I recently wrote a couple of posts explaining that over the years, I’ve revised my explanation of “the alternative hypothesis” from this:
More Carbohydrates => Higher Insulin => Fat Storage
Damaging Diet => Hormonal Disruption => Fat Storage
It’s not the biologically beneficial rise in insulin after a meal that makes people obese, I said in those posts. It’s chronically high insulin (along with other hormonal disruptions) resulting from a bad diet.
In comments, a few of you suggested I read Dr. Jason Fung’s book The Obesity Code because it expresses similar ideas. Good suggestion. It’s an enlightening and very readable book – meaning it passes my “Aunt Martha” test. Your Aunt Martha could read this book without giving up because she doesn’t want to keep a medical dictionary on her desk.
As I expected, insulin is still front and center in Fung’s explanation of why we get fat. In fact, the book’s cover includes the subhead Why your body’s own insulin is the key to controlling your weight. After citing plenty of research to effectively dismiss the “it’s all about consuming too many calories” explanation of obesity in the early chapters, Fung begins chapter seven like this:
I can make you fat. Actually I can make anyone fat. How? By prescribing insulin. It won’t matter that you have willpower, or that you exercise. It won’t matter what you choose to eat. It’s simply a matter of enough insulin and enough time.
Wait … hasn’t Dr. Fung read on the internet that we mustn’t blame insulin because it’s actually a wunnerful, wunnerful appetite suppressant? Well, perhaps he has … but if so, I’m sure he laughed. He has years of clinical experience with the stuff, as he explains in the book’s introduction:
I’ve often watched patients start insulin treatment for their diabetes, knowing that most will gain weight. “Doctor,” they say, “you’ve always told me to lose weight. But the insulin you gave me makes me gain so much weight. How is this helpful?”
… Like many doctors, I believed that weight gain was caloric imbalance – eating too much and moving too little. But if that were so, why did the medication I prescribed – insulin – cause such relentless weight gain?
Fung answers his own question in chapter seven:
Everything about human metabolism, including the body set weight, is hormonally regulated. A critical physiological variable such as body fatness is not left up the vagaries of daily caloric intake and exercise. Instead, hormones precisely and tightly regulate body fat. We don’t consciously control our body weight any more than we control our heart rates, our basal metabolic rates, our body temperatures or our breathing.
But it isn’t just about insulin. Fung includes chapters on cortisol (which triggers weight gain partly by raising insulin) and other hormones, such as leptin, that are involved in weight regulation.
And insulin isn’t just about how many grams of carbohydrate we consume. As Fung writes in chapter nine:
The carbohydrate-insulin hypothesis, the idea that carbohydrates cause weight gain because of insulin secretion, was not exactly wrong. Carbohydrate-rich foods certainly do increase insulin levels to a greater extent than the other macronutrients. High insulin certainly does lead to obesity.
However, the hypothesis stands incomplete. There are many problems, with the paradox of the Asian rice eater being the most obvious.
… Indeed, many primitive societies that ate mostly carbohydrates have low obesity rates. In 1989, Dr. Staffan Lindeberg studied the residents of Kitava, one of the Trobriand Isands in Papua New Guinea’s archipelago – one of the last places on Earth where people ate a largely traditional diet. Starchy vegetables, including yam, sweet potato, taro and cassava, made up the basis of their diet.
It isn’t foods that raise insulin that make us fat, Fung explains in the following chapters. It’s foods that lead to insulin resistance. Once we become insulin resistant, the entire hormonal system goes out of whack. Fung spends the next few chapters describing the foods that likely make us insulin resistant (sugar being a primary culprit) and how insulin resistance makes us fat.
Insulin resistance is largely about what we eat. But rolling back the effects – and perhaps preventing insulin resistance in the first place – is also about when we eat. That was the most useful message in the book for me, since I’ve already read rather a lot about the effects of foods.
As Fung explains, insulin is supposed to rise after meals. But then it’s supposed to drop and stay low for several hours. Back when few Americans were overweight, that’s what happened — because we ate three meals per day, period. Now we add constant snacking into the mix. When I was shooting interviews for Fat Head, Dr. Eric Oliver, author of Fat Politics, said that while people like Morgan Spurlock want to blame obesity on restaurants for serving larger meals, the real problem seems to be how often we eat between meals. Fung explains why that’s such a problem:
The balance between the fed state (insulin dominant) and the fasted state (insulin deficient) has been completely destroyed. We are now spending most of our time in the fed state.
… We are taught to eat the moment we roll out of bed. We are taught to eat throughout the day and again just before we sleep. We spend up to 18 hours in the insulin-dominant state, with only six hours insulin-deficient.
A lousy diet, of course, makes snacking irresistible. Refined carbs jack up your blood sugar, and your body responds by flooding your bloodstream with enough insulin to give you low blood sugar. If you work in an office, I’m sure you’ve seen exactly what Fung is describing. I see people eat their white-bread sandwiches at noon, and by 3:30 they’re back in the cafeteria, trying to decide if they should raise blood sugar with a candy bar, a bag of chips, or some microwaved popcorn.
Fung describes this as the vicious cycle that leads to insulin resistance. When insulin is too high, too often, cells down-regulate their insulin receptors. Then the body cranks out more insulin to try to lower high blood sugar. Then we get fatter. And hungrier. And snack more often.
Part of the cure is real food, and Fung devotes a good chunk of the book to the topic. But another part of the cure is to dial back insulin resistance through intermittent fasting. As you know, I’m a fan of the Wisdom of Crowds. Fung reminds the reader that in nearly all ancient cultures, periodic fasting was considered a boon to good health. It was part of their wisdom.
In the final chapter, Fung lays out the why and the how of intermittent fasting. Here’s part of the why:
To break the insulin-resistance cycle, we must have recurrent periods of very low insulin levels. But how can we induce our body into a temporary state of very low insulin levels?
We know that eating the proper foods prevents high levels, but it won’t do much to lower them. Some foods are better than others; nonetheless, all foods increase insulin production. If all foods raise insulin, then the only way for us to lower it is to completely abstain from food. The answer we are looking for is, in a word, fasting.
In the rest of chapter, Fung describes the hormonal effects of fasting and dispels the many myths about going without food … such as “it will depress your metabolism.” Interestingly, the research he cites here and in other chapters shows that while living on a low-calorie, low-fat diet will indeed slow down your metabolism, periodic fasting doesn’t. Apparently we’re built for it. Given that paleo man’s hunts weren’t already successful, that makes sense.
Jimmy Moore and Dr. Fung are co-authoring a book titled Fasting Clarity that’s scheduled to be published later this year. I’m looking forward to reading the expanded version of this topic.