We're not protein-deficient
What I told Dr Karan Rajan about light, timing, and the clock inside your gut.
A few months ago I sat down with Dr Karan Rajan. A man who has cultivated a reputation for calmly blowing bullshit out of the water. And about 15 minutes into our dialogue, I said this: Listen, we’re not protein-deficient. We’re fibre-deficient. And we’re light-And-timing-deficient. Karan nodded and we went deep into this important topic.
I see that all the time. People are often not aware that it’s not just what you eat, it’s when you eat.
We are not protein-deficient. We’re fibre-deficient. And we’re light-and-timing-deficient.
We know that our body runs on circadian clocks, billions of them across our entire body. And here’s the bit that lit his eyes up. We think of light as something that enters our eyes and gets processed by our brain. But inside your retina are cells which exist purely to tell time (not visual information only). Intrinsically photosensitive retinal ganglion cells (ipRGCs). Cells that don’t project to your visual cortex at all. Instead they align the daily rhythms of every cell in our body, including our gut microbes.
Of course, disrupting light would disrupt your gut! Many everyday human microbes REQUIRE daily cycles of light to reach their full potential. Don’t believe me? Turn down the evening lights and you may be surprised with a higher microbiome diversity… Deepak held up a study from EMBO Reports, a rodent study showing how dim light at night (DIM LIGHT, yep) was enough to alter the daily rhythm of gut microbes (Wu et al., 2018, DOI: 10.15252/embr.20 2052316). Not bright lights. Mouse house lights. That was one of the studies that inspired my own research experiment in Oxford in 2024 where I studied the impact of dimmed light in the evening on our gut microbiome diversity and eating behaviour on the next day. Does it ring a bell? We all have been there, feeling so peckish (on the sugary and fatty food) after a few nights of sleep disruption.
Time for my favourite nonsensical bogeyman: social jetlag. Sleep on Tuesday till 11am. Roll out of bed before your alarm on Saturday. That’s a shift. And if the midpoint of your sleep differs by about 90 minutes on week nights vs your weekends. Congrats. You have social jetlag. A personal timezone change that you impose on yourself WEEKLY.
In the ZOE PREDICT 1 cohort, greater social jetlag was associated with worse overall diet quality, more sugar-sweetened beverages, less fruit and nuts, and specific gut bacteria differed (Bermingham et al., 20 23, DOI: 10.1007/ s00 394-023-03 204-x).
It gets better. When the researchers factored in dietary quality…oops. Diet only explained a small portion of the association. One analysis? Around 9%. Which means…the variance in timing itself explained the rest. Your sleep-wake cycle isn’t just the vessel that carries whatever bedtime snacks and early morning routines you love to hate. It’s a signal. To your genes. Nope. Sleeping in on the weekend will not undo your microbiome.
Please stop sabotaging yourself like that. But getting out of bed at a different time on Sunday vs Tuesday? That throws your microbes off. So does when you expose yourself to your brightest light. Your body likes routines. Regularity. When you go to bed and wake up. And when you get the brightest light of your day. Phones in bed ruin both. See where I’m going with this? Your body loves consistency. Predictability. And that’s how it likes its fibre. Not oat bran sprinkled over low-fat yoghurt. Real food. Plants.
With a fantastic complexity of fibre that your body can’t begin to process without the synergistic chemicals inside each plant cell wall. Matrix matters. Some animals don’t thrive on processed diets for this very reason. And yes, plants have incredible shapes, sizes and colours of fibre that feed different microbes. But as researchers highlighted in this analysis of the American Gut database (McDonald et al., 2018, DOI: 10.1 128/mSystems.00031-18), it’s not just one type of fibre wormies love. In this study, people who ate the most microbiome-friendly plants (defined as >30 different plants per week) had higher species that produce short-chain fatty acids. SCFAs. Bacteria-fuel that your gut lining thrives on. But emerging research suggests they may also be “timing cues” for your liver clocks and others downstream. Except there’s a catch, and where I stop talking with certainty. Almost all the clean mechanistic-data linking SCFAs with peripheral clock genes is from animal studies. And although we have just finished editing our own exhaustive review in Frontiers in Physiology on this topic, we couldn’t find many human intervention studies to include. So take my speculation here as you will in a science podcast. We think it’s probably real. Studies suggest it’s beneficial. We just don’t know how strong it is yet.
No biggie. What is established then? You have three knobs in life that can reset your day-night cycles. None of them requires a prescription. Or even money. Just consciousness.
The time you catch your brightest light. The time you eat your last meal. And how consistent those times are from Monday to Sunday. Go back one week. Move one meal 20 minutes earlier. Wear a sleep tracker on your weekend and make your wake-ups as dull as your Monday mornings. That’s not taking magic pills. That’s helping your body tell time again.
Drop me a line and share with me what time did you see your brightest light today? And when did you finish your last proper meal?
I read every response.
With warm wishes,
Adriano Dos Santos, MSc
The Circadian Nutritionist™