Fasts and cleanses have been around for a while. The question is “Do they work?” The answer depends on your reasons for doing the fast or cleanse. Many people think cleanses will remove “toxins” from their body, promote healing, or cause weight loss. Regardless of the type of cleanse or fast you’re considering (soup, juice, water, etc.), consider the following:
The “cleansing” effect
As long as you’re healthy, your organs and internal systems should be purging “toxic” or unhealthy substances from your body (as suggested here). Rather than relying on periodic cleanses to purify your body, why not just follow healthy practices in the first place? True, your body may have accumulated toxins over time. Cleaning up your diet and lifestyle can help cleanse and prevent further accumulation. Also, the benefits of cleanses are questionable, as the NIH stated and other studies. Attributing causation could be difficult. For instance, you might feel better after a cleanse because you eliminated unhealthy substances and excess calories during that period.
You can lose weight during a cleanse, but for reasons other than what you’re consuming. Most people consume far fewer calories than normal. Thus, the cleanse essentially serves as calorie control, which will naturally result in weight loss. Also, liquid or low-sodium fasts will likely lead to the loss of water weight. You can accomplish weight loss through these methods without adhering to a fast or cleanse regimen. What a cleanse or fast does offer is a routine, and routines usually help people lose weight. However, in this case, the routine is only temporary. You’re better off following a routine that is healthy and sustainable longterm.
The risk of relapsing
If you normally follow a relatively unhealthy diet and lifestyle, then you may be more prone to relapse after the cleanse. Some people may strive to eat healthy immediately afterwards, but slowly (or quickly) fall back into old habits. Some people even “reward” themselves by splurging, thinking their body can afford to splurge after being “cleansed” or with lost weight. You could easily regain any weight or toxins that you purged or more if your body compels you to compensate for the reduction. (See our prior article about ways your body can undo progress after extreme measures.)
Questionable longterm benefit
If you think about it, eating clean for 7 to 14 days every few months probably doesn’t benefit you much overall if you’re consuming unhealthy foods and substances most of the other time. Regularly consuming toxic or unhealthy substances can permeate your body internally and externally over time. It can manifest in places such as the quality of your skin, the amount of visceral fat you have, or autoimmune conditions. A brief fast could stall and reverse a little bit of the damage during those 1 to 2 weeks, but certainly not damage that has accumulated for months or years. Conversely, eating and living healthier for months or years on end can reverse and heal much more. (Example: this study.)
Depending on your current lifestyle and objectives, then undergoing a fast or cleanse may be unnecessary. If you lead an unhealthy lifestyle exposed to a lot of chemicals and toxins, then following a healthy diet and lifestyle permanently would be ideal. If you already lead a healthy lifestyle, then the effort put into a “cleanse” will probably outweigh the benefits. So, it basically comes down to whether you want to expend the temporary effort for questionable results.