It's the idea you need a caloric deficit of 3,500 kcal in order to lose 1lb of fat that they're describing as 'overly simplistic', based on this study: https://

It's the idea you need a caloric deficit of 3,500 kcal in order to lose 1lb of fat that they're describing as 'overly simplistic', based on this study: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4035446/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4035446/ At the end of the day, weight loss is still calories in, calories out -- as frustrating as that can be.