Your body needs energy whatever your activity is. Also when you just sit on the sofa all day some energy is needed to keep up the necessary functions of living, your heart, your brain and all other organs. If you’re more active you obviously need more energy. There are several forms of nutrients that your metabolism can use to get the energy needed. In this post I want to describe these sources of energy. This might not be new to you as you most probably learned it in school or heard it from your parents, but I think it’s important to always know these basics especially as a regular runner.
Energy / gram: 3.5 – 4.1 kcal
% of your energy intake: 50-60%
Found in: Bread, Pasta, Vegetables, Sweets
Carbohydrates are one of three essential nutrients for humans and should be your main source of energy throughout the day. It’s the easiest part of food that the body can process and use as energy source. There are different types of carbohydrates the simplest one being sugar. After you ate sugar it ends up pretty fast in your blood to ensure short-term energy supply of your body. There are chemically more complex carbohydrates that take longer to digest but work as energy supply for a longer time and make you feel sated much longer. Your body is capable of storing some amount of carbohydrates and use it together with fat to deliver energy. The liver can store approximately 150 grams carbohydrates which is used mainly to maintain a high enough blood sugar level. As energy reserve carbs are stored in you muscles (200 – 300g) and used when needed. You can increase these storages with endurance training, especially with the long run.
Carbohydrates should make up at least 50% of your daily energy intake. On days where you go running you need a bit more carbs in relation to fat and protein. You find carbohydrates in all kinds of sweet food that contain a lot of sugar. But the better source for carbs that are more complex and can easily be stored are bread, pasta and most vegetables. With these kind of food you also get your vitamins and other healthy nutrients.
Energy / gram: 9 kcal
% of your energy intake: 5-20%
Found in: Oil, Meat, Milk products, Nuts
Yes you need fat! It is together with carbohydrates the energy source that fuels your body functions. Earlier it was assumed that your fat reserves are only tapped when your body runs out of carbs. Now we know that our body burns fat as well as carbohydrates together all the time even if the level of carbs in your body is high. Fat has a very high energy density, one gram delivers 9 calories, twice as much as carbohydrates and proteins. Fat that is normally stored in your body, whether you’re overweight or not, usually contains enough energy to run hundreds of miles. Theoretically, because the metabolism cannot burn fat alone it needs carbs as well or proteins at least. Although you need to eat some fat you don’t need much. 60-80 grams are enough for adults. If you eat more fat than you need it gets stored in your body. So preferably you should take extra energy needed when you exercise with carbohydrates or protein.
There are also different kinds of fats, some healthier than others. You should try to avoid eating trans fats that you’ll find in milk products or in beef and lamb. Try salmon, nuts, avocado or some plant-based food products as a source of fat.
Energy / gram: 4.1 kcal
% of your energy intake: 15-35%
Found in: Meat, Fish, Milk products, Legumes
Proteins are the building blocks of our cells, it is what we are made of. Proteins have some very important functions in our organism including DNA replication, transportation and protection against micro organisms. Apart from that your metabolism can also use protein as an energy resource. The energy delivery aspect is not as important for protein as carbohydrates and fat make up the preferred source of energy. However proteins are also very important for athletes as they are needed for regeneration or if you want to do some muscle-building.
Good protein foods are lean meat like chicken, legumes and fish as well as legumes since these also contain the healthier kinds of fats. You’ll also find a lot of proteins in milk products and all kinds of meat.
As most of your energy comes from the foods you eat, it’s good to be aware that also some might come from drinks. Fruit juices and sweet beverages contain quite some carbohydrates and milk based drinks contain fat and proteins. Most runners also know sport drinks like Gatorade, Powerade or Isostar that help you fuel and stay hydrated during a run. These are a great help during longer races when your stomach is not as efficient processing solid foods and you still need to refuel.
Of course nutrition is a huge topic and there are much more important nutrients to discuss in further posts. I just wanted to start with an overview of the main sources of energy in this one. What are the topics in nutrition or diet that you’re interested in? Leave a comment or use social media to share your thoughts!