CHICAGO — Jennifer Lopez, Olivia Wilde and other celebs have testified about a banner crop of detox regimens that replace meals for a period of three or more days.

These juice-based concoctions boast vitamins and other nutrients. We figured even the least disciplined among us could handle a gateway cleanse.

So we tested three, consisting of either perishable pre-mixed juices, which are v by FedEx on the day you are to begin, or dried fruit powders that you reconstitute with water or juice and therefore have a longer shelf life.

Here’s a look at three experiences.

Kaeng Raeng All Natural Detox Drink

Level: Beginner

Price: $69.99 excluding tax; kaengraeng.com and in select Whole Foods stores.

Tester: Wendy Donahue

The promise: “Jump-start weight loss, remove toxins, bolster immunity, improve digestion, enhance skin and hair quality, relieve bloating, reduce cravings and overeating.”

The drill: Mix individual powder packet with 24 to 32 ounces of liquid as a meal replacement for three days. Mixing with yogurt, juice or nondairy milk is permitted. Beginners are allowed to snack on raw fruit and vegetables. Green tea is condoned, but not alcohol or caffeine.

Taste: My first was a packet of strawberry-raspberry-pineapple at about 10 a.m. with 24 ounces of water. Hard to dissolve, but I like the chewy-powdery lumps. Not too sweet, not too earthy. It quells hunger and, being a serial snacker/sipper at work, I find it reassuring to reach for it over the course of a couple of hours. The mango-peach-pineapple mixed with water in the afternoon is less appetizing, with a split-pea soup color and wan flavor.

Day 1: Higher frequency of bathroom breaks, but not embarrassingly intense. A few hours after starting the first drink, I’m feeling sleepy, and hunger is setting in, so I mix my second around 3 p.m. No headache has developed (I drank one cup of coffee that morning but usually have two). At 7:30 p.m. I arrive home famished to see a bowl of Quaker rice crisps on the counter. I cave, substituting these crisps for my third drink.

Day 2: Customer support confirms that my choice of alternatives last night wasn’t advisable (particularly because of cheesy coating), but that the cleanse is not ruined. (Try raw cashews next time, I’m told.)

At 10 a.m. I mix the strawberry-raspberry-pineapple again. My energy level and mood remain steady and better than usual throughout the day, and I abstain from the fried calamari being passed around during lunch at a pub. Instead, I order a house salad, no dressing, and savor the flavor and texture of cherry tomatoes and radishes like never before. For dinner, I eat raw cashews at home. Three drinks in a day is just too much for me.

Day 3: I combine the blueberry-blackberry-banana with rice milk and frozen berries in a blender for breakfast, a welcome enhancement from water. Energy, spirits and alertness still high. I haven’t lost true weight; liberal nut intake is probably to blame.

Days 4 and 5: Cleanse over, I treat myself to a Cobb-type salad for dinner; not beyond reproach but superior to many menu options at a restaurant. Two days after cleanse, I bring a whole avocado and nuts and watermelon to work for lunch, which is not like me. I continue to feel more attracted to wholesome foods.

Verdict: Thumbs up, particularly for those soft on self-discipline. The single-serve powder packages are less expensive and more shelf-stable than many other cleanse regimens. I could do a two-a-day like this again to correct a course of excess.

Organic Avenue LOVEdeep

Level: Intermediate

Price: $210; organicavenue .com

Tester: Ross Werland

The promise: “Bright eyes, mental clarity, physical glow, feeling grounded and balanced, clear skin, heightened consciousness, perfect weight, positive thoughts, synergy with people, animals and the environment, a sense of calm, feeling and being more loving, incredible stamina, overall improved physical health.”

The drill: Organic Avenue suggests a cleanse of at least five days; I did three. That meant seven bottles a day of its cold-pressed organic vegetable and fruit juices on a timetable and in prescribed order (one shot-glass size, followed by six 14-ounce bottles). No solid food, coffee, beer or wine; nothing but water between the juices, plus a little hot, caffeine-free tea at night.

Taste: I am disciplined with my mostly Paleo diet, but I found some of the hard-core green juices unpalatable on day one. By the third day it was easier, but I never became a fan. The fruit juices (watermelon, ginger lemonade and pear) were a treat.

Day 1: Not long after taking the first dose, a shot of chlorophyll at about 10 a.m., I made my first bathroom visit. I lost track of bathroom visits on the first day. I do know it was in the teens. Developed a dull headache. I was craving a taste of anything other than the juices, so I cheated with a cup of low-sodium chicken broth at night. I also had a cup of decaffeinated tea.

Day 2: A little easier to take as my palate adjusted slightly to the grassy green drinks in the seven-drink regimen. These green drinks, however, seemed to have the most potent cleansing effect. I cheated with the broth again at night. I also had another tea. Bathroom visits were frequent but reduced from Day 1.

Day 3: I felt like a sports car, with a burst of new energy and a sense of well-being. I also was looking forward to the next day’s cup of coffee. Bathroom visits were almost back to normal. All three days, I never felt hungry. One unexpected change was a dramatically enhanced sense of smell.

Day 4: Cleanse over, I felt supercharged, running for most of what usually is a 1 1/2-mile morning walk. I felt so good, I skipped the morning coffee and waited until noon to have a small cup. One of the reasons I wanted to try this cleanse was because of what I think are undiagnosed symptoms of irritable bowel syndrome. Those were gone, though I don’t know whether to credit caffeine/alcohol cessation or the juice. And my weight was down more than 4 pounds.

Verdict: Thumbs absolutely up! No question that this was good for my body. I find merit in the cleanse itself, which you probably could achieve by fasting with water alone, but the juices you’re consuming are loaded with nutrients, so not only are you purging, but you’re also loading tremendous goodness into your system. Also, you’re not polluting yourself with coffee and alcohol. I’d be interested in post-cleanse maintenance, perhaps one cleanse day a month. I think a juicer might allow a person to replicate the best parts of this regimen.

BluePrint Renovation Cleanse

Level: Beginner

Price: $75; blueprintcleanse .com

Tester: Ellen McGuire

The promise: Detoxify without hunger or overly “grassy” concoctions. Targeted to real people who like a martini and steak but want to lose a few pounds or rebound from an indulgent weekend.

The drill: Six juices per day, in numbered order, for three days. Phasing out sugary and meaty indulgences a few days beforehand is encouraged. Other raw fruits and vegetables (dressed with lemon juice and olive oil) are allowed during the cleanse.

The taste: Surprisingly pleasant. Of the six juices, my favorites were P.A.M. (pineapple, apple, mint), the Spicy Lemonade and the Cashew Milk. The Green Juice and the C.A.B. (carrot, apple, beet) will remind you that, yes, this is a health food cleanse. Final juice of the day, combining cashews, vanilla and cinnamon, was the biggest treat.

Day 1: I enjoyed all of the flavors and felt energized, healthy and full.

Day 2: I felt so invigorated I tried out a new morning yoga class. But by mid-afternoon I was a bit lightheaded and low on energy, though my body felt less bloated and my skin looked smoother.

Day 3: The biggest mental challenge. I was tired of the juice flavors and really missing the fun of eating. However, my energy level rebounded from the day before, and my snug clothes fit more comfortably.

Verdict: Thumbs up! This cleanse has inspired me to continue making healthier food choices.