First things first: Is juicing going to detoxify your impurities, or nah?
If you drink only fruit juice, you’ll be drinking a LOT of sugar.
And here’s what that might do to your body:
1. In the immediate short-term, your pancreas creates a bit more insulin than it normally does, to help your body manage all that extra sugar.
2. Your blood sugar levels go up a bit higher than they normally do. That’s in part because of the extra sugar, and also because you’re not eating other macronutrients such as fiber and protein that help slow your digestion down and moderate your blood-sugar levels.
3. If you’re the type of person who responds poorly to fluctuations in blood sugar, you’ll potentially experience the jittery highs and miserable lows of sugar highs and crashes…
4. …but you might also not experience any adverse effects, Buse said. Everybody is different, and most people don’t have any major noticeable reactions to eating (or drinking) a lot of sugar.
If you drink only veggie juice, you’re going to be missing out on necessary carbs.
Kale is great for you, but eating exclusively kale (or kale smoothies) can have some downsides. See, your body needs some carbohydrates to function normally. And it’s really hard to get all the carbs you need from veggies alone. And this can have some weird side effects (more on that in a bit).
The lack of sodium could make some people feel lightheaded.
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“When you don’t eat enough salt, people who have a tendency to hypotension [low blood pressure], especially when you get up and sit down … can have a dizzy feeling,” Ravussin said.
And if you’re not eating enough carbs, you might feel a bit…woozy.
When you’re fasting or aren’t eating enough carbohydrates (typically less than 50 grams of carbohydrates a day, and more for people who work out a lot), your body can go into a state called ketosis. That’s essentially when your body creates another form of energy (molecules called ketone bodies) to use as fuel. Your brain normally uses glucose for energy; but in the absence of enough glucose (from fasting, and not eating enough carbs), your brain can use ketones as fuel, too. “Some people when they fast have a sense of feeling drunk or woozy — part of that is from the ketones,” Buse said.
This is why it’s important to drink both fruit and veggies, not just veggies. It’s really hard to get enough carbs from vegetables alone.
The “healthiest” juice cleanses are the ones that combine juices from a variety of sources: fruits, veggies, nuts, and so on.
Oh, and actual whole foods, so you can get some fiber and amino acids and healthy fats in your diet. You know, standard healthy eating.
In all seriousness, just because going on a pure juice cleanse isn’t the healthiest doesn’t mean you should swear off juices or juicing altogether. We’re talking about consuming more fruits and veggies, after all. So supplementing your regular balanced meals and snacks with the occasional vegetable and fruit juice can be a healthy choice. This could potentially be a “sustainable lifestyle change or strategy,” Schilling said.
But if you’re otherwise healthy and you still really, really, really want to go on a juice cleanse…fine. Knock yourself out.
Just limit it to no more than a few days, Ravussin said, so that your short-term nutrient- and calorie-deficits don’t turn into actual health problems. And whatever weight you lose during that time…don’t expect to keep it off for long.