It seems to be more complicated (or unpredictable?) than that:
> In this study, rapid weight loss was associated with the loss of kidney function in males with normal weight, and with improvement of kidney function in overweight males.
> Our study showed that BMI and BMI change were not associated with eGFR change in females.
It seems to be more complicated (or unpredictable?) than that:
> In this study, rapid weight loss was associated with the loss of kidney function in males with normal weight, and with improvement of kidney function in overweight males.
> Our study showed that BMI and BMI change were not associated with eGFR change in females.
https://pmc.ncbi.nlm.nih.gov/articles/PMC4658128/