Does eating less help your cells clean themselves more effectively?
Intermittent fasting shows preliminary signals that it modestly supports cellular self-cleaning. Simply eating less or reducing protein intake does not demonstrably do the same.
Intermittent fasting, where you only eat within a fixed window of time each day, appears to give a modest boost to your cells' self-cleaning process (the way cells break down and recycle their own waste). In a study of 121 people with severe obesity, the fasting group scored clearly better on this measure after 6 months than the group that continued eating as normal. However, a word of caution: within the fasting group itself, cell-cleaning activity did not rise clearly compared to where it started. Part of the difference came about because cell-cleaning seemed to decline in the non-fasting group. The conclusion is therefore tentative.
Simply eating fewer calories, without any fasting window, showed no measurable effect on your cells' self-cleaning in that same study. Likewise, cutting protein intake in half among 63 healthy adults changed nothing about that process, even though animal studies had predicted it would. Two direct tests in people therefore found no effect.
In type 2 diabetes, a review of several studies does describe short-term benefits of intermittent fasting on blood sugar and weight, with cell self-cleaning cited as one possible explanation. How large a role that actually plays cannot be measured separately. Discuss this with your doctor if you have diabetes and want to try fasting.
In animal studies, the picture looks more promising. A diet involving a few days of very little food slowed tumour growth in mice and rats and strengthened the effects of cancer treatments, partly through cell self-cleaning. Whether this also applies to people is not yet known.
In short: time-restricted eating provides preliminary signals of slightly more cell self-cleaning in people with obesity, but eating less without such a schedule, or simply eating less protein, does not demonstrably do the same. The effect of fasting on cellular self-cleaning in people has been little studied so far, and the evidence is thin.
This answer draws on two studies in people, two reviews of multiple studies, and two publications not further indexed. The authors of the long COVID review themselves note that findings are preliminary due to small sample sizes, short follow-up periods, and varying study designs, and that standardised follow-up research is needed. The two studies in people are relatively small, measure cellular self-cleaning in blood rather than tissue, and each used a different definition of "eating less." The evidence for fasting-induced cell self-cleaning in people is therefore still in its early stages.