If you’ve been following the last few blogs here on sugar, then you now have a pretty good understanding on the negative effects (ie. insulin resistance) as well as how sugar gets stored in your body as fat. In the last blog, we talked about how HIT exercise can help mitigate the negative forces of eating sugar. If we use the analogy that your bathtub filled with water is your body’s fat stores, then HIT is unplugging the bathtub plug to let the water drain out. Eating a low-sugar diet is turning off the water faucet. Combined together, is a good strategy for losing fat.
But what about eating fruit? Fruit has fructose in it – does that mean all fruits are bad now?
Fruit does contain fructose which is very bad for your liver if consumed in high amounts and in a short amount of time as explained in the previous blogs but fruit has one important substance that makes it different from candy.
Fibre is indigestible plant material that makes it tough to chew fruits and vegetables. It’s the stringy bits that gets stuck in your teeth and you just either spit it out or swallow it whole.
I’ll get to why fibre is so important later, but fibre actually consists of 2 different parts: soluble fibre, and insoluble fibre.
Soluble fibre is already dissolved in water. It’s what you mix in water and drink when you are constipated. In food, it forms a gelatinous substance as it absorbs water in your stomach and enlarges which slows down the emptying of your stomach and making you feel full longer.
Insoluble fibre is the former stuff I talked about; the tough and stringy parts of fruits and vegetables. Like the long stringy strands in celery, the skins on grapes. Because it is indigestible, it travels quickly through your small intestines triggering PYY3-36 to tell your brain you’ve had enough to eat. It ends up in your bowels fairly intact and forms the bulk of your stool.
Ok, so far so good – now here’s the kicker.
When the two work together, as they normally do when you eat them as food and not as a supplement, you get a latticework from your insoluble fibre and then the soluble fibre forms a gel-like substance on it which creates a barrier.
A barrier for what?
That’s why it’s ok to eat fruit! Because the fructose contained in the fruit also contains the protective barrier so the fructose doesn’t get absorbed – or at least not so quickly so your liver has a chance to process the fructose and burn some of it off in the Krebs Cycle instead of shunting it to fat.
Quoting from Dr. Robert Lustig:
“When god made the poison, he packaged it with the antidote.”
Unfortunately, when you juice fruit or blend it, the insoluble fibre is destroyed. The insoluble fibre is pulverized into such small particles that the soluble fibre cannot form a barrier on to – the latticework is destroyed. This is when the fructose in fruit juices and smoothies can cause more harm than good. Fructose in its liquid form hits the liver harder than its solid form forcing it to deal with a large load of fructose in a very short amount of time. And as explained in the fructose blog, the liver has no choice but to shunt it to fat cells with lots of inflammation as collateral damage.
Not only that, you normally juice 6-8 oranges to make one glass of orange juice. So you’ve just consumed 6-8 oranges of fructose in the span of 2 minutes. Your liver now has to deal with that amount of fructose all at once. But no one eats 6-8 oranges in one sitting. Normally, we would eat 1, 2 max – and with that, all the nutritious fibre to slow down the absorption of the fructose in the liver.
Juicing and eating fruit is a huge difference of scenarios.
It is true that fruits contain lots of vitamins and minerals, but you must eat the fruit in its entirety, including the skins and the more unpleasant bits to make the whole experience of eating fruit a healthy one.
- Lustig, R. (2013), Fat Chance, London: Fourth Estate.