There are many reasons why Americans eat a lot of high-calorie foods. Here are some of the main factors:

1. Fast-paced lifestyle: Americans live a fast-paced life. They often don't have much time for meals, so they tend to choose quick, high-calorie meals instead of spending more time preparing healthy meals.

2. Taste preference: Americans generally like the taste of high-calorie foods, which can satisfy their taste buds and allow them to enjoy delicious food in a short period of time.

3. Food culture: American food culture is the most important factor causing the obesity problem. Most Americans below the middle class eat hamburgers, French fries, Coke, hot dogs, pizza, barbecue, and semi-finished products from supermarkets on their daily meals. Healthy eating options (like vegetables) are too expensive for them.

4. Economic development and lifestyle: The United States has abundant supplies and every meal is sufficient. Large-scale industrial production has caused a sharp increase in grain production (mainly corn) in the United States. Excess corn is used to feed livestock, and cheap beef floods the market. Meanwhile, Japanese scientists have invented a way to turn corn into a cheap sweetener, high-fructose corn syrup, making desserts and sugary drinks sweeter and cheaper.

In general, Americans’ high-calorie diet preferences are affected by multiple factors, including lifestyle, food culture, economic development, and lifestyle.