This is an oversimplified article about your nutrition needs while you are running or walking. It is intended to help you start the learning process of nutrition. After you read this you will probably want to consult a professional nutritionist for their expertise knowledge.
When you train you burn about 100 calories every mile you cover. Several factors can make that number vary but to keep it simple let’s just say 1 mile = 100 calories burned.
Your body stores energy in your glycogen reserves and in your fat. Your body tends to have an easier time utilizing glycogen than fat so it tends to burn glycogen first. The bad news is that your glycogen capacity is limited to about 2000 calories. If you want to complete a 26.2 mile marathon your body is going to need about 2620 calories which means you are going to be 600 calories short.
You might be thinking “I’ll just run on zero glycogen and burn 100% fat” or “I’m only running a half-marathon and will be fine”. It doesn’t exactly work like that. Remember this is an oversimplified article and we are skipping over a bunch of the complex body chemistry info. If you run your body down to zero glycogen reserves you are much more likely to end up in the back of an ambulance than on a magazine cover showing off a fat-free body. Even half-marathoners should fuel while they are working out for on their longer runs. Many half-marathoners are making their bodies perform at 100% for over two hours. If you are going to be that tough on your body, it is only fair to be a little nice to your body and give it some nutrition. You want to train your body to become more efficient at converting fat into calories AND to also eat during the marathon because your body really does love glucose and glycogen.
Should You Eat?
To help train your body to become more efficient at converting fat into energy it can be helpful to run a few times on an empty stomach (aka being in a low glycogen state). The easiest way to do this is to do your midweek runs without any special nutrition planning. To be safe it is not suggested to do your long runs on an empty stomach. You should also try to minimize repetitive workouts on an empty stomach. Doing either of these can increase the risk of potential injury. In other words avoid going to extreme levels. A few runs when you are in a low glycogen state can help your body learn to more efficiently burn fat.
Ok, so you are now training your body to become more efficient at changing fat into energy. What is also very helpful for your body is to train your body to absorb new fuel while training. Your body is using all of its energy and blood to keeping your legs moving. We need to teach your body to divert some of that to your stomach so you can comfortably digest and absorb nutrition. To do this we are going to start eating small snacks or energy foods.
What Can You Eat?
You are looking for easy to digest calories (basically sugars), sodium, potassium, and maybe caffeine. There are a bunch of other stuff that you will see in energy foods but we are going to keep it simple in this article. There are energy gels, energy chews, energy jelly beans, energy cookies/bars plus a bunch of DIY foods that provide easy to digest calories, sodium, potassium and the option of caffeine (careful caffeine can help give a jolt but too much can be dangerous).
Energy gels tend to be the more common fuel. There are several companies (Gu, Power Gel, Hammer Gel, Stinger Honey, Cliff Shot and others) that produce a very wide variety of flavors (Chocolate, Vanilla, Berry, Espresso, Lemon, Mint Chocolate, Orange, Strawberry Banana, Salted Caramel and others). Be careful when choosing the flavor because some contain no caffeine, others contain regular dose of caffeine and some even have double caffeine. Each company produces a slightly different gel consistency and the same flavor can taste differently from company to company so you need to do a lot of testing to find out what works best for you. This is another reason why you should start fueling early in your training. If you see someone at the water stops pull out a flavor you haven’t tried, ask nicely if they can squeeze a little drop on your finger so you can test the flavor. TNTers are a friendly bunch that like to help each other. One of the more common complaints about gels is that people don’t like the jelly consistency or that it can make their fingers sticky.
Energy chews are a good alternative for people that don’t like the jelly consistency of energy gels. These are like chewing on special gummy bear like cubes. Just like energy gels there are bunch of companies and bunch of flavors. Gatorade chews are sold in most supermarkets so they are one of the easiest energy chews to find but most people prefer the other energy chews for personal reasons. One common complaint about energy chews is that some people don’t like spending energy on chewing these very chewy foods or that it gets caught in their teeth.
Energy jelly beans are made by Jelly Belly and called Sports Beans. Their nutrition is a little less than some energy gels and energy chews. This is a less common choice but if it works for you, go with it.
Energy cookies and bars tend to be a better fit for refueling after you finish running but if you really like them they are good enough to use as race fuel. Honey Stinger makes a flat waffle cookie with different flavor on the inside. Powerbars and Cliffbars are options but they tend to be slower to digest and get energy into your body.
For the more curious people there are some DIY solutions. You can put stick pretzels in a plastic bag or mix up some DIY energy gel or energy bar (just Google the recipes). Be careful with the DIY recipes, some of them – ok most of them taste horrible. Black strap molasses has a great amount of potassium and sugars but wow it tastes horrible. Rasisins are good but don’t really have any sodium. Dried fruit in general is good but it can make you need the bathroom.
Whatever you decide, make sure you thoroughly test it out multiple times before race day. You do not want any surprises on race day. You probably want to save your favorite flavors for the end of the race when you will be the most desperate for a happy reward to your body.
How to eat
Whatever you decide is the right match for you please remember to eat it with some fluid. Having some water or Gatorade will help speed up the digestion and also help to rinse out the taste from your mouth.
Some people eat every 30 minutes while working out, or every 60 minutes. Most of us fuel about 45 minutes or 4 miles. Don’t worry about being exact, do what is comfortable for you. When in doubt it won’t hurt and will probably help you to fuel a bit early. If you are going for a short run (less than 60 minutes) you do not to worry a lot about eating while working out. The longer your workout the more you will notice the benefit.
Where to Buy
The local running stores all carry a good selection of energy products. REI.com has a good selection and each month they discount their energy gels and chews of the month. Just don’t buy a large amount of any one type until you have tried it out. You will probably have a bad experience or a few bad experiences of bad taste, bad texture or the packaging makes too much noise while you are moving. That is ok. There are so many different options, you will find the right option for you. The only wrong option is to ignore nutrition on your long runs unless of course you like feeling crappy and/or seeing the insides of an ambulance.
ps If you talk with some hardcore runners you might hear different opinions and that is ok. All of us are different. There is different research that supports different and sometimes conflicting opinions. As we continue to learn more and more about the body it is probably wise to avoid extremes and to listen to your own body.