Expert Nutrition

Energy Density – The Key to Weight Loss Success.

Reducing the energy density of your diet is one of the easiest and most effective ways of reducing your total calorie intake and arguable this is the most important thing to consider when changing your diet to lose weight.

Energy Density can be defined as the amount of energy (calories) that a food contains per gram. As discussed on the last page (energy content of food), fats and oils are the most calorie dense food group and therefore if you are trying to lose weight it makes sense to try and reduce the amount of fat and oils consumed in your diet. On the other hand water and fibre are the least energy dense nutrients and therefore foods that contain both water and fibre are smart options which can assist weight loss.

Weight Loss Tip: Eat less FAT, Eat more FIBRE!

Understanding the concept of energy density is extremely important for those trying to lose weight, so let’s start off with a practical example. On numerous occasions we have had clients tell us that potatoes are very fattening, well, are they?

Let’s compare 3 foods (all of which contain potato). Which of the following foods do you think contains the most energy (calories)?

  • 4 boiled potatoes (400g)
  • ½ cup of large cut chips (100g)
  • Packet of potato crisps (50g)

The answer, it’s actually a bit of trick question, they all have the same amount of energy (approximately 260 Calories), so what’s the difference? Energy density - lets explain.

Option 1: 4 boiled potatoes (Energy =~ 260 Cals / 0g of fat)
I’m sure most people would agree that eating 4 potatoes is very filling, for some people it would be a meal in itself. In fact, a well known study published by Halt and Colleagues (1995) showed that potatoes have a high degree of satiety, which basically refers to the feeling of fullness. Not only are high satiety foods more filling, but they also tend to reduce the likelihood of over-indulging at the next meal.

What are the main nutrients in potatoes? Carbohydrate - the body’s most ideal source of fuel, vitamins, minerals, water and there is also some fibre (even more if you leave the skin on). Win-win

Option 2: ½ cup large cup chips (energy ~260 Cals / 12g of fat)
Half a cup of large cut chips, be honest, when was the last time you ate ½ a cup of chips! Although this meal is 4 times smaller, the energy content is the same. As discussed previously fats and oils are the most energy dense nutrient and given that cooked chips are deep fried in oil naturally they will contain more calories. In summary as the fat or oil content of a meal increases so does the energy density.

Option 3: 50g packet of potato crisps (energy ~260 Cals / 15g of fat)
The energy content of the 50g packet of crisps is the same as the 4 small potatoes. In theory you could make 8 packets of crisps out of those 4 potatoes, but because of the fat content, the energy density of the packet of crisps is significantly greater. What makes the energy density of the packet crisps so high? As discussed in option 2 as the fat content increases so does the energy density. Most packet of crisps are normally made up of at least 30% fat. Additionally because the water content has been removed from the crisps this now concentrates the amount of energy per gram.

The next question you need to ask yourself is - will that packet of potato crisps satisfy your hunger? No, it’s just a tease! Most people soon go back to the vending machine for more. Unfortunately a packet of crisps contains a lot of energy (high energy density) without satisfying your hunger. Eating these kinds of foods can significantly impact on the total amount of energy consumed throughout the day (energy input) and make it difficult to lose weight.

It is important to understand that quite often your eyes are bigger than your stomach, just because a food isn’t satisfying your hunger, that does mean it’s not giving you more than enough energy. Therefore, if you’re trying to lose weight the trick is to find healthy foods that not only satisfy your hunger, but also are not too high in calories.

Don’t get us wrong, this is not to suggest that potatoes are a good weight loss food as potatoes do contain more calories than most other fruits and vegetables. However, this example does help to highlight a valuable point. We have had numerous clients who were quick to remove potatoes from their diet, but want they have failed to realise is that the deep fried and snack foods they were eating instead are a hell of a lot worse!

Case Study 1:

A woman contacted us for some advice regarding her weight loss plan. She knew that she had to reduce the total amount of calories she was consuming and therefore decided to skip breakfast. After not seeing any results, she also decided to start cutting back on her lunch as well, some days skipping lunch altogether. As you can imagine this woman was constantly hungry and to counter this she would snack a few times throughout her day to satisfy her hunger. We were contacted for advice after her weight started to increase, despite neglecting herself of 1-2 meals a day.

After analysing this woman’s new diet it was indentified that although she was eating less food throughout the day, the total amount of calories that she was consuming actually increased which lead to her weight gain. Although she was eating fewer meals, the snack foods that she added were very energy dense (eg chocolate, crisps, biscuits etc.) and lead to an overall net gain in daily calorie consumption.

Take home message, although some snack foods are not very filling they can actually contain more calories than a proper meal. It would be wise to limit the consumption of such foods.

Case Study 2:

A Chinese women approached our panel of experts for advice regarding her weight gain. This woman was exercising for about 3 hours a day and her average diet consisted of a piece of fruit for breakfast, a tuna salad for lunch and a stir-fry for dinner.

3 hours of exercise is a lot and you would normally expect the weight to be falling off you, so there was obviously something wrong with her diet. Now although a stir-fry can be a healthy meal, particularly if it is full of vegetables, an easy way to make it unhealthy is to deep fry everything that goes into it, before adding more oil and frying it again for a second time. It turns out that that this woman was going through about 1/2 litre of oil a night, just to cook her stir-fry. That’s a lot of oil!

