A disclosure before we go further: I develop soup cleanse products, which is a reason to read the evidence sections closely rather than take my word for it. Where the research is thin, I’ve said so.
Texture settles nothing
Both plans pass the straw test. A juice goes through a straw, and so does a blended soup. From across a table the two can look like the same idea in different glasses. The difference is in what each liquid still contains.
Fiber
Juicing separates the liquid from the pulp, and the pulp holds most of the fiber. A blended soup keeps all of it, since nothing gets strained out. That one difference drives most of the others. Fiber slows how quickly sugar enters the blood, it feeds the bacteria in your colon, and it gives a liquid enough body that most people find it more filling than a thin juice.
Sugar
The World Health Organization counts the sugar in fruit juice as free sugar, the same category as the sugar in honey and syrups. Its guideline recommends keeping free sugars under 10% of daily energy, which is roughly 50 grams for an average adult. The sugars held inside intact fruits and vegetables are left out of that guideline.
How far that applies to a given juice cleanse depends on the recipe. Green-heavy juices carry less sugar than fruit-forward ones. A soup built on vegetables and legumes starts with far less sugar than a fruit juice does, and its fiber arrives together with whatever sugar it has.
Protein, fat, and salt
Fruit and vegetable juice contains very little protein and almost no fat. A soup built on legumes and a little oil carries both. The muscle post follows that thread through three days.
Salt is the other gap. Most juices contain very little sodium, and a juice plan has no natural place to put it back. A soup cleanse adds salt to every batch on purpose, because low sodium piles onto caffeine withdrawal in the day-two headache.
What the studies found
The research on juice cleanses is thin, and the best-known studies are small. In a 2017 study from UCLA, published in Scientific Reports, twenty healthy adults drank six bottles of juice a day for three days. They lost about 1.7 kilograms, or 3.7 pounds, and the makeup of their gut bacteria shifted, with part of the shift reversing over the next two weeks. The authors tied the changes to the weight loss and to a few blood and urine markers. The study followed people for only 17 days, so it can’t say whether the bacterial changes lasted or helped anyone.
A 2025 study from Northwestern, published in Nutrients, put fourteen people on one of three diets for three days: juice only, juice plus regular food, or whole plant foods. The juice-only and whole-food diets were both set at 800 to 900 calories, so the comparison held energy steady and left the form of the food as the variable. Gut bacteria changed little overall. The juice-only group showed increases in some bacteria linked to inflammation and gut permeability, and the mouth changed more than the gut did. With four or five people in each group, larger studies are needed to confirm any of it.
The two studies framed their findings differently, and with groups this small neither can carry much weight. The Northwestern design is the closest anyone has come to this comparison, and its whole-food arm, the one that kept the fiber, showed the mildest changes. I haven’t found a trial of a soup cleanse itself, so the case for keeping fiber in the pot comes from studies like these and from what fiber is known to do.
What neither plan does
A 2015 review of detox diets in the Journal of Human Nutrition and Dietetics found very little clinical evidence behind them and noted that no randomized controlled trials of commercial detox diets in humans had been done. That finding covers soup cleanses as much as juice cleanses. Your liver and kidneys do the removing, every day, without a plan to help them, a point the myths post takes further.
What either plan can offer is a few days of changed eating. The weight that comes off is mostly water, and it returns within days.
A rare kidney problem
Case reports in kidney journals describe acute kidney injury in people who juiced or blended large amounts of raw spinach and other high-oxalate greens. A 2017 case in the American Journal of Kidney Diseases involved a 65-year-old woman on a green juice cleanse who had earlier had gastric bypass surgery and had recently finished a long course of antibiotics. Her kidney function went from normal to end-stage disease. Other reports involve diabetes, dehydration, or existing kidney disease.
These cases are rare, and they come from large daily doses of raw greens, which a blended drink can deliver as readily as a juice. Kidney disease is already on the list of reasons to skip a cleanse. Anyone with a history of kidney stones should ask a doctor before building any plan around large amounts of raw spinach or chard.
Where juice has the edge
Juice needs no cooking and travels well. It’s cold and sweet, which some people want at three in the afternoon, and a juice plan asks less of your kitchen. A soup cleanse needs a blender and an evening of prep, and that is the main cost of the plan.
If you like juice, the Northwestern authors’ own suggestion was to blend it so the fiber stays in, or to drink it alongside whole foods. If you’ve done a juice cleanse and want to compare, the 3-day guide has the shopping list and the daily framework.
Common questions
- Is a soup cleanse better than a juice cleanse?
- They keep different things. A soup cleanse keeps the fiber, protein, and salt that juicing removes, and a juice cleanse is cold, sweet, and needs no cooking. Neither has been shown to detox the body.
- Does a soup cleanse have more protein than a juice cleanse?
- Yes, when it’s built on legumes. Most fruit and vegetable juice contains very little protein.
- Does a juice cleanse detox the body?
- A 2015 review found very little clinical evidence that detox diets work, and no randomized trials of commercial ones in humans. The liver and kidneys remove waste continuously.