Dr. Emily Leeming: The Chef Who Became a Microbiome Scientist
Chef first, then dietitian, then microbiome scientist at King’s. The order is unusual, and it explains why her writing never skips the part where somebody actually has to cook the food.
Dr. Emily Leeming, PhD, RD is a British microbiome scientist and registered dietitian, and a research fellow at King’s College London, where she studies how diet shapes the gut microbiome. She trained first as a chef, then took a nutrition degree, a master’s in nutrition and dietetics and a PhD in diet and the gut microbiome. She wrote Genius Gut (Penguin, 2024) and Fibre Power (2026), and writes the Second Brain newsletter. She is a dietitian and PhD scientist, not a medical doctor.
The useful thing about a scientist who used to cook professionally is that they already know the part most nutrition advice skips: that food has to be made by somebody, in a kitchen, on a weeknight, and that a recommendation which ignores this is not really a recommendation.
Dr. Emily Leeming trained as a chef before she trained as anything else. She then took a nutrition degree, a master’s in dietetics, and a PhD in diet and the gut microbiome, and ended up a research fellow at King’s College London — which is, at the moment, roughly the centre of the world for this particular science. The route is unusual enough to be worth stating plainly: kitchen, clinic, laboratory, in that order.
The day jobA lab, a cohort and a cancer challenge
At King’s, Leeming’s research concerns how what people eat shapes the gut microbiome, and what that in turn does further upstream. Much of the work sits alongside TwinsUK, the long-running British twin registry that has become one of the more valuable datasets in microbiome research — because identical twins let you separate what your genes are doing from what your diet is doing, which is otherwise close to impossible.
She is also part of the PROSPECT team within the Cancer Grand Challenges programme, a Harvard-led international effort investigating the role of diet and the gut microbiome in early-onset colorectal cancer. That is one of the genuinely urgent open questions in the field: colorectal cancer is rising in people under fifty, nobody yet knows why, and diet and the microbiome are among the leading suspects rather than established causes. It is a research question, not a finding, and worth reading as such.
Chef, then dietitian, then microbiome scientist. The order explains most of what is distinctive about how she writes.
The bookThe second brain, taken literally
Genius Gut: The Life-Changing Science of Eating for Your Second Brain was published by Penguin in 2024 and landed on the Daily Mail’s top reads and Cosmopolitan’s best health books of that year. Its subject is the gut–brain axis — the traffic between the enteric nervous system and the head, and what the microbes in between appear to have to do with mood, appetite and thinking.
It is a subject that attracts a lot of overclaiming, and the book’s better quality is how carefully it distinguishes between what is established, what is emerging and what is still a hypothesis with good press. A follow-up, Fibre Power, was published in May 2026, on the least fashionable nutrient in the shop and the one with the most consistent evidence behind it. She has given a TEDx talk on the same subject, which tells you something about the level of commitment to fibre as a topic.
The newsletterWhere the research actually lands
Second Brain, her weekly newsletter, has passed 40,000 readers and does the thing academic work almost never does on its own: takes a week’s worth of new papers and says, in plain sentences, whether they mean anything for the person reading. She also writes regularly for the Daily Mail and turns up on BBC Radio, in The Sunday Times, The Telegraph and Vogue.
View this post on Instagram
The pattern across all of it is a reluctance to oversell. A working scientist writing for the public has an obvious temptation — every study is a breakthrough, every mechanism is a life hack — and the absence of that register is the most consistent feature of her writing.
What she is not sellingA conspicuously short list
The commercial side is short. Leeming has two books, a paid newsletter tier, and a speaking career, which is a modest list by the standards of this beat. There is no supplement range, no testing kit and no branded protocol, and the advice she gives most often — more plants, more fibre, more variety, fermented foods, and a healthy scepticism about anything sold as a shortcut — costs nothing and belongs to nobody. She is a dietitian and a PhD scientist rather than a medical doctor, a distinction she makes herself.
What makes Leeming worth following is the discipline of the sourcing. She is doing the research, reading the research, and writing about the research for people who will never read a paper — and the through-line is that the honest answer is often “we do not know yet,” which is a difficult thing to build an audience on and a good reason to trust the answers that are not that. If something about your digestion is new, persistent or worrying, it belongs in front of your own doctor. This article is educational, not medical advice.