The Master Cleanse is a liquid-only fast where you consume nothing but a homemade lemonade drink, typically for 10 days. Created by Stanley Burroughs in the 1940s and popularized by Peter Glickman’s 2004 book, it promises detoxification and rapid weight loss. It contains no solid food, no protein, and virtually no nutrients beyond simple sugars and vitamin C. Most of the weight people lose on it is water, not fat, and it comes back once normal eating resumes.
What You Actually Drink
Each serving of the Master Cleanse lemonade calls for 2 tablespoons of freshly squeezed lemon or lime juice, 2 tablespoons of organic grade B maple syrup, a tenth of a teaspoon of cayenne pepper, and 8 ounces of room-temperature or cold water. You drink 6 to 12 glasses of this mixture per day, and nothing else besides water. That works out to roughly 600 to 1,200 calories daily, almost entirely from the sugar in maple syrup.
The cayenne pepper is said to boost metabolism, though any effect is negligible at such tiny doses. The lemon juice provides some vitamin C but little else. There is zero protein, zero fat, no fiber, and no meaningful amounts of vitamins or minerals beyond what the maple syrup and lemon contribute.
The Full Daily Routine
The cleanse involves more than just the lemonade. Each morning, before drinking anything else, you’re instructed to do a “salt water flush”: dissolve two teaspoons of non-iodized sea salt in a quart of warm water and drink it as quickly as possible on an empty stomach. This acts as a strong laxative, typically producing multiple bowel movements within an hour or two. In the evening, you drink a cup of herbal laxative tea, usually a senna-based blend.
Between the salt water flush, the laxative tea, and the liquid-only diet, the cleanse keeps your digestive system almost constantly emptying. Proponents frame this as “releasing toxins.” In reality, it’s a combination of water and electrolytes leaving your body, which accounts for much of the dramatic weight loss people see on the scale during the first few days.
The Three Phases
The full protocol has three stages. The “Ease-In” phase lasts three days before the cleanse begins: on day one you eat only “living foods” like raw fruits and vegetables, day two you switch to soups and juices, and day three you drink only orange juice. Then comes the cleanse itself, lasting anywhere from 10 to 40 days depending on whose advice you follow. Finally, the “Ease-Out” phase reverses the process over three days: orange juice first, then soups and broths, then whole foods.
The gradual reintroduction matters because after days or weeks without solid food, eating a normal meal can cause severe cramping, nausea, and diarrhea. Your digestive system essentially needs to restart.
Why the “Detox” Claim Doesn’t Hold Up
The central promise of the Master Cleanse is that it flushes accumulated toxins from your body. Proponents claim these toxins are responsible for fatigue, joint pain, bloating, headaches, and depression, and that eliminating them restores energy and relieves chronic conditions like arthritis.
Your body already has a detoxification system, and it works around the clock without any special diet. Your liver breaks down harmful substances, your kidneys filter your blood, your lungs expel waste gases, and your colon eliminates solid waste. These organs don’t need a lemonade fast to function. As Harvard Health has noted, before the recent wellness craze, “detox” referred to a medical procedure for dangerous levels of alcohol, drugs, or poisons. There is no medical evidence supporting cleansing procedures like the Master Cleanse as a whole.
The “toxins” the cleanse claims to remove are never specifically identified, which makes the claim impossible to test or verify. No study has demonstrated that the Master Cleanse removes any specific substance from the body that the liver and kidneys weren’t already handling.
What Happens to Your Body
Because the cleanse provides fewer than 500 calories per day for most people (depending on how many glasses they drink), it qualifies as a very low-calorie diet. The effects are well documented. Within the first day or two, your body burns through its stored carbohydrates (glycogen), and each gram of glycogen holds about 3 grams of water. This is why people can lose 5 or more pounds in the first few days. It’s almost entirely water.
After glycogen runs out, your body starts breaking down both fat and muscle for energy. Without any protein intake, there’s nothing to slow muscle loss. Research on very low-calorie diets shows they can lead to vitamin and mineral loss, headaches, dizziness, fatigue, muscular weakness, gastrointestinal problems, and nausea. Restricting carbohydrates to the degree the Master Cleanse does can also cause electrolyte loss, low blood pressure when standing, bad breath from ketosis, and elevated uric acid levels.
The daily salt water flush adds another layer of risk. Rapidly consuming that much sodium on an empty stomach can cause bloating, cramping, and dehydration. Combined with the senna laxative tea, you’re losing fluids and electrolytes from both ends of the process. Electrolyte imbalances can cause muscle cramps, irregular heartbeat, and in severe cases, dangerous cardiac events.
Weight Loss That Doesn’t Last
People typically lose significant weight on the Master Cleanse, sometimes 10 to 20 pounds over 10 days. This sounds dramatic, but the composition of that weight loss tells the real story. The majority is water that returns as soon as you eat carbohydrates again and your body replenishes its glycogen stores. Some is muscle tissue that your body broke down for fuel. A smaller portion is actual fat.
The muscle loss is particularly counterproductive if your goal is long-term weight management. Muscle tissue burns more calories at rest than fat does, so losing muscle lowers your resting metabolic rate. This means after the cleanse, your body needs fewer calories than it did before, making it easier to regain weight and harder to lose it next time. This is the cycle that makes crash diets self-defeating.
Who Should Avoid It
The Master Cleanse is risky for anyone, but certain groups face heightened danger. People with diabetes risk dangerous blood sugar swings from the combination of near-starvation and high sugar intake from maple syrup. Those with kidney disease may not tolerate the sodium load from the salt water flush or the electrolyte shifts. Pregnant or breastfeeding women need consistent nutrient intake that the cleanse cannot provide. Anyone taking medications that require food for proper absorption, or drugs affected by dramatic changes in fluid and electrolyte balance, could face serious complications.
People with a history of eating disorders are also at particular risk, since the cleanse normalizes extreme food restriction and frames it as healthy. The rigid rules, the emphasis on “pushing through” hunger and discomfort, and the focus on rapid weight loss mirror disordered eating patterns.