Two notes before I begin. First, this is not a diet book or a self-help book. This is a book (primarily) about body science, dealing with the complexities and intricacies that make up the way your body reacts to food, stress, hormones, temperature, exercise, sleep, and about a thousand more things. In places, it reads more like a textbook than anything else. This is not a traditional food/health science book. Second, the book description is a bit misleading. It implies this is a book that teaches you how you can lose weight or gain muscle, neither of which it does. There is a short “recommendations” section at the end, but it doesn’t do any teaching. I’ll discuss that more below.
Okay. So I’ll start by saying that a good chunk of this book was AWESOME. I think body and nutritional science is fascinating. I learned a lot from Gut Reactions. It didn’t oversimplify the science. To give a good example of what I mean, the PDF that came with my audiobook included a handy chart that mapped out how many factors affect each other within your body. It looks like this:
Well, now that’s a good indicator of why it’s difficult to strike the right balance in terms of weight loss and maintenance! Tweak one thing, and a cascade occurs! This is why diet books generally simplify. This mass of information is overwhelming, and the author says it all up front: Every body is different. Every body will react in different ways to different foods, exercise levels, hormones, stimuli, etc. There is no one right way to exist, and each individual has to find what works for them in terms of weight loss. Overwhelming, but at least it’s honest, right? I picked out so many good bits of information. A small sampling:
- Calories in vs calories out is nonsense – or at least, misleading. The actual amount of calories that your body takes in has more to do with your hormones, your body’s homeostasis mechanisms, how fast the food travels through your system, the food’s state (cold vs hot, etc), the kinds of gut bacteria you have and which kinds of food they feast on…etc. So sure, calorie balance is involved, but you can’t just look at the calories in the food prior to eating. So much more is going into play here.
- It takes several months without any sugar before you can retrain your tastebuds to taste natural sweetness in food.
- Fructose molecules (from any source) don’t activate homeostasis mechanisms in the body, and much of it gets processed into fat and stored in the liver.
- There are a lot of vicious cycles in weight – for example, inflammation in the body sets off processes that have a side effect of weight gain, which increases inflammation, increasing weight gain…
- High fat diets can cause insulin resistance even when weight gain and food intake drop. Personal note: This may explain why I became insulin resistant and started gaining weight after eating a higher fat paleo diet for a couple months, even though the fat I ate was the healthy kind and I was at a healthy weight at the time (see photo).
- Wine diversifies gut bacteria, but only when drunk in moderation. In this sense, “moderation” is defined as no more than one drink per week.
- Orexins are hormones associated with better energy balance, increased happiness, better sleep, more energy, and weight loss. So remember back in 2017 when I was searching for why weight loss and happiness always coincided directly for me, beginning and ending at exactly the same time? It’s possible this hormone (or several others similar to it) could be the answer.
- Probiotics in food are mostly killed off before reaching the gut. Probiotics in pill form are designed to reach the gut, but have far fewer strains than you need. Diversity in gut bacteria is more important than the kinds of gut bacteria with regards to health and weight.
So much more than these in this book. There was so much here. Which is why it’s so incredibly frustrating to get to the last little bit of the book. Warning: major rant ahead.
It was right about when we hit the fasting section of the book that it went wrong. First, it began by talking about ludicrously long fasts done under medical supervision in severely obese patients. (Like literally, a guy ate nothing and drank only water for 382 days. Look it up.) Then it casually advocated that any of us who are obese should be able to do something similar for extended periods of time (months!), even if not for over a year. That’s when alarm bells started going off. Um, no – you should NOT starve yourself thin. That’s called anorexia, and any book advocating anorexia under the name “fasting” – without even any recommendation to do it under medical supervision – begins to lose any credit. Especially on the subject of dieting, where body image issues and eating disorders are all too prevalent. You do not suggest not eating at all as a weight loss technique to a population with a high risk of eating disorders!! Also, casually giving verifiably false information (like your body won’t consume its lean mass before it consumes its fat stores) makes the encouragement to do long-term fasting even more unethical.
The book went on to discuss intermittent fasting (different from full fasting above) and all its wonderful health benefits, like losing your insulin resistance. Except studies showing these benefits have only been done on men, and the available information didn’t take female bodies/hormones into account. Fasting is a subject that has been extensively studied in men, but very little data exists on how it affects women. In fact, what little I could find (very few studies, most with sample sizes too small for statistically significant results) suggests that there are no health benefits for women who fast, and often health detriments. This is particularly true for women with insulin resistance and/or hormone disorders, who often have their insulin resistance and hormone balance worsened by fasting. (Given my personal experience and those of all women I know who have tried fasting, this is exactly the case!!) So suddenly, near the end of the book, I discover that Gut Reactions has this very glaring bias that is all too common, and that calls into question all the other science in the book. Maybe all those awesome things I listed above are only true for men.
Also: Polycystic Ovarian Syndrome (PCOS) is not “metabolic syndrome for women.” There are women with metabolic syndrome that don’t have PCOS, and women with PCOS who don’t have metabolic syndrome. Unbelievable.
Then we move on to the “Recommendations” section, which proceeded to give advice that was pointless, asinine, dubious, oversimplified, outdated, condescending, and/or dangerous. Yeah, we all know you’re supposed to eat slower so that you give your body time to realize you’ve eaten enough. And no, it’s not cool to say that when you’re lonely, you should find a friend to talk to instead of talking to Ben and Jerry. I don’t care if it was meant to be a joke. It. Is. Not. Cool. Beyond that, the advice – particularly the oversimplified advice – directly contradicted everything the author said when he discussed how complex this all was. As if all these complicated mechanisms in our bodies, all in delicate balance, will suddenly work right if we follow a couple trite guidelines that most of us already follow (to no avail).
Now couple this with the author treating overweight/obese folks like idiots who don’t realize they’re eating mindlessly and who underestimate their calories by half and who cause their own downfall. Everything about this is not okay! I guarantee that for the most part, overweight and obese people are far more conscious of their situation and habits than people who have never worried about their weight. They’ve tried everything listed under “recommendations” and more, and I’d guess that most have seen little to no results. Hell, that’s why I found this book interesting in the first place – it discusses all the reasons that those traditional recommendations don’t work! Why follow it up with all this useless and insulting advice? It makes me wonder if the publisher said the author couldn’t just write a book about the science and needed to include advice as well. The author is a chemist, not a health science expert or dietitian. He should have stuck to the chemistry.
I’m not usually this caustic in my reviews. The last little bit of this book made me very, very angry. Up until the fasting section, it was an awesome book, and if anyone is looking to read about the science of nutrition, this is a good one. But I highly recommend skipping the rest unless you’ve somehow never heard the advice about using smaller plates or drinking a glass of water when you’re hungry.
A personal pet peeve: Why the hell is an apple always considered the standard marker for determining hunger? If I’m truly hungry, there’s no way in hell that I’ll eat an apple. An apple spikes my blood sugar and makes me ravenously hungry 15 minutes later, and I’ll stay hungry for the rest of the day. The apple also makes me feel sick and gives me a histamine response, like all simple sugars do. If I’m going to eat an apple, I’m going to eat it with some nuts or a piece of cheese. Then it’ll stick in my system for hours and cause no problems. This is how insulin-resistance works. You don’t just eat simple sugars (from fruit or any other source) alone. Statements like “If an apple doesn’t make [someone] happy, they weren’t really hungry” are ridiculous. I call BS.
Performance: Audiobook is read by David Marantz. It was an extremely dry and tedious reading. I wish I’d had access to a physical book.