# How far can one cycle without food? [closed]

What is the furthest anyone has cycled without food in an official race setting?

• Gotta ask; why do you want to know? Why would anyone want to see how long they could go before collapsing from de-hydration / starvation? Or is this a bid for a tumbleweed badge? ;-) Aug 10, 2015 at 1:55
• @renesis I like the way you think! ebrohman already has one tumbleweed badge; these comments have spoiled the next one :-) Aug 10, 2015 at 5:48
• Aww snap, yeah he does! Aug 10, 2015 at 15:28
• this is more related to biology than cycling. It very much depends on the nuances of each individuals physiology. The basic amount of energy required to bike a given distance is easily calculable as it the power consumption to achieve that distance in a given time. This can essentially be broken down into the biology question of "What is the longest the human body can go at [x] power consumption without eating". The root of the question is nonspecific to bicycles
– Jim
Aug 12, 2015 at 0:40
• I'm voting to close this question as off-topic because it isn't about cycling, it's a medical/biology question. Aug 13, 2015 at 3:40

Is the question about non-stop cycling or just riding over several days or weeks? For non-stop cycling it’s less about starvation and more about the maximum power you can get from burning body fat.

For the Race Across America the record (without any food restrictions) is 27km/h average over 4860km in 7d 16h. Since stopping and sleeping is allowed (though discouraged) on the RAAM I searched for longest time spent cycling non-stop. A record I could find was George Hood who spent about 178 hours over eight days riding a spinning bike. They state a distance of 2,016 miles (3,244.438km) though I don’t know what kind of conversion factor they use (since you obviously don’t move while riding a stationary bike the only meaningful number would be average power or total energy output). If we just trust that number we get an average speed of 18.2km/h which is really slow for road biking on flat terrain.

I don’t know what the limiting factor for such extremly long distances is, but at such relatively low speeds it should be possible to depend on fat alone without slowing down much. There are endurance athletes who deliberately stay on a low-carbohydrate diet to force their bodies into Ketosis while still training many kilometers per week.

Thus I doubt that food makes much difference for low-intensity, very long distance bicycling.

For bicycling until starvation the limiting factor is available body fat. With 400km per day you’d need about 8000kcal (assuming 16h of bicycling at 25km/h with 400kcal per hour (-> 6400kcal) and 1600kcal basic requirement) per day. Which is 888.9g of fat per day. Thus with 20kg of fat you could go for 22.5 days yielding 9000km.

• +1 for calculating total possible distance on body fat alone Aug 12, 2015 at 17:35
• If you went 22 days without eating you'd barely be able to stand up, much less cycle. Aug 13, 2015 at 10:55
• Why? I’ve never tried it but as far as I know the human body can work pretty well with body fat alone, especially after you’ve adapted to ketosis. Maybe someone else can shed some light on how much (if any) excercise one can do during starvation. Aug 13, 2015 at 12:00

This is a difficult question since it partly is reliant upon your excess weight and the speed you are riding.

But as a general rule no more than 10 miles before you eat the first time and every five thereafter. You have to keep food in the assembly line because it takes an hour or so to get into your bloodstream and it is slow to spread. So if you start a century completely recovered and you're moving along well, if you eat and drink well you will still finish the ride tired from insufficient nutrition. The lower down your performance curve the less chance of this happening.

You can actually calculate the number of calories you require for a particular distance using weight and speed and using an efficiency factor to know exactly how much you need.

• This is a bit excessive... eating every five miles. On a three-hour ride, covering 50 miles, my Garmin (informed by a heart rate monitor) tells me I am burning 1800-2000 calories. Aug 11, 2015 at 22:44
• There is some good info in your answer pertaining to nutrition and keeping ones' 'assembly line' full. However, there is no info about a foodless/waterless journey that actually happened. Also, it would be helpful to myself and others if you put the calorie calculation you mentioned in your answer. Aug 11, 2015 at 22:47
• This doesn't answer the question! Aug 11, 2015 at 23:32
• I have (when I was young and stupid) done 100 miles without eating. Aug 13, 2015 at 0:33