… that low-fat diets result in more body fat loss. I blogged about this in March 2015 before the study was published (New Study: Low-Fat Diet Burns More Body Fat Than Low-Carb Diet). It was eventually published:

Calorie for Calorie, Dietary Fat Restriction Results in More Body Fat Loss than Carbohydrate Restriction in People with Obesity, Cell Metabolism, September 2015

Dietary carbohydrate restriction has been purported to cause endocrine adaptations that promote body fat loss more than dietary fat restriction. We selectively restricted dietary carbohydrate versus fat for 6 days following a 5-day baseline diet in 19 adults with obesity confined to a metabolic ward where they exercised daily. Subjects received both isocaloric diets in random order during each of two inpatient stays. Body fat loss was calculated as the difference between daily fat intake and net fat oxidation measured while residing in a metabolic chamber. Whereas carbohydrate restriction led to sustained increases in fat oxidation and loss of 53 ± 6 g/day of body fat, fat oxidation was unchanged by fat restriction, leading to 89 ± 6 g/day of fat loss, and was significantly greater than carbohydrate restriction (p = 0.002).

Lead study author Kevin D. Hall, PhD, senior investigator at the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) of the National Institutes of Health (NIH) in Bethesda, Maryland:

“Calorie for calorie, reducing dietary fat results in more body fat loss than reducing dietary carbohydrate when men and women with obesity have their food intake strictly controlled.”

The researchers measured the amount of fat eaten and the amount of fat burned. The difference between them determined how much fat was lost from the body.

Here’s a graphic from the study:

Compared to the reduced carbohydrate diet, the reduced fat diet (same number of calories) led to a roughly 67% greater body fat loss.

This is a similar study to the one I just posted (Gary Taubes Is A Low-Carb Advocate. His Multimillion-Dollar Start-Up, NuSI, Found Low-Carb Diets Don’t Work.), a metabolic ward study where intake and expenditure are well controlled, same lead author, similar group of researchers, same finding … low-carb diets don’t lead to more body fat loss.