These two terms describe completely different aspects of food.
Nutrient dense foods can help you optimize your nutrition. Energy dense foods can lead to weight gain. Here’s how these two factors interact in a healthy diet.
Read More: Nutrition/Energy Density Cheatsheet
Nutrition Diva is hosted by Monica Reinagel. A transcript is available at Simplecast.
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Hello this is Monica Reinagel. Welcome to the Nutrition Diva podcast.
"Energy density" and "nutrient density" are two phrases that get tossed around a lot in conversations about food and nutrition. Both are really important concepts to understand. But they describe completely different aspects of food. Today, we’re going to explore the differences between them and how you can use them to choose the right foods for your goals.
But first, I had a question from Lina, who wrote:
“There are many collagen products in the market and I want to know if taking collagen of any kind can actually help improve skin, nails, hair, and joints or if I am just wasting my money. Also, how about the collagen boosters for the people who are vegan? Do those products actually help your body produce its own collagen?”
Lina, I am so glad you asked.
Collagen is a protein that is only found in foods or supplements that come from animals. (Thus, the emergence of collagen-boosting supplements for vegans, who can’t take collagen itself.)
Collagen is a structural protein, meaning that it’s mostly used to build the scaffolding (bones, cartilage, tendons, ligaments, skin) that contains all our juicy bits (blood, nerves, organs, and so on). We get collagen from foods, in particular things like chicken or beef stock (more fashionably known as bone broth). And of course, we can also get it from supplements.
One of the unusual things about collagen protein is that it is not a complete protein—which most animal proteins are. So, as a protein source, it’s not as high in quality as most other animal proteins. Taking collagen as a protein supplement doesn’t make a whole lot of sense to me. If you’re willing to use an animal-based protein, you’d get a lot more benefit (often, at a much lower cost) from a protein supplement made from whey or eggs.
Because collagen is such a big part of skin, hair, nails, and joints, collagen supplements are also sold as a way to improve the health of those tissues, perhaps reducing joint pain, plumping up your cheeks, or making your hair or nails stronger.
We tend to produce less collagen as we age and environmental factors, such as UV damage from the sun, can further speed the loss of collagen, resulting in things like achy joints, wrinkles, and thinning skin.
But another unusual thing about collagen is that it’s a very large protein molecule, made up of lots and lots of amino acids. So large, in fact, that it cannot be absorbed into the bloodstream as is. During digestion, it is chopped up into lots of smaller pieces, called peptides. So, simply taking a collagen supplement is not necessarily going to deliver more collagen to your skin or joints or nails.
Your body would first have to reassemble those peptides and amino acids into strands of collagen. But here’s the thing: the decrease in collagen production as we age is not necessarily due to a shortage of raw materials. It has more to do with the genetic program that unspools as we get older. Simply providing more of the raw materials, in the form of collagen peptides or other nutrients that are involved in collagen production (the so-called collagen “boosters”) isn’t necessarily going to increase collagen synthesis.
Picture a factory in which the workers are all getting older and moving a bit more slowly. As a result, they are able to produce fewer widgets per shift. Dumping more and more raw materials into the factory is not going to make those aging workers any faster. Many of you are old enough (or sufficiently into antique sitcoms) to remember the famous I Love Lucy episode in the candy factory. And if you’re not, you owe it to yourself to look it up on YouTube. That’s essentially what we’re talking about here.
That said, there have been a couple of small studies showing that collagen supplements resulted in measurable improvements in skin plumpness or elasticity. First, I just want to say that something that is measurable with scientific instruments may not be visible in the bathroom mirror. But, it’s also possible that additional protein that you’d get from collagen supplements (or the additional water that you drink with them) could have some beneficial effects on the skin.
Personally, I think the money you could spend on collagen supplements would probably be better spent on a good quality moisturizer (which holds moisture in the skin), sunscreen (which protects the collagen from destruction by UV rays), and a nutrient-dense diet, which will supply raw materials for your body’s collagen-producing factory.
Which brings us to our main topic: nutrient density and energy density.
