How fasting taught me to reduce my exercise for more productivity

The science is clear: exercise is one of the best things you can do for yourself, preventing disease, raising energy levels, and improving mental performance. It can only support you to be productive. But can you do more than you need? If you’re fairly healthy but would like to be more productive you may be interested in what I discovered from a prolonged fast.

You know the dilemma: how to maintain a healthy weight or, let’s face it, not become over-weight since burning it off requires effort and isn’t always that enjoyable.  I must admit now that this is not something I struggle with. With my metabolism slowing down as I entered my fifties I was forced to adopt what for many would seem a fairly strict health regime involving a weekly 45 hour fast, time restricted eating, a healthy diet, regular exercise and activity, and prioritised sleep (since poor sleep can lead to weight gain). 

For the last five years I have successfully managed to keep myself to an assumed ‘optimal weight’ averaging 69kg (152 lbs). Every week I gradually add a few hundred grams each day allowing myself some indulgences on the weekend knowing I can afford to go into the red because my 45 hour fast (which starts 9pm every Sunday) will bring me back into the black again.  The week then repeats. My programme works and I’m happier and healthier for it.

There is only one drawback: the amount of exercise I have to do. It probably averages about 1.5 hours per week day when you factor in getting ready, showering etc (longer if I go for a sea swim) and this inevitably takes time I would be better off giving to my business.  By being my own boss I can allow for it, not least for its benefits to my mood and performance, but the net result is I usually end the week having worked fewer hours (virtually a whole day per week in fact) had I not exercised as much. For me personally it actually reduces my productivity. 

In mid-August an acquaintance inspired me to follow their example and do a four day fast, something I used to do three times a year a few years ago to give my physiology a good ‘clean out’ (there are many health benefits to fasting that for concision I won’t go into here). Anyway I gave it a shot, and fasted 90 hours, giving up only because I find two of more days too deleterious to my sleep; otherwise I felt great. Inevitably my regular 45 hour fast came up pretty quick after the four day fast. I was fairly active - it was the August Bank Holiday and I went walking and wild camping. By the time I ended it I’d only eaten during three days out of nine and lost 3kg.

I assumed I would put the weight back on and return to my usual weight of 69kg. But I’ve not done so, nor felt a strong need to. My body seems to have recalibrated itself to a calorie intake slightly lower than before. According to Chat GPT, as a result of a prolonged fast “the hunger hormone ghrelin (which spikes to signal hunger) tends to adapt downward. So when you do eat again, you feel full sooner and your hunger cues are weaker than before. Extended fasting can improve how your body responds to leptin and insulin, two hormones that regulate fullness. Many people notice that food feels more satisfying afterward, so they naturally eat less.” Fasting is would seem is the original weight-loss drug, and it’s completely free.

Feeling no great compulsion to eat more and noticing I didn’t feel the need to exercise as much as previously I’ve purposely chosen to keep myself to a lower weight averaging 68.5 kg (151 lbs) in a week.  (which is where it seems to have defaulted to though I’m aware it may creep up especially as cooler months approach).

The positive upshot of this (aside from saving a little extra money on food and er…toilet paper!) is that I’m more productive and working more hours because I’m exercising less than before. Instead of a 10km run, 6km suffices. Instead of that 30 minute workout, 20 minutes feels enough. I’m not as strong as before and have slightly less stamina but I’m still plenty active with good energy levels. And I love my food just as much as before. I just don’t feel the need to eat quite as much of it. It’s been a win-win.

The experience has changed my assumption about what constitutes one’s optimal weight and made me realise it is largely subjective and influenced by one’s lifestyle.  According to Chat GPT “a person’s optimal weight is the weight (or weight range) at which they are metabolically healthy, physically functional, and at lowest risk of disease—often corresponding roughly to a BMI of 18.5–24.9, but ideally adjusted for body composition, genetics, and lifestyle.”

I had believed my ‘optimal’ weight averaged 69kg based on assumptions about what I needed to do to maintain my health and be productive, including the amount of exercise I needed to do and food I needed (and would want) to eat over an average week.

Since financial necessity requires me to spend most of my hours at a computer screen I now realise I’m better off trying to maintain my current slightly lower weight of around 68.5 kgs (average) by eating a little less and doing less exercise because this saves me time and helps me be more productive.  Had I not done the prolonged fast I wouldn’t have discovered this or made the correction.

So what learning from this would I pass on?

• For a small proportion or people with good eating habits who’re not overweight it can be possible to do more exercise than is strictly necessary, bearing in mind that exercise generally increases appetite.

• Periodically testing your assumptions about what you need to do to be healthy and productive can provide you with new information and enable you to make corrections to your lifestyle that may benefit you (such as increased productivity for negligible health cost) that you’d miss if you didn’t test them.

• Doing an occasional prolonged fast such as three to five days can help your body to recalibrate and be very illuminating. Research also suggests it’s very beneficial, though consulting an expert such as your GP beforehand is often advised (I would also recommend drinking water with zero calorie electrolytes while fasting).

In conclusion, working out and maintaining your ideal weight takes a bit of effort and quite a lot of discipline and is a balancing act based on all the factors (specific to you) that come into play, but there can be clear benefits and rewards for doing so.  Good luck!

Headspace Coaching Plus is healthily obsessed with health and well-being, and always happy to coach others in how they can improve theirs. If this is of interest get in touch, and if you’d like to receive the occasional useful insight, inspiration, and even recipe please subscribe to my newsletter.