The Master Cleanse claims to be a way to cleanse the body of and remove the cravings associated with drugs, alcohol, tobacco, eating, "coffee, tea, and various hot drinks." The cleanse involves drinking only a concoction made from fresh lemons, grade B maple syrup and cayenne pepper. No solid food is eaten for the entire cleanse. According to Burroughs, the diet should be followed for a minimum of 10 days and up to 40 days.

Stanley Burroughs and other authors allege that The Master Cleanse will eliminate toxins and congestion that have built up in the body. Proponents of the Master Cleanse have credited it with helping them lose weight, increase energy, and even alleviate some chronic diseases and increase sexual stamina, but there is no scientific evidence that it achieves anything other than weight loss through a low-calorie diet.

For people in good health, the body is designed to eliminate normal everyday toxins from itself through the lungs, kidneys, liver, and other eliminator organs. Nutritionist Jane Clark points to a lack of essential nutrients in this program, citing a deficiency of protein, vitamins, and minerals in the regimen. As a result of these deficiencies, including far fewer calories than the recommended amount for health and optimum functioning, individuals on the diet may experience headaches and a variety of other symptoms in the short term and the diet is potentially harmful over the long term.

Proponents of the cleanse do not recommend it solely for weight loss, instead mentioning its purported detoxifying properties. However because it is dangerously low in calories, if it is followed as described people will certainly lose weight. The program has been described as an extreme fad or crash diet, and any weight lost during the fast can be expected to be regained once the diet is stopped.