When we highlighted the fact that it was probably the excessive amount of oil that was causing her weight gain, her response was “No, it’s ok, I’m using olive oil, and it’s healthy for you!?”

Yes, some studies suggest that olive oil may convey some health benefits, however the key is still moderation. Regardless of whether the oil comes in the form of olive, canola, peanut, or in its solid form of fat, the energy density of fats and oils remains the same (9 Cals/g). Remember if we are trying to lose weight we should look to reduce the amount of energy consumed. So although olive oil may offer some health benefits, it also provides a lot of energy and for the person trying to lose weight it should be used sparingly.

What kind of foods are low in energy density?

The easiest way to answer this question is to look for foods that are low in fat whilst also being high in fibre and water content. Good examples include most foods that come from a plant and in particular fruits and vegetables. Vegetables (with the exception of potatoes) are among the lowest energy dense foods and therefore you can eat as many vegetables as you like. They will provide you with lots of healthy nutrients, help to satisfy your hunger and because they are low in energy density they will help you to lose weight.

Weight Loss Tip: Make vegetables or fruit the main part of every meal.

While we’re talking about fruit and vegetables the daily recommendation is that we eat a minimum of 5 serves of vegetables and at least 2 serves of fruit every day. Meeting these guidelines is a great way to improve your diet and will help you to achieve a healthy body weight.

Let’s look at another snack food example. A large apple and a chocolate biscuit have about the same energy content (approx 100 Cals), so what’s the difference? Energy density.

How many large apples could you eat in one sitting? How many chocolate biscuits could you eat in one sitting? See how the apples provide you with a little bit of energy but also satisfies your hunger. The chocolate biscuit on the other hand pretty much only provides you with the calories. Because the biscuits don’t satisfy your hunger and taste good it’s easy to eat more biscuits (and calories) than you need.

Incidentally the foods you snack on throughout the day should be not be greater than 100 calories in total per snack and you should limit yourself to just 2 snacks a day. This makes an apple an ideal snack for someone who is trying to maintain or lose weight. Remember an apple a day keeps the doctor away!

healthy snack choice

I hope buy now that you are starting to see a little bit of a trend with all this talk about calories. The key to successful weight loss is to find foods that are low in calories, high in nutrition (vitamins, minerals etc.) that satisfy your hunger.

What foods should I avoid if I’m trying to lose weight?

We personally don’t like using the word “avoid” as we shouldn’t neglect ourselves altogether, but it is advised that you should definitely limit the consumption of certain foods. Naturally anything that is high in fat, which includes things like butter, cooking oil, margarine spreads, but also includes snack foods like chips, chocolate and cheese. This is not to say that you cut out all fats and oils, but definitely look to cut back.

Other foods that are high in energy density include most baked goods. This basically means anything you would normally buy from the bakery with the exception of bread. Examples include cakes, tarts, pastries, pies, sausage rolls etc. Baked goods are full of hidden fat. Why? Because fat, in particular saturated fat (the nasty stuff) is very sticky and therefore makes a great binding agent (helps the ingredients stick together) when cooking.

Note: Although some people would argue that bread is fatting, it’s not so much the bread you have to worry about, it’s what you put on it. Aim for a bread that is either wholemeal or multigrain, the more it looks like it comes from a plant the better.

Another common misconception is that pasta is fattening, this simply is not true. Pasta is a good, healthy food, particularly if it is wholegrain. What can make pasta unhealthy is when you cover it in a creamy sauce. Creamy sauces are yet another good example of a high energy dense food. You’d be surprised how much fat you’ll find in a creamy sauce. If you do like pasta, a good idea is to replace creamy sauces (or melted cheese) with tomato based sauces. A tomato based sauce with herbs and spices, and a few extra vegetables helps to turn pasta from a good meal into a great healthy meal.

Next you should also look to cut down on foods high in refined sugars, which generally includes everything that comes with a cartoon character on the packet and/or those that give you a toy. As a general rule the more processed a food becomes, the less healthy it is. A good example of how processing food can significantly impact on the health value of a particular food is bottled fruit juice. While fruit in its natural form is one of the healthiest foods you could possible eat, some fruit juices are not. Fruit juice is very concentrated and normally contains added sugar. Although fruit juice may provide some nutritional value in the form of vitamins, it also contains a lot of energy, so for those trying to lose weight, water is a much better option. If you do like to drink fruit juice we recommend that you squeeze it yourself and don’t let the pulpy stuff go to waste, eat that as well.

What about high calorie drinks?

Fluids drunk throughout your day can also significantly impact on the total amount of calories consumed (~20% of total energy intake) and therefore switching to low energy dense drinks make sense. Try to avoid or cut back on soft drinks (diet soft drinks are ok) chocolate milks, alcohol (aim for moderation) , bottled fruit juices, sports and energy drinks.

