Noting that reduced-calorie diets are often difficult to follow because they often require elimination of certain foods, the researchers suggested that dieters could allow themselves a daily snack without "without exceeding energy requirements, even during weight loss".

The 18-week pilot study of 26 overweight and obese pre-menopausal women, at Pennsylvania State University, evaluated the effects of a reduced-calorie diet, including either a daily dark chocolate snack or a non-chocolate snack.

At baseline and end of study, body weight and waist and hip circumferences were measured along with fat mass, lean mass, and body fat percentage.

The researchers gound that women in both snack groups reduced estimated daily energy intake, while women in both the dark chocolate snack and non-chocolate snack groups registered decreases in body weight.

"Improvements in anthropometric and body composition measurements among overweight and obese premenopausal women can be achieved with a reduced-calorie diet including either a daily dark chocolate snack or non-chocolate snack," the scientists concluded.