Fasted But Not Fast

Today marks four weeks after my Spring marathon in Manchester and I think this is the time to get back into some sort of structured (ish) training. I would have begun a little sooner, but I had my big two-day cycle ride last Thursday and Friday, so I needed to inverse taper on the bike.

I’m still feeling some after effects of that ride – internal bruises in the palms of my hand when I try and go into plank, for example. But I managed a long, very slow, run today, averaging 13 minute miles for just over two hours, so that was pleasing.

It was slow, even for me, for two reasons. I still had the ride in my legs, and I wanted to explore running without eating anything first. As I’m a bit of a geek around books and research that is running related, I had read about the idea of running on empty, or ‘fasted running‘. By that I mean not having breakfast first (although I did have a couple of cups of tea with milk) and not having any gels en route.

The theory is that you can train your body to burn fat a little more efficiently if you don’t fill up your carbohydrate stores. You have almost limitless stores of fat, so you won’t run out or bonk, in the same way that you might if you ran out of your sugar (glycogen) reserves. I think this only works for endurance stuff, the kind of exercise where you’re able to breathe comfortably enough, as it’s a slower process to get energy out of fat rather than sugar.

Whether this is good or bad to do is not a blanket, one-size-fits-all thing. But I thought it was worth exploring for me because I want to reduce my reliance on gels, as I think they’re a bit artificial. I also want to reduce my carbs generally: not give them up, because I love bread/pasta/rice/croissants etc, but to reduce the portion of carbs I have with each meal. There are people on the extreme end of this debate, like Professor Tim Noakes (The Lore of Running), who think that virtually all carbs are evil, but there are quite a lot of other people, like Professor Tim Spector (main man in the ZOE Covid health studies), who think that generally, people in the UK and US eat more carbohydrates than they need, but that individually, some people are worse at absorbing carbs than others.

Not all the researchers in this field are called Tim, and there is a lot of research – sometimes with conflicting outcomes, so I think it’s important to be a bit wary of making radical changes. However, recently one of my sisters found that she was close to being diabetic, and physically, she’s way fitter than me and very slim. Apparently South Asians have more of a propensity to develop type 2 diabetes in the UK, six times according to this report but when you’ve tried to keep yourself fit and strong, it’s a bit of a bummer to still be at risk.

Therefore, I’m just exploring things in my own diet a little more. I love food, and I’m hoping that by reducing those carbs a little now, I won’t need to completely give them up in the future.

My fasted run went surprisingly well. For the most part, I didn’t feel hungry or lacking in energy. I did take a gel in the last half hour of my two hour run because my legs were starting to tire but, oddly, it felt like quite an intense sugar hit, and it doesn’t do that normally. This is one run, and the next might be completely different for a variety of reasons, but I will continue to experiment.

I’m not officially marathon training yet, so it’s a good time to try these things out. At the same, I want to get back to a nice base level of consistency so that when I do begin the training again, it’s not a shock to the system. I’m still deciding what that will look like, but I have a ball park of 25+ miles a week on a regular basis. That’s the plan anyway. It’s always hard to stay focused without a specific immediate game plan so I need to create a little bit of a goal, and that number is good enough for now.