The Food Diary in the wild: running a marathon with lactose intolerance

How do you run a marathon with a dairy intolerance? Susan shows us, it’s actually not just manageable but actually easy!

Here’s how she used her diary to get her through training for the Dublin Marathon while managing her lactose intolerant stomach…


Every month in our newsletter we feature a food diary in the other words, we love to tell the stories of diary users: what they use them for, how they're getting on, their stories. You can sign up to read them first here

If you missed Susan’s story in our newsletter last month, here it is! Susan used her diary to conquer her lactose intolerance during marathon training. Read on to find out how she did it...

"Our marathon coach advised us to write everything down for training, and gave us a training plan (the printed sheet underneath my diary there) to follow, which I filled out diligently after each run.

I was really aware that I needed to eat properly if I was to get through this fairly intense training season, and my lactose intolerance has a habit of giving me a sickly stomach at the worst possible times. 

I was also trying out a lot of new foods to eat on the run. The diary was a great way to track what I was eating, how much water I was drinking, and what foods didn't agree with me. Thanks to this I didn't have a stomach cramp the entire way around the Dublin Marathon course! 😍😍😍

My marathon day wouldn't have gone so smoothly without it - not just the day but the build up too. It was an intense training period and it would have been easy to skate from week to week without monitoring what I was eating and the suffering the consequences. But because I could look back on each week of food as well as my training diary, I could see what was working and what wasn't I can't tell you how chuffed I was to not have any cramps (or worse) on the day - worrying about the possibility of symptoms was a serious mental barrier to trying longer distances in the past.

The most useful part of the diary for me was having enough space to write out everything I've had in a day, and to list associated symptoms. I've used trackers for things before where there's barely space to list everything in one meal! Plus I was very happy to bring the diary with me everywhere because it's BEAUTIFUL (and I'm a librarian and stationery geek, and love beautiful paper things!)”

Thank you Susan! If you love a good nosy into other people's food diary habits as we do, don't forget to sign up to our newsletter and they'll drop straight into your inbox! 

Ps: if you're a diary user and love it so much that you want to share your story, email us at with the subject 'my diary story!'. We love love love reading and sharing them!