In 2016, a Japanese cell biologist named Yoshinori Ohsumi won the Nobel Prize in Physiology or Medicine for his research into a process called autophagy, which is the body's built-in mechanism for consuming and recycling its own damaged or dysfunctional cells. The word comes from the Greek for self-eating. When the body is not busy digesting food, it shifts focus to maintenance and repair, breaking down old proteins, malfunctioning components, and toxic buildup that contribute to aging and disease. Ohsumi demonstrated that fasting triggers this deep cellular reset, essentially initiating an internal cleanup system.
This matters to anyone in the juice and elimination diet world, and here is why.
What Ohsumi proved at the cellular level is something that practitioners of fasting, juice cleansing, and reduction diets have understood experientially for a very long time. When you stop flooding the body with food, particularly the processed, chemical-laden, hard-to-digest kind, you create a window. In that window, the body stops spending its energy on digestion and starts spending it on repair. Autophagy becomes especially active under conditions of stress and food deprivation, and in that state the cell produces energy by consuming its own internal waste, including pathogenic bacteria.
A juice cleanse works on the same principle, with one important distinction. Water fasting creates the most direct and immediate trigger for autophagy because there is nothing coming in that requires any processing at all. The body has no choice but to turn inward and begin consuming its own cellular debris. Juice, even cold-pressed, organic juice, still contains natural sugars, enzymes, and micronutrients that the body registers and processes. This does not stop autophagy from occurring, but it moderates it. The body is receiving some input, which means it is partially occupied, and the self-consumption process, while still underway, moves more slowly than it would on water alone.
Think of it as a dial rather than a switch. Water fasting turns the dial all the way up. Juice cleansing turns it up significantly, far beyond what any normal diet allows, but not to the maximum. An elimination or reduction diet turns it up less than that, but still meaningfully higher than the standard American diet, which barely lets the body catch its breath at all.
So the cleanse still works. The repair still happens. The immune system still gets a reset. It just takes longer to get to the same depth that water fasting reaches more quickly. For most people, juice is also a more sustainable and accessible entry point, which means they will actually do it, and doing it imperfectly is always going to outperform the perfect protocol that never gets started.
The body is not broken. It is waiting for a window to heal itself, and when you give it that window, in whatever form you can manage, it will use it.