Eating For Less Than 12 Hours A Day May Work Even Better Than Fasting And It’s A Lot Simpler

The benefits of intermittent fasting are (fairly) well established, but if skipping entire meals isn’t your style, there’s increasing evidence that just keeping your daily food intake to a 10-12 hour ‘window’ could improve everything from health to endurance – and muscle. RSNG tried it out…

How wide is your eating window? Assuming you’re like most people, it probably creaks open with a coffee at about 7am, then stays open on a constant cycle of grazing throughout the day, until you get have dinner anywhere from 6-8. Maybe you have a glass of wine or a beer to relax after a long day, or a bit of hot, buttered toast before bed. That’s around 15-16 hours – almost all of the time you’re awake – and for some bodybuilders, who’ll deliberately pound a casein shake or some oats before bed to stave off overnight muscle loss, the window’s even bigger. But is that approach actually good for you?

Daylight Humans At least a few high-level researchers think not. Humans, they point out, are diurnal – we’re active during the day, with metabolisms to match. A number of factors, but mainly light exposure and food intake, regulate the activity of enzymes in our vital organs, helping to process and metabolise glucose and fatty acids, as well as controlling insulin and muscle repair and the immune system, among other things.’

Narrowing your eating window to 9 hours may up endurance, insulin sensitivity and gut health

‘Eat outside of a roughly 12-hour long window, some research suggests, and these enzymes start to go off-road; blunting the body’s insulin response, causing muscle wastage, and making you fat. But there’s more. Dr Satchin Panda, one of the key researchers in the area, suggests that narrowing your window further – to 9 or 10 hours – might have further beneficial effects, from upping insulin sensitivity and giving the gut time to repair itself to increased endurance.’

It’s relatively early days for this research, but time-restricted eating (TRE) at least sounds a lot easier to manage than more strict intermittent fasting – and more sustainable over the long term. And with an ever-expanding group of self-experimenters tracking their own timed feeding via Dr Panda’s app, Mycircadianclock – you take photos of your first and last meals, which are automatically uploaded and time-stamped – RSNG decided to join them for at least a month. Here’s how it went…

TRE Day 1: Get up at 7am, no coffee. This is a tricky one: though intermittent fasting typically allows (black) coffee, caffeine is technically a ‘xenobiotic’, or an unfamiliar substance that your liver enzymes have to process, so it kicks off the hormonal cascade too early. Instead, I drink a big glass of water to keep me going until 8am, when I have breakfast. This isn’t too bad, and I power through until dinner at 7pm, followed by an early version of my usual ‘supper’ – Greek yoghurt with a bit of banana – to skid, Indiana Jones-style, under the window before it slams shut at eight.

TRE Days 2-5: Mostly fine. Minor wobble on day four, when late dinner means I can’t fit supper in, but I still have to stay up late to finish a project with no soothing toast or tea. But otherwise, having water instead of a caffeinated drink first thing in the morning seems to make me more, not less alert, and staying off the late-night toast is a great guilt-buster.

TRE Days 6-7: The weekend! Indulge in a couple late-night beers and an unprecedented late-night toast: studies done on mice suggest that it’s possible to take two days a week ‘off’ TRE while retaining its positive effects. I don’t feel great afterwards, but that could be the beer.

TRE Day 9: Friends go out for an unplanned late-night drink and I have to switch to water because I frittered away my day off at the weekend. I am an idiot.

TRE Days 10-14: Have a late-night drink and supper on Saturday more out of habit than anything, but starting to not really ‘want’ one: I’ve realised that I never feel great even pre-bed. Starting to see my abs, but that could be thanks to a dramatic reduction in night-toast intake.

TRE Day 15: The start of the tricky bit. Though 12 hours is the recommended maximum for TRE, other researchers – including Dr Rhonda Patrick – report anecdotally better results from 9-10 hour windows. It’s theorised that delaying the start of eating during the day, for instance, can improve insulin sensitivity, while sticking to a small window can increase circulating ketones in the body, improving endurance. Unfortunately, this means I don’t get to have breakfast until 10am, which means making my wife and baby something at 8am, then hanging around to eat my own. I’m not exactly starving, but it just doesn’t seem all that practical.

I start skipping breakfast and just have a mid-morning snack with protein, nuts and fruit

TRE Days 16-27: New system: I start skipping ‘conventional’ breakfast and just have a mid-morning snack with protein, nuts and fruit in it. Technically, I could probably get away with a croissant – some evidence suggests that TRE can actually offset the effects of a bad diet, while (conversely) a better diet can mitigate the downsides of straying outside your window – but, to be selfish about it, you get a lot more hungry at weird times when you eat simple sugars. In other words, I’m eating better not because I’m on a diet, but because it’s the only way to stick to the window.

TRE Day 28: Lost a kilo. Abs actually visible. It’s not a controlled study, because I haven’t accounted for overall calorie intake, or the bad stuff I often eat late-night or early-morning – I’ve probably cut out 1,500 calories a week in toast alone – but I’m feeling better throughout the day, clearer-headed in the morning and less hungry at night. I’ll probably go back to having regular breakfasts – because I like them – but, overall, TRE feels like the smart, sustainable alternative to intermittent fasting, and a no-brainer way to steer clear of temptation. Can I do the full 12 weeks necessary to become part of Dr Panda’s study protocol? Time to find out…

WHAT NEXT? Watch this video on how to implement TRE in your own life, then download the MyCircadianClock app or Kevin Rose’s Zero app to get to work.


Comments are for information only and should not replace medical care or recommendations. Please check with your Doctor before embarking on exercise or nutrition regimes for the first time.