Smart alternative options include water, tea (particularly green tea), coffee and low fat milk. If you enjoy a tea or coffee that’s fine, these drinks themselves don’t contain hardly any calories, you just need to be careful of what you add to it (ie sugar and cream) and more importantly be mindful of what you are eating with it (ie biscuits, cakes etc.)

How to work out the energy density of a food?

By law, each packaged food item must contain a nutritional information panel, which summaries the energy content of the food. Now although we said at the start that we wouldn’t have you counting calories, don’t worry we won’t, but what you can do is look at the nutritional information panel to see how much energy a food contains.

When looking to buy your foods, we suggest you ignore all of the healthy ticks and slogans on the front of the packet (marketing hype) and turn straight to the back, where you can review the nutritional information panel.

In years gone by dieticians would always recommend that you look for food items that are less than 10g fat / per 100g (ie less than 10% fat) and although this is still a smart recommendation, some food companies have caught on and are starting to reduced the fat content, but unfortunately are replacing it with a high sugar content. Although fat is a lot more energy dense then sugar, adding refined sugars to a food, does however still increase the total energy content, which can be detrimental to your weight loss plans. Therefore the easiest way to identify the energy density of a food is not so much to focus on the fat content but instead the total energy content.

If you look at the top line of the nutritional information panel you will see the word “Energy”. You will also notice 2 columns “per serve” and “per 100g”. If you refer to the per 100g you will be able to compare different food items as well as work out the energy density.

Nutritional Information Panel

Basically the higher the energy content per 100g, the higher the energy density of the food. Therefore if our goal is to reduce energy input, we should look for food items that have a lower energy density (ie less energy per 100 grams). This means that although you may be eating the same volume of food you will be consuming fewer calories.

For example when comparing dairy products you will find that low fat or skim milk has a lower energy density (ie less energy per 100ml) than the full cream milk and therefore for those trying to lose weight, the low fat or skim would be a smarter option (not recommended for children under the age of 2). If you would prefer to stay with the full cream which has a higher energy content, you should aim to reduce the amount you use (portion size).

Another benefit to this technique is that it allows you to compare different foods. For example both cheese and low fat yogurt are dairy products, however cheeses can easily get above 500cals (2100kj) per 100g making them very energy dense, whereas low fat yogurt normally comes in under 100cals (420kj) per 100g making the low fat yogurt a smarter weight loss option.

Foods that are less than 100Cals (~420kj) per 100g are generally considered low in energy density and so you can normally happily consume these foods without having to worry about your waistline. Foods that get above 300Cals (1200kj) per 100g are considered high in energy density so look to limit the consumption of these foods when trying to lose weight. We've put together some simple guidelines below.

Energy Density Guidelines for Food

Less than 100 Cal (420kj) /100g Eat freely
100Cal (420kj) – 300Cal (1260kj) /100g Eat in moderation
Greater than 300 Cal (1260kj) /100g Eat sparingly

Energy Density Guidelines for Fluids

Less than 10 Cal (~40kj) /100ml Drink freely
10 Cal (~40kj)– 40 Cal (160kj) /100ml Drink in moderation
Greater than 40 Cal (160kj) /100ml Drink sparingly

Important note: The above guidelines should only be used for determining the energy content of food and not the overall nutritional value.

Weight Loss Homework

  • Find foods that you enjoy, that also fall into the low energy density range. Your goals is to try and incorporate more of these into your diet.
  • Identify foods that you currently eat that fall into the high energy density range and look to replace these with a low energy density alternatives
  • Start your main meals with a water-based soup, or salad. Throw in lots of vegetables, this will provide you with lots of healthy nutrients as well as help to satisfy your hunger. Your main meal should include whole grains, include a few more vegetables and finish with a small portion of lean protein.
  • Increase the ratio of plant based foods mainly fruits and vegetables. In particular aim to make vegetables the main part of lunch and dinner and include fruit as part of your breakfast. Additionally fruit should be used to replace other snack foods throughout the day. Remember at least 5 serves of veges and at least 2 serves of fruit everyday.
  • Look for breakfast cereals that are high in fibre and look like they come from a plant. I don’t think you’ll find too many fruits in fruit loops!

A study published in the American Journal of Clinical Nutrition (Rolls et al. 2006) suggests that by reducing the energy density of your diet by 25% you can significantly reduce the amount of energy consumed throughout your day without increasing hunger. Therefore when it comes to losing weight it makes sense to replace high energy dense foods with low energy dense foods. In doing so, you can actually eat more food while consuming less energy.

In summary by reducing the fat content of our diet we can significantly reduce the energy density and the overall energy input throughout the day. Additionally by eating more fibre this will not only help to keep our bowels healthy but will also help to keep us full. Overall by reducing the energy density of our diet we can significantly reduce the total amount calories consumed throughout the day and also satisfy our hunger. This concept is one of the most important ingredients to achieving successful weight loss.

Given the amount of information discussed on this page we recommend you either read it again and take notes or print this page out. Good luck!

On the next page we are going to turn our attention towards portion size and why eating more can be a healthy option.

Healthy options to consider.
Snack foods and take away meals can make up some of the most energy dense foods so we review some healthy options. (Note - these pages will open in a new window. To return here simply close them down such that you can move to the next stage of this chapter.)

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