Carbenflarb III: Starting Runs Under-Carbed Is a Really Big Oopsie

Overtraining, faulty peaking, inadequate taper, positive splits, under-hydration, too much, too little or the wrong electrolytes, testing new shoes and fuels in a race, hypothermia because I didn’t wear my warm winter woolies.

I’ve done them all – and a lot more besides.

One of the worst mistakes I’ve made, measured by sheer energy-killing, joy-killing results, is starting a run inadequately carbed.

For years, I had the notion that if I ate very little carb when I wasn’t running, and carbed-up during my runs, I would lose weight and run well.


I believed the body needs a VERY long warmup – because it often took 40 minutes before I started feeling truly ready to run. My mistake was not realizing I was under-carbed going into my runs, and that it was taking 40-60 minutes for the fuels I ingested to fully replenish my carb-starved legs.

When our carb reserves run low and we try to run, the body is forced to burn fats for energy, and unless we have a rare talent for converting fats, we feel awful. That’s because hyperketonemia – elevated levels of ketone bodies in the blood caused by low levels of liver glycogen – doesn’t feel good.

A good example is a recent long run.

It was awful – after 30 minutes, my body was whimpering, my legs were tired and sore, my brain was fogged, and my heart was unenthused.

At an intersection where I could either go home or press on, I prayed my tuchis off and resolved to continue, because it felt like the right thing to do. Also, I wanted to learn if my tiredness was indeed due to insufficient carbs, or something else.

If I was under-carbed at the start, I should feel better as the carbs I was ingesting “hit my legs.” And that’s what happened.

An hour and 15 minutes into the run, my legs felt stronger, my brain was clearer, and my mood picked up.

Okay, I’m a believer. So how much carb do we need to take before we run, and when should we take it?

Research supports the idea of taking 200-400 calories of complex carbs 3-4 hours before we run – e.g., pancakes, bagels, etc. – and then a short snort of simpler carbs perhaps 30-60 minutes before we run, e.g., a packet of gel or a banana.

Here’s advice from “The 10 Biggest Mistakes Endurance Athletes Make, an article on the Hammer Nutrition website:

The goal of pre-exercise calorie consumption is to top off your liver glycogen, which has been depleted during your sleep. Believe it or not, to accomplish this you don’t need to eat a mega-calorie meal (600, 800, 1000 calories or more), as some would have you believe. A pre-workout/race meal of 200-400 calories—comprised of complex carbohydrates, perhaps a small amount of soy or rice protein, little or no fiber or fat, and consumed three or more hours prior to the start—is quite sufficient. You can’t add anything to muscle glycogen stores at this time so stuffing yourself is counterproductive, especially if you’ve got an early morning workout or race start…. If that’s not logistically feasible, have a small amount (100-200 calories) of easily digested complex carbohydrates 5-10 minutes prior to the start.

Those are the basics. Yet, as in all things running, there appear to be wide individual variations in how well we metabolize carbs.

Should we emulate ultra legend Yiannis Kouros, who shoveled down carbs by the bucket?

One of the most incredible things about Kouros is his ability to assimilate calories while running. During a six-day race from Sydney to Melbourne, Kouros’ intake was monitored and described in the Lore of Running. He was said to have managed to take in 15,000 calories the first day, 12,000 the next, and 7,000 the third day. During the Phidippides run that traced the Athenian messenger’s route from Athens to Sparta (and back) for a total of 300 miles, Kouros consumed half of his calories as Greek sweets, eating every 20 minutes, and enjoying baklava, fresh creamy custard, and honey cookies. – From “On the Trail with… Yiannis Kouros,” Running Times

Or should we copy Ian Jackson, a roommate of mine in the early 1970s, who once ran 140 miles in seven days, 20 miles a day, at a hard pace (6:30 to 5:00 per mile) over tough hills while fasting on plain water the entire time. Ian obviously had a phenomenal ability to convert stored fats, perhaps the result of good DNA and his many years of competitive swimming.

The Kenyan elites are known to consume over 75% of their calories from carbs, compared to just 49% for U.S. elite runners. (Source: Run to Win: The Training Secrets of the Kenyan Runners, by Jürg Wirz) If you’re a high-mileage runner, it might not hurt to experiment with doing likewise.

Probably the safe answer is to eat “just enough.” Overdoing carbs is dangerous. If we eat too much while running, it can tie up our gut; and the body packs away any carbs it can’t metabolize right away by storing them in our butts and guts.


Starting my runs well-carbed is working nicely. Earlier this week, I carbed-up several hours before a 30-minute run by eating pineapple and half a banana mixed with Raspberry Hammer Gel and Ultima electrolyte powder. Although I had run hard for 90 minutes two days earlier and would normally feel like poking along (I am an old putz), I ran with excellent energy – my legs were a little sore from the hard run, but they were full of energy.

Today, I ran over the Golden Gate Bridge, 90 minutes at moderate to high aerobic pace (80% to 85% MHR) and felt fine, though I had done an intense lower-body weight session two days earlier.

What’s for breakfast at our house? Pass the maple syrup and butter, please.

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