We cannot simply attribute obesity to gluttony and sloth. Some people really can eat more freely than others. Identical twin adults differ by less than 1 kg in weight, suggesting a genetic element. But genes don’t change in a generation, so what’s going on?
Tim Spector, a professor of genetic epidemiology at King’s College London, studies twins and the microbiology of bowel contents. This book presents his explanation of why people gain weight, fail to lose weight, and why allergy seems to be everywhere. The book is written for an intelligent lay audience, in a conversational style, well peppered with case histories and reports from research papers. Inadequate or maladapted bowel flora contribute to both obesity and allergies. Spector says the problems begin in utero. Avoiding peanuts and unpasteurised cheeses during pregnancy limits the diversity of a mother’s own bowel flora and deprives the fetus of polyphenols (which act as antioxidants, lower lipid levels, and control genes moderating the immune system). A baby born by caesarean section may take over 3 months to develop normal bowel flora and antibiotics given to a mother limit the flora in breast milk. Antibiotics and gastroenteritis purge the gut, impairing digestion, absorption, and sometimes causing inflammation.
After gut purging, what you eat determines how swiftly your gut flora recover. Sugary foods, processed foods, and artificial sweeteners (as bad as sugar) impair the restoration of a healthy microbiome and raise blood sugar and insulin levels.
Spector offers support for the hygiene hypothesis. He recommends that a swab from mum’s perineum should be swept over baby’s face after a caesarean birth. He advocates playing in the dirt, having pets, perfunctory washing of food, following a Mediterranean diet, with garlic and olive oil (polyphenols), a little meat, plenty of fibre, yoghurt with probiotics, and lots of variety. He gives ‘best before’ dates short shrift, both for food and drugs. You might use some of the anecdotes in consultations, recommend the book to some patients, enjoy it yourself, and Spector even offers readers an opportunity to have their bowel flora tested.