Calorie density 101: What it is and how it impacts weight loss

You’ve almost definitely heard of calorie counting, but what about calorie density? The 2 might seem similar — they both have the word ‘calorie’ in their name, after all — but they’re actually quite different.

While calorie counting only looks at the number of calories in a particular food, calorie density gives a much more in-depth assessment. Instead, it tells us about how much energy a food provides relative to its weight.

This all might sound a little confusing, but once you unpack the concept of calorie density, it becomes pretty straightforward. Here’s what you should know about calorie density and how it can help you lose weight.

What is calorie density?

Put simply, calorie density is the number of calories within a particular food in relation to its weight or volume. You’ll likely see a food’s calorie density measured as calories per 100g (or 3.5 oz if you’re looking at an imperial measurement). You might also see it referred to as energy density.

Different foods have different calorie densities. For example, tomatoes have about 18 calories per 100g, wholemeal pasta has 149 calories per 100g, and olive oil has around 884 calories per 100g. This makes tomatoes the least calorie-dense food out of the 3 and olive oil the most calorie-dense. 

The reason is that foods with high water content (such as tomatoes) typically have a lower calorie density, while fat (which olive oil contains a lot of) is the most calorie-dense macronutrient. It has about 9 calories per gram (900 calories per 100g) whereas carbs and protein both contain 4 calories per gram (400 calories per 100g) [1].

How do you calculate calorie density?

If you’re buying a bag of rice or a carton of milk, it’s easy to work out its calorie density. You’ll see it in the nutrition panel, usually given per serve and per 100g.

But if you’re eating something that doesn’t come out of a packet, like fresh fruit and veg, you might have a little more trouble uncovering its nutritional information. Instead, you can calculate its calorie density by dividing the number of calories per serving by the serving size.

Let’s use grapes as an example. One cup of grapes is generally considered one serving. In grams, that’s about 150g. A single serving of grapes has about 104 calories. If we divide 104 by 150, we can work out that the energy density per gram is 0.69 calories and the energy density per 100g is 69 calories (0.69 x 100).

Compare this to tomatoes, which contain 18 calories per 100g and wholemeal pasta, which has about 149 calories per 100g, and we can see that grapes sit somewhere in between.

What role does calorie density play in weight loss?

So, what’s the advantage of understanding calorie density? Well, if you know the difference between the energy density of different foods, you can opt for things that are high in nutrition but lower in calories — potentially helping you to lose weight.

We know that eating too many high-calorie, low-nutrition foods can lead to weight gain. That’s simply because they give your body a lot of energy in small portion sizes, meaning they don’t really fill you up. Plus, research shows they’re quite easy to overeat.

On the other hand, low calorie density foods can make you feel fuller because you’re able to eat bigger portions without consuming as many calories. 

This is why calorie density is preferable to simply calorie counting. If you’re counting calories, you might hit your daily calorie limit by only eating a few pizza slices and a block of chocolate — and still end up hungry. But if you eat a bowl of porridge, a salad sandwich on wholemeal bread, and a plate of roast chicken with veggies, you might very well consume a similar number of calories but feel much more satisfied.

The other advantage is that many low calorie density foods tend to be more nutritious. Healthier foods like vegetables, fruits, whole grains, and legumes are on the lower end when it comes to calorie density, while oils, meats, cheese, sweets, and processed foods are on the higher end.

Lower calorie-density foods are also higher in fibre, which takes longer to digest and keeps you fuller for longer — meaning you’re more inclined to eat less [2].

There have been several studies done on the relationship between calorie density and weight, too.  Research shows that eating a high-energy-density diet is closely linked to obesity and a higher waist circumference, as well as related conditions like insulin resistance and metabolic disorders [3]. By contrast, lower energy density diets are connected to lower amounts of abdominal fat [4].

The difference between calorie density and nutrient density

You may also have heard of a concept known as ‘nutrient density’ in relation to food. 

Rather than being a measure of how many calories are in a specific weight of food, nutrient density refers to the amount of nutrients a food provides relative to its calorie content. Foods with a high nutrient density are usually referred to as being nutrient-dense. This means they pack a real nutritional punch for the number of calories they contain [5].

