24-hour fasting experiment

What is fasting?

In simple words, fasting = not eating. There are several of protocols used as therapeutic fasting or fasting-mimicking diets (e.g. intermittent fasting, alternate day fasting, calorie/protein restriction).

Why fast?

There have been many experiments conducted in all sorts of critters (from yeast to humans) to study the impacts of fasting. Results from both non-human and human studies suggest that fasting could extend lifespan, reduce oxidative stress and inflammation, prevent neurodegenerative disease, improve cognition, reduce cancer growth and enhance metabolic function, among other health benefits. The mechanisms behind those effects include the production of ketones and their role as an energy source for the brain, the reduction of blood glucose and insulin, and the stimulation of apoptosis (programmed cell death) and autophagy (cellular cleanup process).

The aim of this post is not to cover all aspects of fasting therapies, but to report on my n=1 experiment. If you’re interested in learning more about fasting/fasting-mimicking diets, here are some resources:

On to the experiment

I have been thinking about doing this experiment for a few years but life always got in the way. The opportunity presented itself when my husband had to travel for a job interview (I find it easier to experiment with my diet when he’s not around).

My last meal was Sunday lunch. I had had neck and shoulder pain for a few weeks, so I went for a massage, then came back home, watched a documentary and did some work. I drank several cups of warm water and didn’t feel hungry until 20:30ish. I did a short meditation, prepared my stuff for the next day and went to bed around 21:30. I was expecting having trouble falling asleep due to:

  • Not having done any physical activity
  • Being slightly hungry
  • Having trouble sleeping when my neck hurts
  • My personal heater (i.e. husband) being away

I was awake until 3:00. My alarm buzzed at 6:00, so I had a grand total of 3 hours of sleep. I tried to go back to sleep but couldn’t, so I decided to get up and go on with my day.

I got to work half hour earlier than usual. By then I could recognise the signs of full ketosis: a clear brain and low body temperature. Hunger came and went but didn’t last long. I contemplated having my morning coffee as per usual (after all, it has negligible energy and zero protein) but decided to stick to water.

The hardest part, surprisingly, was not flicking through Instagram food photos, but smelling my coworkers’ lunches around noon. I normally eat at noon but this time I had to wait until 13:00 to complete the 24 hours. I’d say the last hour was probably the hardest, also because I finished the work I was doing so had nothing pressing to keep me distracted. I ate my lunch plus a few handfuls of macadamias sprinkled with sea salt not because I was hungry, but to make sure I was making up for some of the calories that were not consumed during the experiment. I kept drinking water throughout the day.

That night I did a Krav Maga class as per usual, and surprisingly didn’t feel any shortage of energy nor strength, despite having slept only 3 hours and eaten just one meal within the previous ~30 hours. The lack of sleep didn’t hit me at all, but I’m not sure if I can attribute this to fasting.

Parting thoughts

From what I’ve read, I think there is compelling evidence to suggest fasting once in a while is beneficial. It makes sense that lack of energy intake would elicit a hormetic response and allow cellular cleaning processes to occur. It also makes sense from an evolutionary perspective that we should not have food in our bodies 24/7.

My plan is to implement fasting periods of varying durations whenever there is an opportunity (e.g. travel, periods off training such as dealing with injuries, etc.).

Intermittent fasting (IF)

Earlier this week two of my friends mentioned an article on intermittent fasting published by a local newspaper. Apparently mainstream media had just heard the news.

Intermittent fasting (IF) is not a new concept my any means, people have been fasting forever (our ancestors didn’t have access to food 24/7, and religious fasting has been around for a long time) and science has been running studies on the topic for decades. However it took a while for it to become “popular” in the nutrition/fitness circles. The first time I heard about it was 2007, but I didn’t pay much attention to it perhaps because the stuff that I read was a commercial program aimed at weight loss only. When I learned about all the health benefits associated to fasting I was keen on giving it a go.

Empty plate

So a couple of years ago I began by “scheduling” my fasts on non-lifting days, but I quickly realised it was not a very natural way of doing it. Granted, intermittent does not mean random but in my experience random works best for preventing adaptation (which BTW is why it’s a good idea to vary your training). So I ditched my plan and now just let it happen when it happens, for example when I’m not hungry in the morning, or when I fail to wake up on time and have to run in the office.