Nutrient density refers to how much nutrition a food provides per calorie. If a food is high in nutrients but low in calories, we say it is nutrient dense. But obviously, terms like “high in nutrients” or “low in calories” are relative. Nutrient density is most useful as a way to compare two foods. If a food provides more nutrition for the same amount of calories (or the same nutrition for fewer calories), then we say that it is more nutrient dense than the other food.
A glass of orange juice has about the same number of calories as a glass of soda, for example, but the juice contains more nutrients. Therefore, the juice is more nutrient dense than the soda. But a glass of tomato juice has about the same nutritional value as the glass of orange juice for about half the calories, making tomato juice more nutrient dense than orange juice.
Comparing the nutrient density of foods can get a little tricky. One food might have lots of vitamin C while another might be high in folic acid. Can we say that one is more nutritious than the other? Not really.
A handful of systems have been devised for measuring nutrient density over the years. NuVal is one that was adopted by a lot of large grocery chains in the US but was discontinued in 2017. Guiding Stars is probably the most widely used system in US grocery stores today. Nutriscore will be more familiar to European listeners. The Food Compass (which I profiled in episode #642) was recently proposed as a way to measure both nutritional quality as well as things like the degree of processing.
Most nutrient density scores take into account a broad range of nutrients and adjust the scores so that a food that is reasonably high in a variety of nutrients ranks higher than a food that's very high in just one or two. Some systems also subtract points if a food is high in undesirable elements such as sodium, sugar, or saturated fat.
Although the different systems have their strengths and weaknesses, the goal is to help you choose foods that deliver more nutrition for the calorie. These systems work best when used to compare similar items, such as various breakfast cereals. They are not as helpful if you're trying to compare dissimilar items like a soup and a dried fruit, for example.
In a nutshell, the more nutrient-dense your food choices, the more nutrients you're going to take in over the course of the day. And if you're restricting your calorie intake, it's even more important to choose nutrient-dense foods, simply because you have fewer calories to work with.
Energy density, on the other hand, describes how many calories a food has relative to its size or weight. A cup of grapes has about 100 calories and a cup of raisins has about 400 calories. So we say that raisins are more energy dense than grapes. A tablespoon of butter has about 100 calories while a tablespoon of light cream cheese has only 30 calories, so butter is more energy dense than the cream cheese.
As a rule, foods that are higher in water (such as fresh fruits and vegetables) and/or lower in fat (such as reduced fat dairy products) have a lower energy density than foods that are lower in water and/or higher in fat. By choosing foods with lower energy density, you'll get a bigger serving for the same or fewer calories. If you're trying to lose weight, these foods can help you cut calories without feeling quite as hungry.
In other situations, however, foods with high-energy density may be exactly what you're looking for. Athletes, hikers, and astronauts might want foods that deliver the maximum number of calories in the smallest possible package. If you're struggling to gain weight (and yes, there are those who do), energy-dense foods such as dried fruit, nuts, and avocados, can help you increase your calorie intake without over-filling your stomach.
Finally, it's important to remember that energy density doesn't take the nutritional value (or nutrient density) into account at all. A tablespoon of peanut butter has about 100 calories while a tablespoon of jelly has only 50. Peanut butter is a lot more energy dense than jelly—but also a lot more nutrient dense. Even if you're trying to cut calories, I think you'd be better off choosing the peanut butter and finding another place to save 50 calories.
Because nutrient density takes both nutrition and energy (or calories) into account, it's probably a better guide for overall nutrition. Understanding energy density can also be useful if you're trying to minimize or maximize your caloric intake.
You might find it helpful to think of foods in four categories: foods that are high in nutrients but low in calories, foods that are low in nutrients and high in calories, foods that are high in both, and foods that are low in both. In fact, I’ve created such a grid for you and you’ll find a link to that in the show notes for today’s episode or by going to nutritionovereasy.com and searching the blog for the keyword “density.”
Nutrient/Energy Density Cheatsheet
Thanks for listening today. I’d also like to invite you to check out my other podcast. It’s called the Change Academy, where Brock Armstrong and I explore the art and science of behavior change. You can find it on all the major podcast platforms, so whatever app you’re using right now to listen to me, just head to the search bar and type in “Change Academy.”
If you have a comment or a question you'd like me to answer in a future episode of the Nutrition Diva, you can email me at email@example.com You can also leave me a message at 443-961-6206