Carbo Loading – who needs it, and how to do it
By Susan Bowerman, MS, RD, CSSD
Have you heard of carbo loading? It’s a potential energy booster for endurance athletes – but for everyday exercisers it could lead to weight gain. Here’s the lowdown on carbo loading.
If you were to sit down for dinner with a bunch of runners the night before a marathon, chances are good they’d be chowing down on carbs – lots of them. You’d be surrounded by people eating heaping piles of spaghetti, rice, potatoes and bread – all in an attempt to top off their fuel tanks before the race. Most endurance athletes know that it takes a lot of carbs to keep their engines running – so there’s always a big push to pack in as much as they can the night before an event. But many endurance exercisers that I talk to don’t think about what they’re eating for the last few days before a race – which is too bad, because it could make a big difference in how well they perform.
The idea of carbohydrate loading – or what’s technically known as “muscle glycogen supercompensation” – is fairly simple. During endurance events, working muscles rely on heavily on carbohydrate for fuel. Much of that carbohydrate comes from storage sites in the muscles, where it’s stored in the form of glycogen. When glycogen stores run low, it’s not uncommon for athletes to ‘bonk’ or ‘hit the wall’ as they start to run on fumes. Carbohydrate loading is designed to ‘overload’ the muscles with glycogen, allowing athletes to maintain their pace and exercise longer.
In order to maximize glycogen storage, it takes more than one carb-heavy meal the night before a race – ideally, you’ll start planning about six days ahead of time. The standard procedure calls for a gradual tapering of the amount of time spent exercising each day (usually with a rest day the day before) and then a big bump up in carbohydrate intake during the final three days – at this point, carbs should make up 75% or more of total calories. So meals will feature abundant amounts of pasta, rice, potatoes, oatmeal, tortillas, bagels, pancakes, fruits and fruit juices.
With proper carbo loading, the amount of glycogen packed into muscle can increase as much as three-fold. And, the better trained the athlete, the better the benefit. Endurance training conditions the body to put more glycogen into storage, and to do it more quickly, too.
Note, though, that I have been using the term endurance athletes. Carbo loading is only helpful for those who are regularly engaged in intense, continuous exercise lasting longer than 60 minutes. If your workouts are generally shorter than that, carbo loading won’t help you. The value of carbohydrate loading is in its ability to keep you going longer – it doesn’t allow you to workout any harder. And, if you use your daily stroll around the park as an excuse to pile on the pasta, you could end up just piling on extra pounds, instead.