What foods have the most kilojoules?

One gram of fat contains more than double the energy of one gram of carbohydrate or protein, making fatty foods the most energy-dense options available. This principle explains why certain foods have the most kilojoules, offering significant energy in smaller portions.

Quick Summary

Fats, oils, nuts, seeds, and processed sweets are among the foods highest in kilojoules. The article explores why certain macronutrients are more energy-dense and provides examples of both healthy and unhealthy high-kilojoule options, detailing their nutritional impact.

Key Points

• Fats are the most kilojoule-dense macronutrient: Providing 37 kJ per gram, fats contain more than twice the energy of carbohydrates and proteins.

• High-kilojoule foods include fats, oils, nuts, and seeds: These items are packed with concentrated energy, making them excellent for boosting intake in small portions.

• Nutrient density matters: Prioritize high-kilojoule foods like avocados, nuts, and oily fish that offer health benefits over processed, kilojoule-dense snacks.

• Understand kilojoules vs. calories: Kilojoules are the metric unit for energy, while calories are another common unit, with 1 calorie being equivalent to approximately 4.2 kilojoules.

• High-kilojoule intake is key for healthy weight gain: Individuals seeking to increase body mass should strategically incorporate healthy, high-kilojoule foods into their diets.

• Processed foods often have high, empty kilojoules: These items are high in unhealthy fats and added sugars, offering significant energy without substantial nutritional value.

• Choosing the right fats is crucial: Replace sources of saturated and trans fats with healthier monounsaturated and polyunsaturated fats to benefit cardiovascular health.

The Science of Kilojoules: Why Fat is King

The energy content of food is determined by its macronutrient composition: carbohydrates, proteins, and fats. A kilojoule (kJ) is the metric unit for energy, equivalent to about 0.239 calories. Understanding the energy density of each macronutrient is key to answering what foods have the most kilojoules. Fat is the most energy-dense, providing 37 kilojoules per gram, compared to the 17 kilojoules per gram found in both protein and carbohydrates. This high energy concentration means that even small amounts of high-fat foods can contribute significantly to your daily energy intake. Alcohol also contains a high energy value of 29 kJ per gram but is not considered a nutrient.

The Highest Kilojoule Food Groups

Based on their high fat and sugar content, certain food groups consistently top the list for kilojoule density. These can be sorted into both nutrient-dense and nutrient-poor categories, depending on their overall nutritional profile.

• Oils and Butters: As pure fat sources, cooking oils like olive oil, coconut oil, and canola oil are the most energy-dense foods, providing approximately 37 kJ per gram. Butter and other animal fats are also extremely high in kilojoules.
• Nuts and Seeds: Rich in healthy fats and protein, nuts (like macadamias, almonds, and walnuts) and seeds (chia, flax, and pumpkin) are excellent sources of concentrated energy. A handful provides a significant kilojoule boost.
• Nut Butters: Spreads like peanut and almond butter are high in kilojoules due to their fat and protein content, making them a dense energy source often used for healthy weight gain.
• Dairy Products: Full-fat cheeses, creams, and some yogurts are high in both saturated fats and kilojoules. These items are a compact source of energy and calcium.
• Dried Fruits: The removal of water concentrates the natural sugars, making dried fruits like dates and prunes a much more kilojoule-dense option than their fresh counterparts.
• Fatty Fish: Oily fish like salmon, mackerel, and sardines are high in kilojoules due to their omega-3 fatty acid content, which is beneficial for health.
• Red and Fatty Meats: Fatty cuts of beef, pork, and lamb contain higher kilojoules compared to lean meats due to their saturated fat content.
• Processed and Fried Foods: These items, including chips, cookies, cakes, and fried chicken, are often high in added sugars, unhealthy fats, and kilojoules with little nutritional value.

List of High-Kilojoule Foods

• Oils (Olive, Coconut): A single tablespoon can add over 500 kJ to a meal.
• Macadamia Nuts: These are among the most kilojoule-dense nuts, packing a powerful energy punch in a small serving.
• Peanut Butter: A spreadable source of healthy fats and protein, ideal for boosting energy.
• Dark Chocolate (70%+): High in cocoa butter (a fat), dark chocolate offers concentrated kilojoules and antioxidants.
• Avocados: This fruit is rich in heart-healthy monounsaturated fats and is significantly more energy-dense than other fruits.
• Full-Fat Cheese: Cheddar, gouda, and other hard cheeses are very high in kilojoules and saturated fat.
• Dried Prunes (Plums): Offers concentrated sugar and fibre for a quick energy boost.
• Salmon: An excellent source of protein and omega-3 fatty acids, making it a high-quality, kilojoule-rich food.
• Sweet Potatoes: A great source of complex carbohydrates that provide sustained energy.
• Red Meat (e.g., Lamb): Higher fat cuts are packed with kilojoules, protein, and iron.

