Gut health expert Professor Tim Spector has issued a stark warning about the dangers of excessive fasting. Speaking on Richard and Izzy Hammond’s podcast ‘Who We Are Now’, the King’s College London professor explained that prolonged fasting could damage the gut lining.
During the podcast, Izzy queried whether microbes would consume the body if one didn’t eat at all, asking: “Would you eat yourself?” To which Professor Tim simply replied: “Yes”, before elaborating on the process that occurs during sleep when microbes become active.
He described how, typically, an overnight or 24-hour fast can be beneficial, saying: “Every night you stop eating…is that if you stop eating all these speeded up microbes and these other guys come out, like this cleaning team of specialised microbes that aren’t interested in bits of food, they tidy up your gut lining, because your gut lining has little bits of sugar.
“They nibble away at your gut lining and tidy it up, so generally, if it’s just an overnight fast or 24 hour fast, you get a nice haircut on your gut lining which makes it much more efficient, much better for your immune system.”
Professor Tim added that while a clean gut is desirable, overdoing it with longer fasts can lead to problems: “Everyone’s really happy to have a nice clean gut every night and if you overdo it, if you do a three or four day fast, they can eat so much you might start getting leakiness in it so you can overdo the fasting.”
Striking a healthy balance is crucial when it comes to eating habits, as Professor Tim points out: “It’s trying to get this balance right so that’s why doing anything to excess always has some risk attached to it, but what you should be doing is not snacking late at night to give your gut time to recover and that’s much better for your immune system, for your metabolism.”
Some people have subsequently asked if intermittent fasting is safe.
The answer isn’t straightforward. Results vary greatly among individuals, influenced by dietary choices, timing of meals, and duration of fasting periods. Professor Tim isn’t alone in cautioning against taking intermittent fasting to extremes without proper understanding.
Nutritionist Louise Pyne speaking to The Standard highlighted this: “One intermittent fasting study, which restricted participants to intersperse daily caloric restriction with unrestricted eating actually found that participants ended up eating more on the unrestricted days in anticipation of having to fast the following day, and furthermore, they also ended up exercising less.”
She suggests a gentler approach may be preferable for many: “A more relaxed version of intermittent fasting, which revolves around timings as opposed to calorie counting might be more achievable for most people.”
Pyne explains the potential benefits of this approach: “Keeping your food consumption within a 10 hour timeframe which means eating dinner slightly earlier and pushing breakfast to mid-morning has been shown to improve cholesterol levels, reduce weight and lower blood pressure in scientific studies.”
Fasting might just be the secret to a longer life, but it all hinges on the duration and timing of the fast. Dr Julia Jones has revealed some intriguing insights on the matter, suggesting that a well-executed fast could potentially extend one’s lifespan by two decades.
Speaking on This Morning, she advised: “Just to give our system a rest, so try and leave 16 hours overnight, fasting, and then eat within an eight-hour period.”
Dr Jones further explained the benefits of this approach: “A lot of research is now showing that we’re just eating too often, and we’re eating the wrong things obviously, but we’re eating too often. To give your digestive system a rest, and let other cellular pathways and important housekeeping processes kick in, can help reset those cells.”