Many low calorie density foods — such as vegetables, fruit, and whole grains — also happen to be nutrient-dense foods because they offer vitamins, minerals, complex carbs, and other things that are good for your body [6].

Examples of low calorie density foods

The good news is that there are lots of low calorie dense foods to choose from that are also high in nutritional value. Some of our favourites include:

• Vegetables like spinach, broccoli, cucumber, zucchini, carrots, and potatoes
• Fruits such as apples, pears, oranges, berries, grapes, watermelon, and bananas (aim for fresh or frozen fruit, as dried fruits and juices are higher in calorie density)
• Whole grains including oats, brown rice, and wholemeal bread and pasta
• Legumes like beans, lentils, and chickpeas
• Lean meats and poultry, and fish

How to approach weight loss sustainably

Measuring a food’s calorie density is just one piece of a much bigger puzzle. Losing weight healthily and sustainably takes a multipronged strategy that combines diet, exercise, a few lifestyle tweaks and, sometimes, a helping hand along the way.

If you want to lose weight and keep it off, here’s how you can do so.

Don’t just go for low-cal foods

Even though foods like nuts, oils, and full-fat dairy are higher in energy density, that’s not to say you can’t include them in your diet. There are actually several examples of high calorie density foods that are also good for you, such as avocado, raw nuts, and olive oil. 

It’s all about monitoring your intake and ensuring much of your diet is made up of low calorie density but highly nutritious foods — like fresh fruit and veg, whole grains, and legumes. Higher energy density but still healthy foods like the ones we mentioned earlier can be incorporated into your diet in smaller amounts.

Incorporate more exercise into your day

Exercise is hugely important. It curbs your risk of certain diseases (like stroke and type 2 diabetes), strengthens your muscles and bones, supports brain health, gives you more energy, helps you sleep better, and improves your mood [7][8].

It can also help you lose or manage your weight. This is because exercise burns calories, and the more intense the exercise, the more calories you burn.

Moderate to high-intensity exercise like swimming, jogging or cycling is considered the most effective for weight loss [9]. But if you’re new to exercising, you don’t have to kick things off with a 45-minute run. Instead, start with a 30-minute walk on most days of the week and steadily build up to more intense forms of exercise as your fitness improves.

Drink plenty of water

Did you know drinking adequate amounts of water can support your weight loss goals?

Research suggests that water provides lots of benefits when it comes to losing weight, like stimulating your metabolism, supporting your body’s ability to burn fat, making workouts easier by keeping your body hydrated, and suppressing your appetite. Opting for water instead of high energy density drinks like fruit juice or soft drinks can also help you consume fewer calories overall [10].

For weight loss, you want to aim for about 1-2 litres every day.

Tweak your habits

There may be other habits hampering your ability to lose weight. Things like drinking too much booze, stress, sleeping badly, and smoking can all promote weight gain.

Aim to take control of your stress levels, look at your sleep habits to see where you can make improvements and encourage better sleep, quit smoking, and try to drink just a moderate amount of alcohol every week. 

If we look at alcoholic drinks in terms of energy density, we find that most are very calorie-dense. This is largely because alcohol itself contains around 7 calories per gram (or 700 calories per 100g) — making it higher in energy density than both carbs and protein and second only to fat, which we know has 9 calories per gram (or 900 calories per 100g) [1].

Try a weight loss program

If you want to take a holistic approach to weight loss, try a weight loss program like Juniper’s Weight Reset Programme.

The program encompasses medication to suppress your appetite and bolster your metabolism, health tracking so you can check in on your goals, access to a private weight loss community and educational videos and articles, and ongoing, individual support from dietitians and health coaches. 

Juniper’s expert health coaches can help you understand and analyse the foods you’re putting into your body, assessing their calorie density, nutrient density, and their role in your weight loss journey — allowing you to feel empowered about your dietary choices. 

As well, they’ll look at things like stress, sleep, and exercise, giving you the advice you need to set sustainable healthy habits and lose weight for good.

Photo credit: Farhad Ibrahimzade / Unsplash