Your guts are home to a surprisingly huge number of permanent residents – and no, we’re not talking about those marbles you swallowed when you were six that never made their way out the other end. We mean the 4lb of microbes that live mostly in your large intestine, earning their keep by breaking down indigestible fibre into chemicals such as methane and hydrogen sulphide, and synthesising vitamins like B12 and K. But that’s only the half of it; an increasing body of research is revealing the vital role gut microbes play in many other aspects of health, and one of those grabbing the most attention is obesity.
In The Diet Myth, Tim Spector, professor of genetic epidemiology at King’s College London and lead scientist on the British Gut Project, looks at the influence of modern food and lifestyles on these microbes – your microbiome, with which you share 38% of your genes – and, in turn, how this affects health and wellbeing, including the propensity to gain weight.
Obesity is something that has concerned Prof Spector for decades. He recalls how, as a young doctor in the 1980s, ‘I was regularly told by my consultant bosses to tell obese patients with major health problems to exercise, to take control of their lives and use their willpower to stop overeating, or perhaps to remind them that there were no fat people in concentration camps. Needless to say, these not-so-subtle ‘medical’ methods failed miserably. What was needed was a total change of approach.’ Indeed.
One such approach stems from the pioneering work he has been doing since 2011, leading the UK’s largest microbiome project – a huge genetic study into 11,000 adult twins – which has enabled him to examine correlations between bacteria found in their guts and their overall health and propensity to gain weight. This research forms the backbone of his thesis: that modern diets packed with high-sugar, processed foods reduce our microbial diversity, which increases our risk of disease and obesity alike.
Prof Spector explores this idea by examining the latest evidence on the interaction between body, microbiome and the typical components of a food label – from energy and fats, to vitamins and preservatives, as well as antibiotics (which, as he concedes, aren’t on the label but probably should be), including how gut microbes influence our moods by altering levels of the neurotransmitter serotonin. His concomitant demolition of common dietary myths – including the notion that fats are intrinsically bad for us, that breakfast is the most important meal of the day, and the one about exercise being vital for weight loss – is both insightful and engaging.
The takeaway message? For better health, it pays to embrace diversity in your food and therefore in your gut microbes. The book also has details of how to take part in Prof Spector’s British Gut Project – all you have to do is give a shit (quite literally).