So many diet books, and so many of them claiming that they are not really diet books. Gene Eating by Giles Yeo is not just an ordinary diet book that claims it is not one. It provides insight into why eating and diets are as much about our genes as they are about the food that we eat. Along the way Yeo debunks much about what modern diet books mislead or misunderstand about food and dieting. It is a refreshing diversion from the many books out there on the topic.

“‘clean’ and ‘real’ have over the past few years have morphed into meaning ‘food is medicine’ and under this umbrella now includes a number of strains of diets, some more wacky than others, but all based on the foundation of pseudoscience.” (pp xiii-xiv) Clean labels and real foods have been discussed on this blog previously. The battle lines around food seem to be drawn between the ‘Food-is-medicine’ and ‘The-dose-makes-the-poison’ memes. So-called superfoods are based on pseudoscience and will not guarantee health. Occasional consumption of ‘unhealthy’ foods will not condemn us to disease and death. Balanced diets promote good health, but they are not treatments for disease. A switch from an unhealthy diet to a healthy one may mitigate symptoms, but it is not a cure. I firmly reject the concept that food is medicine and rely on real medicine when I need to treat a real disease.

“there is a healthy and a toxic dose for most foods. Remember ‘only the dose makes the poison’.” (p228) Unlike those who subscribe to the food-is-medicine concept, chemists and toxicologists embrace the dose-response perspective. All food is made up of chemicals—usually a wide range of compounds with less-than-desirable names. It is better if we work on understanding which foods are safe at the levels they are normally consumed. Not all ‘natural’ foods are safe. Even superfoods can be dangerous if consumed to excess. The discussion in Gene Eating on this topic revolves around cleanse and detox diets which are big these days but are grounded on a pseudoscience foundation. This idea also has relevance in the whole ultra-processed food debate which is really aimed at food additives and not at processing per se.

 “the easy availability of cheap, highly processed food that tends to be lower in protein content is clearly a part of a vicious cycle driving the obesity epidemic, and also exacerbating social inequality.” (p118) Just when I was buying into Yeo’s philosophy, he starts pushing the protein-leverage theory. In other words, protein good—carbohydrate and fat bad. The protein-leverage theory is based on the concept that the body has to expend more energy to break down protein into energy, and thus a protein calorie is not as big a contributor to weight gain as carbs and fats. It is a hallmark of low-carb diets.

Excess consumption of any food can contribute to weight gain. A high-protein diet is by definition an unbalanced diet. A well-balanced diet, however, provides calories for weight maintenance while leaving essential amino acids for more important functions. I firmly believe that the lack of access to affordable food to people who live in food deserts and the lack of home infrastructure to adequately prepare well-balanced meals are much greater factors in American health than low-protein diets.

“The whole idea that most doctors, nurses, scientists and other health professionals today are ‘in the pocket of big pharma’ and want to see the people remain unhealthy at the expense of pushing pills is, to be frank, ludicrous.” (p135) If medicine, food additives and processed food are as bad as we are told, then we are victims of a mass conspiracy between industry and government. Now, I realize that there is some fraud in commercial enterprise and that there is some corruption in government. I firmly believe that most companies are honest and attempt to provide products to us for a profit and that most governmental agencies are dedicated to protect our health, wellbeing and freedom of choice. It is such conspiracies that we are buying when we push up against mainstream science. There can be honest disagreements between different branches of science based on different interpretations of the data, but we need to be careful of smear campaigns based on emotion and not on science.

“the complex interactions between our genes and the environment mean that we all behave differently towards food, and hence there are no easy ‘one-size-fits-all’ solutions.” (pp272-273) But so much of the dietary advice we hear today advocate a ‘one-size-fits-all’ solution. We don’t like uncertainty so we embrace the merchants of certainty rather than more nuanced approaches. Too many of these solutions completely ignore genetics as well as ignoring the importance of caloric consumption and energy balance. Yeo likens genetics to being dealt a good or bad hand in poker. Obesity is a very complex topic that should not be reduced to oversimplistic nostrums.

“Yes, your genes do set limits on what is possible, but for the most part they are not ‘deterministic’; rather, your genes give a range of possible outcomes, depending on how they interact with the environment.” (p 323) In other words, genes matter and much more than most dietary advisors suggest, but they are not the only factor. Neither is the food we eat the only factor in weight gain or loss. The author emphasizes the importance of balance and individual differences. Frequently in research studies it is not the main effects that are nearly as interesting or meaningful as the interaction effects. Unfortunately, too many internet stories focus on main effects rather than their interactions.

Bottom line. There is much to like in this book as it digs deeper than most into the myths behind the pseudoscience associated with much of today’s popular dietary advice. When it comes to obesity, genes matter. Throughout the book, Yeo argues that calories and energy balance also matter. Where we diverge is his embrace of the protein-leverage theory over a balanced diet.