Final answer:
Obesity is the most frequent nutritional problem in the United States, caused by excessive energy intake and inadequate energy expenditure. It is associated with various health problems and diseases.
Step-by-step explanation:
The most frequent nutritional problem in the United States is obesity. Obesity is caused by excessive energy intake and inadequate energy expenditure, resulting in people becoming overweight or obese. It is associated with various health problems and diseases such as metabolic syndrome, cardiovascular disease, type 2 diabetes, and certain types of cancer.