It’s a problem that has plagued thousands if not millions of dieters: “How come it’s so much harder for me to lose weight than some other people? And when I do get it off, how come it’s so easy for me to gain it back?” It turns out scientists have been asking that question too, and they are beginning to have some answers.

University of Navarra scientist Estíbaliz Goyenechea Soto just released a study (regrettably only available in Spanish) showing that some obese people have a genetic mutation which makes it harder for them to lose weight and keep it off. A related problem occurs when excess body fat causes there to be too many inflammatory substances in the bloodstream. Readers are cautioned that this is not an excuse to be obese, but usually combines with “external and personal factors such as inadequate dietary habits or physical inactivity.”

The good news is that these patients can be identified. It is now possible to pull a little blood and figure out how that person is likely to respond to a reduced calorie diet. This test is not available in your doctor’s office or local diagnostic center yet.

Identifying people who will have trouble with a diet is of course only the first step. Using the information from such tests, doctors and dietitians should someday be able to get patients a highly individualized diet plan that has a far greater chance of long term success than any diet book you’ll be able to purchase in a bookstore. Sorry, no magic pill or hormone shot to make you skinny will come out of this.

Her Take: On one hand, this is a huge breakthrough! We are finally able to separate the people who “just can’t stay on a diet” from the people with genuine genetic and metabolic issues that keep diets from working right. If highly individualized diets help these people get to a normal weight and stay there, it will greatly reduce their risk of diabetes, hypertension, coronary artery disease, cancer, stroke, and a host of other debilitating problems. On the other hand, having support is a critical factor for making a diet or any other lifestyle change work, and families rarely have only one obese member. How is dinner going to work with Dad and Mom and maybe even Junior being on different diet plans? How are they going to keep on the plan if they all have different dietary needs for weight loss?

His Take: None of this seems particularly surprising to me clinically. The really, really obese have always had a much tougher time getting rolling on weight management plans than merely overweight people. This insight, that it’s the inflammatory compounds resulting from high levels of body fat that work to keep the fat on may yield some approaches to manage that inflammation to make getting the fat off less difficult.