The Dietary Guidelines for Americans were guided by the reality that about ______ of U.S. adults are obese or overweight.

The correct answer is based on the statistic which reflects a significant public health concern regarding obesity and overweight in the U.S. population. The Dietary Guidelines for Americans take into account the reality that approximately two-thirds of U.S. adults are considered to be obese or overweight. This figure underscores the urgency for nutritional guidelines that promote healthier eating patterns and lifestyle changes to combat obesity and its associated health risks.

Understanding this context is essential, as it informs the importance of developing dietary recommendations aimed at improving the health of the population. The focus on addressing obesity through these guidelines is intended to help reduce the prevalence of chronic diseases linked to excessive body weight. This is why the statistic of two-thirds is particularly relevant—it highlights the extent of the issue and the need for proactive measures in public health nutrition.