The simplest diets focus on calories. They offer ways to work out how many calories a person needs, provide methods for calculating the calorie content of food eaten, and act as guides to help people increase or decrease calorie consumption according to their chosen goals.
Some diets, while keeping an eye on calories, choose to focus on macronutrient makeup. Protein, fat and carbohydrate are our macronutrients and different splits are advised depending on the diet. High fat, low fat, high carb, low carb, high protein, balanced intake, and so on. These are known and historic battlegrounds.
Still more advanced diets get into micronutrient makeup--micronutrients are vitamins and minerals, and they are crucial to the function and health of our bodies, though they themselves provide no calories.
Now, it may seem like calories, macronutrients, and micronutrients are all there is to a diet. I mean, what else is there to worry about? One answer is nutrient density.
WE ALREADY KNOW WHAT IT IS
Most people already have an idea of what nutrient density is. Don't believe me? Here's a simple task: choose the more nutrient dense option from each of the four examples below.
- 10 "Lifesavers" candies OR 1 1/2 cups of blueberries?
- 1 slice of pizza OR 1 cup of lentil soup?
- 1 pack of pretzels OR 1 cup of grapes?
- A 500ml bottle of Coca-Cola OR half an avocado?
Why is the latter "better" than the former in each of the four cases? Nutrient density.
Nutrient density is the proportion of nutrients in a food relative to its calories. Our ultimate goal, when it comes to diet, is to consume enough calories to provide the energy we need while at the same time getting all the nutrients necessary. In the examples above, the blueberries, lentil soup, grapes and avocado contain more nutrients for similar calories than their counterparts. They're more dense and better suited to that goal.
For example, a slice of pizza provides (approximately) 220kcals, along with 1g of fiber, 10g of protein, 2% RDA of Vitamin A, 8% RDA of calcium, and 10% RDA of iron. A cup of lentil soup, on the other hand, provides 180kcals, along with 6g of fiber, 8g of protein, 30% RDA of Vitamin A, 10% RDA of Vitamin C, 2% RDA of calcium, and 15% RDA of iron. Similarly, 500ml of Coca-Cola provides 210kcals and 53g of sugar, whereas half an avocado provides 160kcals, along with 15g of fats, 9g of carbohydrate, 2g of protein, and multiple micronutrients.
So, we all have an intuitive idea of exactly what nutrient density is. But let's sharper our understanding a little by examining what increases or decreases the nutrient density of a food or drink.
UP AND DOWN
There are three main ways in which the nutrient density of a food or drink is altered: added sugar, added fats, and processing.
1) Added sugar is one of the main ingredients in many high-calorie-low-nutrient foods. Don't worry too much about naturally occurring sugars in fruit and vegetables--most people don't overeat these foods. And don’t be fooled by “natural” sugars like honey, maple syrup and molasses. They're not that much better. The impact on the nutrient density of a product that is “made with honey” versus one that is “made with cane sugar” is very similar.
2) Added fats (and oils, which themselves are 100 percent fat) come with many conflicting messages. Some claim that fats and oils are healthy and that they should be added to our diets. Others suggest that we should completely avoid oils and saturated fats. But there seems to be more consensus regarding refined vegetable oils that are rich in calories and low in nutrients: the more you add them to your diet, the more you are lowering the nutrient-per-calorie density of your diet. However, while a gram of fat contains more calories than a gram of protein or carbohydrate, some sources of fat provide essential fatty acids – "essential" because the body can’t manufacture them and they must be obtained from food.
3) Processing. Many of the foods we consume have been refined and processed, resulting in products with no fiber and water content. Foods containing a lot of fiber fill us up more because they take up more space in our stomach. When we have eaten enough, a signal is sent to the brain. By contrast, when we eat highly processed foods with low fiber content, they tend to take up less space in the stomach even though they contain more calories, and the message that we have eaten enough does not get back to the brain. This is one of the reasons why many ultra-processed foods are more likely to lead to over-consumption, further hunger and low energy levels.
