Question: What's the deal with energy drinks? Do they really give you energy? Or is it just hype?
Answer: Most energy drinks, such as Red Bull, Monster Energy, Hype Energy, and Adrenaline Rush, contain at least one of several ingredients that claim to boost your energy levels: caffeine, ginseng, and/or guarana. Caffeine acts as a central nervous system stimulant, increasing the heart rate, respiratory rate, and blood pressure. Increased alertness and energy levels generally result, as does dehydration because caffeine promotes body water loss. Ginseng is thought to boost energy in much the same way as caffeine-stimulating the brain and heart, as does guarana, an Amazon berry that contains up to seven times the caffeine as a coffee bean. Remember, while caffeine is widely consumed, generally with minimal side effects, less is known about the potential ill effects of herbs or plant substances, so you should use caution when consuming drinks containing these products-especially when mixing them with alcohol. The stimulating effects of the energy drink can mask the effects of the alcohol, and prevent you from realizing how intoxicated you are.
Question: I'm confused... What is the difference between "nutrient density" and "energy density"?
Answer: That's a good question, because on first glance, the terms look very similar. But, there is a subtle difference. Energy density refers to how many calories (or energy) a given amount of food contains. Nutritionists often refer to low-energy density foods and high-energy density foods. For example, a roughly two ounce glazed donut is a considered a high-energy density food because it contains a lot of calories (about 200) compared to the same amount of say, baby carrots (about 30 calories in two ounces) - which is considered a low-energy density food. This means you could eat nearly a pound of carrots to get the same number of calories as a two ounce donut. Nutrient density, on the other hand, refers to the nutrient content a given amount of food contains. Using the same example as above, a donut would be considered a low-nutrient density food, while carrots would be considered a higher-nutrient density food. You get vitamin A, vitamin K, and some fiber from carrots while you get relatively few nutrients from a donut (mostly sugar and fat). Typically, high-energy density foods are low in nutrient density; however, sometimes foods can be both high-energy density and high-nutrient density. Nuts, for example, contain a lot of calories in a very small amount of food (one ounce of almonds contains 165 calories), but also provide vitamin E, calcium, zinc and magnesium.
Sara Wilson is a registered dietitian and a graduate student in Nutrition Communication at the Friedman School of Nutrition Science and Policy. She has a BS in Nutrition from Syracuse University, and worked as a clinical dietitian prior to coming to Tufts. Wilson is also co-editor of Balance.