What happens when you fast? Basically your body switches from using sugar for energy to using fat, similarly to what happens with ketogenic (high fat, very low carb) diets. Therefore, your insulin sensitivity increases. Your body’s garbage collector (an analogy for my software development colleagues) turns on and recycles waste products in a process called autophagy. And many other benefits that you can read about on the links below.

On a practical level, this is what I get out of it: my thought process is clearer, I feel lighter, more awake and energetic. The occasional bout of hunger (usually triggered by reading food blogs) goes away quickly, mainly as a side effect of eating a nutrient-rich diet. On the flip side, I tend to get colder than usual, with a “minty” feeling on my skin.

So, does that mean that everybody should be doing it all the time? Well, no. As Robb Wolf often says, intermittent fasting is a tool, like many others. Sometimes you need a hammer, sometimes a screwdriver. It can help some people at certain times. Stefani Ruper has analysed the effects of IF in women in depth (see link below). Right now I’m only doing it very sparingly, and never when uni is on, because juggling study and work is stressful enough.

Note: while the article does a good job in introducing lay people to the topic, I find their meal plan suggestions rather disconcerting. They recommend having breakfast, lunch and dinner (where’s the fasting? in between meals?) based on the premise that “The best thing about this diet, I decide early on, is that fasting doesn’t mean not eating. It means eating very little.” Well… not really. Mat Lalonde says you can get the benefits of autophagy if you eat something apart from protein. I would assume it’d be better to stick to a ketogenic protocol (coconut oil, maybe some nuts or avocado, salad greens, etc.). Still, authophagy is only one benefit of IF, and I don’t imagine all of them would be present by almost fasting. Specially if you’re eating toast, baked beans, yoghurt, fruit, steak and salad, as the article suggests. They’re basically recommending a calorie restricted diet, with no real fasting going on.

For more information on the topic please check the following links:

The Myriad Benefits of Intermittent Fasting, by Mark Sisson
“…fasting once in a while seems to offer many of the same benefits of calorie restriction – you know, stuff like increased longevity, neuroprotection, increased insulin sensitivity, stronger resistance to stress, some cool effects on endogenous hormone production, increased mental clarity, plus more – but without the active, agonizing restriction.”

My Times Piece On Intermittent Fasting by Dr John Briffa
“On days where you’re intake of food is significantly reduced, it pays to emphasise foods that are highly nutritious and effective at sating the appetite. Protein and fat tend to pack most punch here, so appropriate foods might be fresh meat, oily fish, eggs and nuts, coupled with some green vegetables and salad for additional nutrients… Intermittent fasting has merit, I think, but it’s not for everyone. Those who should avoid intermittent fasting include individuals with a history of eating disorder and diabetics. Other individuals who are generally unsuitable candidates for intermittent fasting include those who are generally ‘stressed’ or have chronic fatigue. Stress can weaken organs known as the adrenal glands, and intermittent fasting can weaken these glands further, which may exacerbate symptoms such as fatigue.”

Experiments with Intermittent Fasting, by Dr John M Berardi
with Dr Krista Scott-Dixon and Nate Green

“Trial fasting is a great way to practice managing hunger… More regular fasting isn’t objectively better for losing body fat… More regular fasting did make it easier to maintain a lower body fat percentage… Intermittent fasting can work but it’s not for everyone, nor does it need to be. In the end, IF is just one approach, among many effective ones, for improving health, performance, and body composition.”

Shattering the Myth of Fasting for Women: A Review of Female-Specific Responses to Fasting in the Literature by Stefani Ruper
“Many women find that with intermittent fasting comes sleeplessness, anxiety, and irregular periods, among a myriad of other symptoms hormone dysregulations. I have also personally experienced metabolic distress as a result of fasting, which is evidenced by my interest in hypocretin neurons… Hypocretin neurons are one way in which intermittent fasting may dysregulate a woman’s system.
…I was struck by what seemed like an egregious sex-based oversight in that MDA post I linked to above. MDA cites this article as a “great overview” of the health benefits of intermittent fasting. This startled me because the article MDA cited was for me one of the strongest proponents of sex-specific differences in response to fasting. This occurred in two striking areas: a) women in studies covered by the review did not experience increased insulin sensitivity with IF regimes and b) women actually experienced a decrease in glucose tolerance. These two phenomena mean that women’s metabolisms suffered from IF. The men’s metabolisms on the other hand improved with IF across the board.”