Low-calorie diets affect men's and women's bodies differently, study shows

Men's bodies may respond better to low-calorie diets than women's, a new study showed.

A study in Denmark recruited more than 2,000 people who had pre-diabetes -- meaning high blood sugar, but not yet diabetes -- to look at how low-calorie diets worked for them. In the study, researchers from the University of Copenhagen found that men benefitted in more ways from the reduced calorie counts, and not just in the numbers on the scale.

"Despite adjusting for the differences in weight loss, it appears that men benefited more from the intervention than women. Whether differences between genders persist in the long-term and whether we will need to design different interventions depending on gender will be interesting to follow," said lead author Dr. Pia Christensen, of the University of Copenhagen.

After eight weeks on the low-calorie, high-protein diet, all participants had lost about 10 percent of their body weight and gained control of their blood sugar, researchers said. In addition, men lost significantly more body fat than women, had improved resting heart rate, lower bad cholesterol and had lost a few inches off their waist.

Women, on the other hand, had some negative effects in addition to the weight loss. They saw decreases in good cholesterol, or HDL, lean body mass and bone-mineral content -- none of which is good for long-term health.

Both genders saw a decrease in inflammatory biomarkers, which led to improvement in blood flow.

Does this study mean women should not adhere to a low-calorie diet? No.

Weight loss can curb diabetes, but women should understand rapid weight loss may have long term implications. It's important to eat a different and more balanced diet after this kind of rapid weight loss, and work with doctors to monitor overall health.

A total of 86 million adults in the U.S. have pre-diabetes, according to the Centers for Disease Control and Prevention. In this condition, blood sugar is higher than normal, but not high enough yet to classify as type 2 diabetes. Pre-diabetes has been associated with a higher risk of heart disease and stroke, it can lead to a future full of insulin shots and doctors’ visits which may eventually include diabetes.

"Progression of type 2 diabetes can be prevented by lifestyle modification," Dr. Joann E. Manson, chief of the division of preventive medicine at Brigham and Women's Hospital in Boston, Massachusetts told ABC News. "Most importantly, lose weight and become physically active."

But, it's important for people with pre-diabetes to recognize that it it's easy for it to progress to diabetes and they need to stay vigilant.

"If you tell people that they don't have diabetes yet, they think 'Oh good.' They take that loophole," Anne Daly, past-president of health care and education for the American Diabetes Association, told ABC News. "We don't want people to take that loophole."

Managing weight loss includes diet changes and exercise, as well as consulting with health care professionals.

"In order to create a calorie deficit, which is how you lose weight, you've got to decrease what's coming in the door and increase what's going out the door," Daly added. "You need to work on both sides of that energy equation. You can try to be a couch potato and eat like a bird, but it isn't going to work."

Aditi Vyas, M.D., specializes in radiology and occupational and environmental medicine and is a resident in the ABC News Medical Unit.