Moderate evidence

Losing weight slowly, with adequate protein and continued resistance training, preserves lean mass and performance better than losing it fast.

In practice

An aggressive deficit costs you muscle and strength alongside the fat, and the strength loss shows up in your logged sessions. Slower is not just kinder, it's a better result.

What it doesn't say

The evidence here is from elite athletes in a controlled setting. The direction is well accepted; the exact rate that suits an individual isn't something a study can set.

Source

• Garthe I, Raastad T, Refsnes PE, Koivisto A, Sundgot-Borgen J (2011). Effect of two different weight-loss rates on body composition and strength and power-related performance in elite athletes. International Journal of Sport Nutrition and Exercise Metabolism, 21(2):97–104. doi.org/10.1123/ijsnem.21.2.97