These are a few ways in which nutrient density is altered, but how is it tracked, measured and formally quantified?
RANKING NUTRIENT DENSITY
Given that most foods provide multiple macro- and micronutrients, developing a formal quantitative system to rate the overall nutritional value of an individual food is a complicated task. Currently, there is no universal agreement on a ranking system for “Healthy” and “Unhealthy” foods. However, several competing systems have been developed to rank food according to their nutrients--nutrient profiling, The Overall Nutritional Quality Index and The Nutrient Rich Food Index are examples of this. Some things these systems are used for?
- They provide the scientific basis for dietary recommendations and guidelines.
- They help create standards for nutrition labeling systems.
- They support the evaluation of nutrition and health claims.
- They contribute to the formation of regulation surrounding food marketing and advertising.
Despite their differences, these systems all tend to promote foods that are affordable to consumers, produced sustainably, and nutrient rich.
Also, they all agree with the following:
- Fruits, vegetables, nuts and legumes have a higher content of vitamins, minerals, fiber and/or fatty acids per calorie. Their consumption is encouraged.
- Foods with lots of total fat, trans-fat, sodium and sugars have a lower content of vitamins, minerals, fiber and/or fatty acids per calorie. Their consumption should be discouraged.
In short: the former are more nutrient dense than the latter.
Contrast this last fact with another: we are overfed and undernourished. Many Western diets are said to be increasingly high in calories but nutrient-poor. This seems to be correlated to the fact that processed foods contribute to more than two thirds of dietary energy and nutrients consumed in high-income countries.
THE FOURTH WAY
Naturally, if you're reading this, I suspect you don't want to go down that road and continue that trend. You want to eat enough calories--not too many, not too few--and from those calories get the amount of macro- and micronutrients that is right for you.
For most of us, me included, a simple way to do this is to aim for more nutrient density in your diet. You don't have to forsake entire food groups, or go on the latest branded diet. Just do one, or a few, of these things:
- Add at least one extra serving of vegetables or fruits to what you would normally eat at each meal. A good strategy is to start every meal with a salad, steamed or roasted vegetables, or a bowl of vegetable soup. Make sure you eat enough. It is important that you include highly satiating plant foods along with the ones that are low in calorie density in order to meet your energy needs. Combine fresh vegetables and fruits with whole grains, legumes, or starchy vegetables in order to feel satiated.
- By planning our meals and making sure the bulk of the food we eat is coming from nutrient dense foods, treats and snacks will feel less necessary and therefore become less frequent.
- Be aware that fruit juices, soft drinks and other sugary beverages count as additional calories. We usually eat the same amount of food regardless of whether we consume them or not. Also, keep in mind that they are not substitutes for nutrient-rich and fiber-rich whole fruits and vegetables. Sodas have a nutrient density of zero.
- Eat sweets as part of your meals and avoid them as snacks. Eating dessert after a meal is a habit for many people. Enjoy your favorites ones occasionally and experiment with new options with fewer ingredients, or with single servings. If desserts with added sugar contribute to a high percentage of your daily calories, eat more at meal time. No need to scrap desserts altogether though: you’re not going to compromise your health if you have a moderate amount of sugar every now and then.
- Aim to reduce processed fats, heated oils and fried foods and instead consume the healthy fats that are a natural part of whole foods. Ground flax seeds, nuts, sunflower seeds, pumpkin seeds and avocados can be healthy additions.
- There is no such a thing as a “superfood” with miraculous properties. No single food will do super things. If your diet is excellent, no single food will be responsible for the benefits. If your diet is terrible, no single food can compensate.
The point is not that calories don’t matter. They do, but by shifting our focus to eating a larger proportion of foods that have high nutrient density, we will end up eating enjoyable food that leaves us full and satisfied, while at the same time consuming less total calories. Just like the concept of nutrient density itself, I suspect you already have an intuitive sense of how desirable an outcome that would be...