Comparison of Energy-Dense Foods

Food Item (per 100g)	Primary Macronutrient(s)	Energy (Approx. kJ)	Nutritional Context
Butter	Fat	3113	Very high in saturated fat and kilojoules.
Cheddar Cheese	Fat, Protein	1740	Good source of calcium, but high in saturated fat and sodium.
Macadamia Nuts	Fat, Protein	2800	Excellent source of healthy fats, but very high kilojoule content.
Avocado	Fat	670	Nutrient-dense, offering healthy fats, fiber, and vitamins.
Dried Dates	Carbohydrates	1178	A source of quick-release sugars, fiber, and minerals.
Salmon	Protein, Fat	815	Rich in protein and beneficial omega-3 fatty acids.
Wholemeal Bread	Carbohydrates, Fiber	910	A better option than white bread for sustained energy due to fiber.
Potato Chips	Fat, Carbohydrates	2240	High kilojoule, but low nutrient value and high in sodium.

Conclusion

Ultimately, the foods with the most kilojoules are those with the highest fat content. While fats provide the most energy per gram, it is crucial to distinguish between healthy, nutrient-dense options like nuts, seeds, avocados, and oily fish, and nutrient-poor choices like processed snacks and sweets. For individuals aiming for healthy weight gain, incorporating wholesome, high-kilojoule foods is a strategic approach. For those managing their weight, understanding the energy density of different food types is key to making informed dietary decisions. A balanced diet should include a variety of macronutrients, with a focus on nutrient-rich sources for overall health and well-being.

The Importance of Macronutrient Balance

Balancing your intake of carbohydrates, proteins, and fats is fundamental for a healthy diet. While high-kilojoule foods can provide concentrated energy, relying too heavily on low-quality options can lead to nutrient deficiencies and health issues. Healthy sources of fats, carbohydrates, and proteins offer more than just energy; they also provide essential vitamins, minerals, and fiber, contributing to overall well-being. A diet rich in whole foods helps ensure you get a broad spectrum of nutrients alongside your energy needs. Combining nutrient-dense, high-kilojoule foods (like nuts or seeds) with lower-kilojoule items (like vegetables) can help achieve a balanced intake.

Making Informed Choices

To manage your kilojoule intake effectively, reading food labels is essential. Pay attention to both the total kilojoules and the macronutrient breakdown. For instance, a small serving of a high-fat food may have the same number of kilojoules as a larger serving of a low-fat food. Understanding this difference helps in portion control. For a boost of energy, grabbing a handful of nuts is a far more nutritious choice than reaching for a bag of chips, even if both are high in kilojoules. The focus should be on getting the best nutritional value for your energy intake. For further authoritative information on this topic, consult the Better Health Channel's guide on energy in food.

Not All Kilojoules Are Created Equal

The source of your kilojoules is just as important as the quantity. Kilojoules from wholesome, unprocessed foods tend to provide sustained energy, keeping you feeling fuller for longer. In contrast, kilojoules from refined sugars and processed foods can cause rapid spikes and crashes in blood sugar, leading to fatigue and cravings. A focus on whole grains, lean proteins, healthy fats, and fruits and vegetables ensures that the energy you consume is high-quality and beneficial for your body.

The Role of Dietary Fat

Despite their high kilojoule content, dietary fats are essential for many bodily functions, including hormone production and the absorption of fat-soluble vitamins (A, D, E, K). The key is choosing healthier fats, such as monounsaturated and polyunsaturated fats found in olive oil, nuts, seeds, and avocados, over saturated and trans fats prevalent in many processed foods and animal products. Opting for the right types of fats ensures you get necessary nutrients along with the energy.

Frequently Asked Questions

What is the most energy-dense food in terms of kilojoules?

Pure fats and oils, such as olive oil and butter, are the most energy-dense foods, as they contain the highest concentration of kilojoules per gram compared to all other food types.

Are all high-kilojoule foods unhealthy?

No, not all high-kilojoule foods are unhealthy. Nutrient-dense options like nuts, seeds, avocados, and oily fish provide healthy fats, protein, and essential micronutrients alongside their high energy content.

How can I add healthy, high-kilojoule foods to my diet?

You can add healthy high-kilojoule foods by snacking on nuts and seeds, adding nut butters to toast or smoothies, incorporating avocado into meals, and cooking with healthy oils like olive or coconut oil.

Why do nuts have so many kilojoules?

Nuts are very high in kilojoules because they are rich in healthy fats, which are the most energy-dense macronutrient. They also contain protein and fiber, making them a nutritious energy source.

Is it important to monitor kilojoule intake for weight management?

Yes, monitoring kilojoule intake is important for weight management. Consuming more kilojoules than your body burns can lead to weight gain, while a deficit can lead to weight loss.

What's the difference between kilojoules and calories?

Kilojoules and calories are both units of energy. One calorie is equal to approximately 4.2 kilojoules. Both units measure the energy content of food, but kilojoules are the metric standard.

What processed foods are highest in kilojoules?

Many processed foods are high in kilojoules due to high levels of added sugars and unhealthy fats. Examples include fried foods, sugary drinks, cakes, cookies, and chips.