Someone said this on the fitness reddit and I hadn't heard it, so I asked for some links and was provided for:

The research: A limit on the energy transfer rate from the hu... [J Theor Biol. 2005] - PubMed - NCBI
Previous reddit thread: Are you a beginner who wants to lose weight, wants to know what your calorie intake should be to best lose fat while retaining muscle? Here's a place to start. : Fitness
Online calculator based on both: Lose fat fast without losing muscle! • Deflab.me

Thoughts?