Advice on running a full marathon only 4 weeks into my first Keto experience

(Peter Michael Nielsen) #1

Hi all - greeting from Copenhagen, Denmark…:smile:

I’m planning to run Copenhagen Marathon in about 3 weeks and would so much like to get some advice and thoughts on how to get about it from now and until race day.

I’m 54 years old, 6 ft hight and my Garmin weight currently says 165 lbs.
I have been running on a regular basis for +25 years and been doing marathons since 92 so I guess that you could call me an experienced runner.

Here in 2019 I’ve started the year with doing a lot of running and decided to push hard on endurance training for the first 3 months and then increase intervals/fartleg for 4-6 weeks leading up to the race and then slowing down a couple of weeks prior to race.

Fast forward to start of April. After 5 days of recovery where I indulged in anything related to sugar (candy, cakes, soda and so on) I ran into an old friend that I’ve not seen for maybe 5 years and I was really surprised to see how much weight she had lost (plus 60 lbs in 2 years). She had been struggling to loose weight for the last 10 years and had finally been able to to this by turning here attention to LCHF/Keto. The meeting got me curious on all the benefits she mentioned and got me thinking if I could benefit from this as well so I decided to give it a try as well.

Today I’ve been on my first LCHF/Keto diet for 14 days and so fare it’s been an interesting journey.

Since day one I’ve lost 10 lbs which to me is quite a lot. My fluid % have interestinly gone up from initial 61,4 % to 64,6 % this morning so I guess my hydration is okay. BMI was initially 23,5 and today is says 22,1. I’m trying to balance my intake to 70/20/10 (fat/protein/carb) to try to get into ketosis as soon as possible. After 10 days I think I was hit with the Keto flue. Energy level is fine. The BIG change I’ve experienced so fare has been in my running. Started running again day 3 into the diet and was really surprised to experience how tired my legs felt.

So to make a long story short (sorry for long intro) my assumption is that if I stick to my new diet my running performance and recovery will gradually improve again when my body has adapted to fuel on fat instead of sugar…? The thing is that I would really like to stay on my new diet and not carb load like I’ved been used to. My racetime is normally about 4 hours and I don’t care if my first ‘Keto Marathon’ will be slower…:sunglasses:

Regards, Peter


Hej Peter
It’s totally possible to do…but…you’re talking about running a non carb loaded marathon just 5 weeks into keto. You’re happy if it’s slower but would you really be happy with maybe 4.5 to 5.5 hours. If you really want to stay keto you could carry on but make sure your pace is slower right from the start. Have you done any fasted runs and how do your legs feel now while running? Maybe put walk breaks in and maybe take on less/different fuel than you’re used to i.e. no gels or you could carb up with things like sweet potatoes rather than pasta/bread. 5 weeks is not really long enough to be either one thing or the other. You’ll now be coming up to taper time so maybe try to focus on real whole foods and begin properly after your marathon.

(Scott) #3

Haven’t done a full but it is on the list (4 HM). My running demise started just over a year ago in a stupid low speed ski fall where I tore a ligament in my ankle. After 5 months I started back running and started keto (<50g) on 7/10/19. Normally I never walk but my legs felt heavy and I had no energy. This lasted for three months but I lost 20 pounds. At the three month mark I stopped losing but like someone flipped a switch I had energy again. Running daily again and building miles for a HM and beyond I hope.

(Peter Michael Nielsen) #4

Hi Amada
Thank you for replying. I’m not sure how many hours after a meal is considered a fasted run…? I’m eating 3 times a days (like before Keto) and usually I would go for my run in late afternoon sometime between 4 to 7 pm (before dinner). In the weekend where I normally do my long runs I try to hit the road sometime between 10 am and noon. The first 4 runs between day 3 and 10 my legs felt terrible (heavy and depleted) and then for the next 2 runs I’ve seen a gradual improvement - but legs are still tired. Yesterday I managed to do a few intervals without burning out so it seems like my legs are adapting. During my regular runs I only fuel on water (before and after training). For weekend runs (+20K) I would sometimes use 1 gel besides water during training and then have a protein shake after my run. I only started to use gels about 10 years ago. Before that my fuel would only be water and the occasional banana…:grimacing: But I get your point about being in between stages. I would probably not mind doing a slower race than normal but how slow is acceptable…

(Peter Michael Nielsen) #5

Hi Rclause,
thank you for sharing info. It’s this ‘energy switch’ I aiming for. Currently I’m having a hard time understanding when this kicks in…?? From reading several posts in this forum it seems like it quite individual. Would love to know if you can speed up the process by training in a specific way (Aerob/Anerob) or doing less or extra miles and so on. Good luck on building up for next HM and beyond…:smiley:


Peter - there isn’t always the flick of a switch on energy. Definitely everyone is different. By fasted, I meant running without having eaten for 12+ hours. I would get up in the morning and run 20 miles (32km) with water only. I really upped my mileage quickly which I think helped me fat adapt quicker. I remember going for a 12 mile run. I walked home after 8 but the following week I completed the 12 albeit very slowly. I have just run 10 marathons in 10 days but obviously at a slower pace without any carbs. You’ll need to experiment with a speedy marathon and carbs but I think after this one probably. Good luck.

(Peter Michael Nielsen) #7

Hi Amanda - awesome that you could do 10 marathons in 10 days on carbs only…:fist: Would love to be able to achieve something like that. Have met some very strong and persistent female runners in the last few years and seems like you girls are pushing the boundaries at the moment…:sunglasses: Should I understand it that running fasted would help to improve performance on endurance races…? guess I could try this option without to much fuss. You know I’m one of those runners that have been on oatmeal every morning for the last 30 years so switching to Keto breakfast has probably been my biggest hurdle so far…:grimacing:

(Scott) #8

If I am not mistaken she did this awesome feat without carbs.

I just got back from a fasted 5 mile run and stopped on the way back at the gym to do a set. Heading out to get a truckload of mulch because I just don’t feel hungry and am full of energy. KCKO

(Peter Michael Nielsen) #9

Hi Rclause - of course you’re right…I wanted to say ‘on water only’…:upside_down_face:

2 days I had a decent 10K run and though that I would bump it up this morning by going for a slow 20K. Already after 2K I had very little energy and had to stop after just 7K…!! It felt like I was carrying a 40 pound sandback on my shoulder while running…:hot_face: Just 6 weeks ago I could run 20K without being on top so mentally it’s very tough to go through this fase. Today I’m 18 days into my Keto Journey and I guess that I have to accept that this transition will take time. Still loosing weight so I guess my muscles are taking a beating at the moment.

(Scott) #10

This is it! I called it lead legs, it was a struggle just to pick them up for the next step. I was starting to doubt keto because after two months this can’t be right. I went out one morning and thought “this doesn’t suck anymore”. Just finished a six mile run so I am slowly adding to my base. You may be able to add some carbs pre-race and burn them off with delaying your progress. Or if you are like me be stubborn and power through.

(Edith) #11

The fat adaptation is a gradual thing. You slowly feel less and less lead-like over time. Unfortunately, you don’t just wake up on day and say, “Wow! I must be fat adapted.”