It’s a common and oh-so-frustrating outcome for many dieters: You concentrate on calorie restriction and lose a few pounds only to see the weight come soaring back. The interaction between calorie restriction and mitochondria—important cellular power plants—may help explain why so many diets fail to produce lasting results.

An international study coordinated by the University of Helsinki, Finland, and published in The Journal of Clinical Endocrinology & Metabolism suggests that calorie restriction impairs the mitochondrial pathways in the fat tissue, reducing the expression of genes involved in their production. And since mitochondria are key to cellular energy production, a drop in their activity level can encourage the packing on of more pounds after weight loss.

Future research will hopefully uncover ways to combat this metabolic drift, making dieting more impactful in the uphill battle against obesity.

See also: Mitochondria: Unpacking Cellular Power