Can I really fuel my rides purely by burning fat rather than carbs (or, technically, glycogen) and do so more efficiently and with greater recovery?

Doctors used the ketogenic diet in the 1920s as part of a therapy plan for people with epilepsy, although the origins of ketogenic medicine may date back to ancient Greece.

For randonneuring we do not need immediate bursts of energy—instead we should maintain a consistent pace.
This is possible with little-to-no carbs.

Here’s what the experts suggest:

Focus on Your Macros

Some get carried away by the specifics and insist on constant testing to see if it is working:

. . .  if someone is telling you he’s doing the Keto diet and you just have to try it, but he’s not testing himself, he’s not doing it right.

Rather than focus on hitting a specific number of grams each day, Rob Raponi thinks it’s smarter to track your keto diet by macro percentages. 

Your caloric needs change based on your energy output anyway, and “the amount of energy expended [during exercise] means carbohydrates will constantly be depleted, leaving the body in a state of ketosis so long as the appropriate amount of fats and proteins are consumed,” he explains. 

Macro percentages will vary per person and situation, a useful ratio for the keto diet is:

  • 70-80 percent of your calories from fat, 
  • 15-20 percent from protein, and 
  • 5-10 percent from carbs. 

Be careful not to underconsume calories, which can lead to problems like constipation, energy decreases, and missed periods in women.

Heather Bruce does not believe it is necessary to follow a strict dietary formula but recommends general guidelines in her Life Recipe.
She says eat lots of:

  • Fat,
  • veggies,
  • nothing cold or sweet, and
  • limit carbohydrate intake

See How Long You Can Go Without Snacks

Those who are fat-adapted generally don’t need additional fuel in the first couple of hours of a ride.
“Even very lean individuals are thought to have plenty of energy to fuel long distances.”
(Of course, this is after a filling breakfast of something like eggs, bacon, and sautéed non-starchy vegetables two hours pre-ride.)

For longer training rides, a bag of high-fat walnuts is a good standby, but may not be needed.

Experiment With Your Fuel

Keto-friendly options that behave well with my stomach: 

  • Walnuts, 
  • cashews, 
  • pickles.
    (tip: Put dill pickles—and their juices—in an insulated tumbler you can store in your bottle cages to sip on for a still-cold hit of supplement-free electrolytes.)
  • sliced avocado,
  • cheese, and
  • nut spreads.

Everone’s needs are different so you must learn by trying it yourself. 

“All ketogenic diets have the same underlying principles, but the details of meal timing and snack choices can vary tremendously.”

You should be able to take in fuel on more of a delayed schedule than you would on a high-carb diet—about every 40 minutes instead of every 30.
This allows the fats to be absorbed without overwhelming your digestive system. 

“Because fats are more calorie-dense than carbohydrates—each gram of fat carries nine calories of energy as opposed to four calories of energy for every gram of carb–I would recommend eating slightly smaller amounts, less often” – Zandes

Hydrate, Hydrate, Hydrate

“Fat-adapted athletes still need to make hydration a priority, [as] excessive sweat losses will result in losses of sodium and potassium, which need to be replaced in order to maintain exercise intensity,” says Zandes.
The only problem? 

Gatorade and similar sports drinks aren’t on the keto-approved list due to high sugar count. 

That’s why, for those who need something more than water, the pickle juice can help—it’s chock-full of sodium and electrolytes to help recoup your losses. 

Or try low-carb, low-sugar Nuun Electrolyte tablets. 

“In theory, someone on a ketogenic diet is running off of these ketones for energy, so supplementing with them offers a quick and readily available source of energy similar to that of sugar,” he explains.

Popping a caffeine pill 20-30 minutes before your ride can also help shift metabolism to a more fat-burning state after 90 minutes of exercise, says Raponi.
Dosage recommendations vary based on your individual caffeine tolerance and how much of it you consume in your day-to-day, but Raponi suggests starting at a low dose of about 3 mg for every kilogram of body weight.
So if you weigh 180 pounds, that’s about 246 mg of caffeine.

Have a Reserve of Carbs

You never know what’s going to happen on the road. 

As prepared as you think you are, it can affect everyone differently. 

According to Brodie, there are some indicators that mean the diet probably isn’t working. 

“Usually the first thing is you have a big sap of energy—like someone flipped a switch and you just can’t go anymore,” he says.
“It’s not bonking; it’s like the pedals are turning but nobody’s home.”

Then comes the lightheadedness. 

If the dizziness refuses to dissipate despite more keto-friendly fuel and hydration, it’s time to turn to carbs, and having an emergency stash is helpful. 

Rather than shock the system with gels and chews, Brodie suggests cutting half a bottle of sports drink like Gatorade with water and chewing on dry dates. 

They have a similar glycemic index to a gel, so the body will respond similarly, but they also contain fibre and will have more of a gradual, long-term effect on your energy (whereas a gel would spike your levels quickly), he explains. 

Within 10 minutes or so, you should be able to recover and finish the ride strong, but take your time and don’t rush it. 

When you have to choose between ketosis and finishing a ride, it’s that diet that can be broken.

Road Bike Rider published this interview with attorney, certified Bulletproof nutritional coach, and road cyclist, Valerie Peterson of

Other links:


  • Mitchell Zandes, a registered dietitian and certified strength and conditioning coach in New York City.
  • Rob Raponi, a naturopathic doctor and certified sports nutritionist in Ontario
  • Heather Bruce, internationally recognised acupuncture consultant
  • Brodie MJ Glasgow Infirmary

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