The internet is littered with commentaries about the supposed benefits of doing cleanses and detoxes. It’s understandable that people are uncertain about how to proceed.
The first thing you should understand is that cleanses and detoxes are different things. Cleanses usually focus on the elimination systems of the body, and detoxes are intended to promote elimination of specific substances. There are some medically justified reasons for using one or the other. For example, a cleanse might be required prior to a bowel procedure, such as a colonscopy. A clinical detoxification procedure might be required because of drug or alcohol abuse, or exposure to an environmental contaminant. Some people also use the term cleanse or detox when they are actually referring to a fast, such as a juice fast. A fast occurs when you restrict your diet dramatically, by excluding everything but juice or water, as examples. There are various types of fasts that can last for different amounts of time.
The second thing you should understand is that your body has amazing mechanisms for detoxification that are built into its everyday functions. These include processes you would expect, such as urination and defecation, but also some you might not think of, such as respiration and sweating. You can support your body’s processes by
- drinking lots of water,
- eating a clean diet that provides lots of fiber,
- doing deep breathing exercises and/or working out,
- using a loofa or a scrub brush to exfoliate your skin and improve the circulation to it.
I often get asked about cleanse and detox products that are available for do-it-yourself use, and whether these should be periodically applied, or if they are of benefit prior to starting a diet, and so on. Despite the proliferation of products aimed at cleansing and detoxifying, the scientific support for these is lacking. In fact, there isn’t even good evidence that these products do what they claim.  
Doing a cleanse or detox before beginning a new kind of diet is unnecessary. But what about the results people claim for detox diets and cleanses? Some of these are real. Because detox diets are so limited, weight loss or fluid loss will occur rapidly. This does not mean you are detoxing. It means you are experiencing weight changes due to caloric restriction and, usually, a lower salt intake.
If you are considering a cleanse or detox as an antidote to a period of indulgence, stop. If you are healthy, your body can handle an occasional indulgence. If you want to get healthy, your best bet is to use the boring approach of moderation: eat a clean diet and support your body’s processes of elimination as outlined above AND make these long term parts of your lifestyle.
You can also focus on ensuring your gut is populated with helpful probiotic bacteria. Probiotic bacteria work with bodily processes and dietary factors to influence how protective mechanisms in tissues along with those initiated by the immune system keep us healthy. When the digestive tract has healthy microflora, it functions more effectively, and this includes the way it expels toxic substances from the body. 
Detoxes and cleanses that are not being recommended or administered in a clinical setting by an MD or ND are generally useless and occasionally harmful. The kinds of cleanses sold at health food stores or promoted for do-it-yourselfers online can be damaging to the microbiota in your gut. Eating ice cream infused with activated charcoal will not make you healthier. The Master Cleanse doesn’t actually cleanse anything.
Anyone who is serious about wanting good health should approach interventions as parts of a long-term, lifestyle based strategy. Cleanse and detox products won’t get you where you want to go in terms of ongoing health and could be harmful, so unless your doctor advises otherwise, skip the products.