In early 1968, I was a guinea pig in David Costill’s first runner experiment with Gatorade. We ran 20-milers on a treadmill three days in a row with no fluids one day, water the second day, and Gatorade the third. It was an exciting and informative experience.

Ever since, I’ve been closely following research into marathon nutrition and performance. And a new IAAF summary—“Contemporary Nutrition Strategies to Optimize Performance in Distance Runner and Race Walkers”—is the best I’ve ever seen.

That’s in part because the authors are the best, including Louise Burke, Asker Jeukendrup, and Andrew Jones. Most similar sports nutrition reports are so academic and mired in science lingo that you need an extra dose of glucose before reading them. This one is different, and better. It doesn’t reference all existing research—just the best and most useful. It also contains 6 sidebar charts crammed with key findings, and broaches several topics (such as low-fiber pre-race eating, hyperhydration, menthol mints, and weight periodization) that rarely discussed elsewhere.

Also, thanks to a collaboration with the International Journal of Sport Nutrition and Exercise Metabolism, the paper is free to download and read—if you’ve got the time and interest (it’s 10 pages long). If not, I summarize the highlights below in a user-friendly form that will take you only five minutes to absorb.

In addition, the IAAF has produced 17 sports-nutrition infographics that are free to download (scroll down to the infographic section). These visual guides range from “Mouth sensing of carbohydrates” to “Preventing runner’s diarrhea.”

Sports nutrition infographic - Mouth sensing of carbs
Infographic: IAAF

Here’s the promised summary of the new paper’s best sports nutrition strategies for marathon runners. The promise? That these tactics can help you prevent or reduce the risks of: glycogen depletion, low blood sugar, dehydration, central fatigue, muscle damage, and heat illness in hot weather.

Carbohydrate loading: For 36- to 48 hours before your marathon, focus on eating high-carb meals. If you avoid high-fiber foods, you can limit marathon pitstops. You might also reduce body weight a little (to offset the weight you’ll gain from consuming carbs and fluids).

The hour before your race: In the 60- to 90-minutes before your marathon starts, eat a small carb snack like a bagel or toast with jam. At the beginning of your (light) warmup, take 350 to 600 mg of caffeine, depending on your body size. While warming up, consume a gel or a modest amount of sports drink. This sort of race-day routine is particularly important for early-morning marathons (which most are) when you need to refuel after an overnight fast.

In-race fuel: The first fueling studies indicated that you should strive for 30- to 60-grams of carbohydrate per hour of running. More recent research has pushed the upper limit close to 90 grams/hour—from gels or sports drinks—particularly if you have done higher-fuel training runs. In shorter races, such as a half-marathon, you should be fine with the “swish and spit” method that tells your brain you are getting fuel even though you’re not. It also reduces the risk of an upset stomach.

Sports nutrition infographic - Carbohydrate intake
Infographic: IAAF

In-race fluids: You don’t need to replace all the sweat you lose. Aim to keep your marathon weight loss to about 2 percent. For a 120-pound woman, this amounts to 2.4 pounds, or about 38 ounces of fluid you don’t need to consume. In at least one regard, the less you drink, the better. With smaller amounts of fluid in the stomach, many runners will experience reduced gastrointestinal distress. Be sure to avoid overdrinking, which could lead to hyponatremia.

Supplements: The IAAF experts recognize only five supplements that could help track and field athletes, and only two of these—caffeine and nitrate/beetroot—have potential benefit for marathon runners. The evidence for caffeine is impressive; that for nitrate/beetroot less so. Nonetheless, a number of studies have found that nitrate/beetroot can improve endurance performance. Recommended routine: Take the nitrate/beetroot for three-plus days before your marathon, and two- to three-hours before the race start. But first practice in training.

Sports nutrition infographic - caffeine
Infographic: IAAF

In hot weather: The hotter and more humid the weather, the more attention you should pay to proper hydration (but not overhydration) to help avoid an excessive rise in body temperature. You can lower your body temperature pre-marathon by wearing a cooling vest or drinking an ice slurry. (Think: 7-Eleven “slurpie.”) The effects are relatively short-lived, but there are times when every minute counts. Also, sucking on a menthol (peppermint, not spearmint) candy while running “can elicit a cold sensory perception in the brain,” say the experts. It’s always good to keep your brain cool.

More hot-weather possibilities: The runners in next summer’s Olympic Marathon in Tokyo could face unbearably hot, humid weather. This will frighten some into trying less-common strategies like hyperhydration with sodium or glycerol. Sodium and glycerol allow the body to hold more water for a short time, reducing the threat of dehydration. Both methods also increase GI risks. Not recommended for amateurs.

Periodization: Carbs and Weight: As I reviewed the IAAF paper, I was struck by several atypical sections—for example, an expanded view of “periodization.” Normally this term describes a staged approach to training: Start with endurance workouts (base-building), then add more speed later. But the IAAF experts seem to cautiously endorse two other forms of periodization: high-carb/low-carb fueling, and high-body-weight training followed by lower-body-weight racing.

Low-carb fueling refers to a technique that has grown more popular in recent years—doing long runs in the morning without pre-run fueling. This forces the body to burn more fats, simulating the low-glycogen and low-glucose state you’ll encounter beyond 20 miles on marathon day. For faster workouts, the IAAF experts strongly endorse high-carb intake.

Infographic - The benefits of training with low glycogen stores
Infographic: IAAF

On the subject of body weight: Everyone can see that most distance races are won by skinny little guys and gals. But skinny can lead to injury or illness in the months of hard training before your marathon, so some experts are beginning to recommend that you “train high, race low.” The high and low refer to your weight.

The rationale: You shouldn’t obsess about your weight when in heavy training. In fact, keep it above your best competitive weight to insure successful workouts and recovery. Then, as you taper for your most important race, let you weight drift lower. This will increase your vo2 max, a key to optimal endurance performance.

Of course, the East African superstars who win so many major marathons appear to do just the opposite. Studies indicate they are under-nourished during hard training, perhaps because they have access only to simple, modest-calorie foods. However, when they reduce training before a marathon, they presumably pack in the glycogen they require.

In other words, no single strategy works for everyone. That’s why the IAAF authors often write that “various practical and personal issues need to be taken into account.”

Smart runners realize this. They follow the science, sure. But even more, they experiment on themselves, and listen to how their body responds.

Amby Burfoot won the 1968 Boston Marathon. He offers KISS Training Programs (Keep It Simple & Smart) at RunWithAmby.com.