drinks you choose every day. Reading labels and making comparisons start with understanding these numbers.

Choosing a healthy balance is shaped by these basic facts. Too much fat or alcohol in the diet can push up energy intake, raising health risks over time. Relying on carbohydrate and protein, with enough healthy fats, offers a steady source of energy and supports growth, recovery, and everyday tasks.

Awareness can help you make small changes that support better health. Swapping a high-fat spread for a leaner one, or reducing alcoholic drinks, could lower your energy intake without affecting your enjoyment of food. Using tables or label information puts you in charge of your choices.

Applying your new skills will improve your ability to support others with nutrition too. By learning the simple maths behind food energy, you can help friends, family, or those you support make better decisions. Start by checking labels, comparing foods, and discussing what a balanced intake looks like. Every small change counts in promoting wellbeing.