What happens in your body on a cleanse

Adapted from an article by Thorin Klosowski and Beth Skwarecki

Fruit and vegetables are good for us, so that suggests that a diet of just fruit and vegetables must be super healthy. Not really. If you drink only juice for a week, you'll lose weight, because you're not eating, not because your body is detoxing. Water is stored in your muscles with glycogen. When you eat a low calorie diet, you use up those glycogen stores, and lose the water weight with it. You'll gain that water weight right back when your normal diet resumes. You'll also miss out on other vital nutrients like fat, fibre, and protein. In fact, some cleanses suggest avoiding exercise when you're on them because your caloric intake is too low, which leads to fatigue and dizziness.

After a few days, your body is running on fumes, and without protein your body might start to break down muscle tissue instead. Likewise, the lack of fibre in your diet can impact the function of your large intestine, which may be why people describe a juice cleanse as similar to the stomach flu.

The thing is, a juice cleanse doesn't do anything that your body doesn't already do on its own. Our bodies are pretty good at removing toxins. If you needed a yearly detox, we'd all probably be dead.

Will just juice for 3-5 days land you in the hospital or result in irreversible nutrient deficiencies? No, but it is also unnecessary. Our bodies remove toxins daily thanks to the kidneys, lungs, and liver. The whole point of going to the bathroom is to flush out toxins.

While most of these cleanses and detoxes aren't dangerous, they can cause problems. Juices don't include much fibre, so the body absorbs more fructose, which isn't great.

The good news is that it takes months to get any serious vitamin deficiencies. Most cleanses are useless but not seriously harmful, if all you're doing is restricting food for a few days.

As for eliminating toxins, in 15 commercial detox products, none could name toxins, agree on a definition of detox, or supply any evidence for their claims.

All of this is to say: the only thing a detox or juice cleanse actually does to your body is make you hungry and nutrient deprived for a few days. One kind of diet that does show promise however, is the daily intermittent fasting.

It's called “early time-restricted feeding,” where all meals are fit into an early eight hour period of the day (such as 7 am to 3 pm), or spread out over 12 hours (between 7 am and 7 pm). You likely won't lose weight, but after five weeks, you may have dramatically lower insulin levels and significantly improved insulin sensitivity, as well as significantly lower blood pressure. The best part? Significantly decreased appetite. No starving.

Just changing the timing of meals, by eating earlier in the day and extending the overnight fast, significantly benefits metabolism even in people who don't lose a single pound.