Metabolism
Fruit and Insulin Resistance
Fruit is often blamed for weight gain and insulin resistance. But the body's energy status is the decisive factor—not carbohydrates alone.
Metabolism
Fruit is often blamed for weight gain and insulin resistance. But the body's energy status is the decisive factor—not carbohydrates alone.
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Sometimes I (Chris) get frustrated with myself for being so curious and always having to read something. Now I accidentally stumbled upon something that we actually didn't want to discuss, but that has gotten under my skin so much that it needs to be revisited. A few days ago, I came across a forum post from my colleague Doc Strunz. You probably know him. In his newsletter, he mentioned "22 secrets"—22 what he calls "gems" that you can pluck, including one point: fruit fasting. "One day per week consisting exclusively of fruit."
This point is met with astonishment by his readers in the corresponding forum thread. The consensus: fruit = sugar = insulin = insulin resistance and weight gain and diabetes – or something like that. How can he recommend something like that? A classic Louis de Funès moment ("No, wait, oh!"). Correspondingly, a forum member (who also reads here, greetings to you!) writes:
"Whoa, fruit contains fructose and glucose in the same proportion! No wonder blood sugar goes up."
Yes, indeed: fruit contains not only the well-known and frequently maligned fructose, but also glucose, and—as correctly stated—usually in the same proportion. But what does that have to do with insulin release? So you Google how many calories an apple contains. A medium-sized apple, according to Google, contains approximately 55 kcal. Okay, okay, let's be fair. Let's add a banana: 150 kcal, so almost caloric intoxication!
If I now eat 10 apples, that would be about 1 kilogram of apples, and I'd be at perhaps 600 calories. Okay, let's add a kilogram of bananas on top of that, and we'd be at roughly 2,000 kcal—a day's worth for a small, delicate woman. But when was the last time you ate 10 apples and a kilogram of bananas (roughly 6-8 large bananas)? What normal body, what normal person eats like that? To cover a day's caloric needs with fruit alone in real life, you'd have to go to great lengths.
But what do calories have to do with insulin? Insulin is not a "carbohydrate hormone" that's only released when you eat a few carbohydrates.
Insulin is like a fuel gauge that tells us very precisely how much energy you already have in the tank. Simple to understand: if you're overweight and have lots of fatty acids in your blood (crucial detail!), you're constantly overloading your cells with energy. You see, right? Energy doesn't disappear; quite the opposite. What you've eaten is swimming in your blood, constantly. What will happen to your insulin, your fuel gauge? Exactly: it will be chronically elevated.
What happens to insulin if we now stuff even more energy into the body? It will rise even further, quite acutely. Right. And what if we don't supply any energy? Then we have a negative energy balance, the body has to tap into stored energy, the tanks begin to (slowly) empty, and as a result, insulin drops directly. Until it reaches a healthy, low level, it will take a few weeks—as long as it takes until the tank isn't overfull anymore. This can be seen very well here.
The ideal scenario: the tank is pretty empty (= blood doesn't constantly have lots of energy swimming around), insulin (the fuel gauge) is low, and cells become insulin-sensitive. Now something wonderful happens in healthy people. Working tissue (like muscle, for example) isn't bombarded with hip-fat fatty acids and, because it needs energy, constantly draws sugar from the bloodstream—completely without insulin. Therefore, acute insulin release is a direct measure of how strongly cells are held in energy deficit (= little insulin needed) or energy surplus (= lots of insulin needed).
So, long story short: if metabolically unhealthy people manage to drive their insulin levels up by eating low-calorie fruits that contain a few carbohydrates ... then they have a big problem. The energy metabolism of a healthy person would only smile tiredly and wonder when real calorie amounts will finally come in. In such people, insulin levels wouldn't rise or would rise only slightly despite the carbohydrates they contain.
➜ We all have the natural problem that when we really focus on something, we often go too deep. You lose perspective and sense of proportion. So we say: sometimes people should just turn off the internet and take some distance. Then they might realize how absurd these discussions—here on the topic of fruit—actually are. The topic of insulin can only be understood if you factor the body's energy status into the equation. Focusing on carbohydrates alone is inadmissible.
We have many articles on insulin and insulin sensitivity on our blog. This one here explains today's topic in detail.
