Although it doesn’t come to a surprise to anyone to find out that the overall waist size of Americans has been steadily increasing over the last quarter of a century, but additional research has suggested that it is over more recent years that there has been a more specific trend with a more precise reason behind it.

The results of the study were published in a paper in the American Journal of Clinical Nutrition. Within that research, scientists examined the average waist measurements of the women and men who took part in the National Health and Nutrition Examination Survey between the years of 1999 and 2012. They also recorded the body mass indexes (BMIs) of the participants.

Upon conducting a comparison analysis of the waistlines measurements and BMIs of the participants, the researchers concluded that there was an average growth of 1.5 inches in the waistlines of women, while men saw an increase in their waist sizes by only 0.75 inches. Moreover, the largest increases among waist sizes in women occurred in those under the age of 40 years.

At the same time, the BMIs of men rose by 0.7 while those of women went up by an average of only 0.6. The scientists asked the question of why women are seeing a slower increase in BMI despite the fact that they are clearly increasing around the middle at a much faster rate. Unfortunately, they didn’t come up with a conclusive answer for that question. However, at the same time, the authors of the study indicated that research that had previously been conducted had linked the occurrence of larger middles with other types of struggles such as sleep struggles, stress, depression, side effects from some medications, and even from yo-yo dieting.

Therefore, it could be that because of some reasons that aren’t quite obvious, women are putting on size around the middle despite the fact that they’re not actually bulking up with a large number of pounds.

This does suggest that women may need to pay attention to a larger number of factors in their lives than simply measuring their waistlines and stepping on the scale to determine how their health and weight are doing. They may benefit from speaking with a doctor about overall lifestyle habits and common issues in their lives such as stress, insomnia, mental health issues, and other factors that could be causing them to gain size around the middle and make it harder for them to lose. It could be that coping with those factors, combined with healthy eating and exercise, could be more effective than dieting, alone.