Consumer buying is responsible for about two-thirds of the U.S. Gross Domestic Product (GDP). Unfortunately, more clues are rising that point to a "tapped-out" and "over-borrowed" consumer. Here are some recent gauges of poor consumer demand for goods:

-- Yesterday, Wal-Mart announced it was lowering its sales forecast for August. It expects sales to be either flat or 2% higher -- very poor results compared to what analysts had expected. The company cited lost sales in Florida due to Hurricane Charley and lower-than-expected back-to-school sales.

-- Consumer spending in June fell 0.7%, the biggest monthly drop since the September 11, 2001 terrorist attacks. Consumer purchases of long-lasting durable goods like appliances and cars actually fell 5.8% in June. When adjusted for inflation, consumer spending fell 0.9% overall in June.

-- The price chart of the Dow Jones Retail Index shows a breakdown in the price of major retail stocks. Remember, stocks are leading indicators. Right now, the retail stocks are looking forward and not liking what they see.

While some analysts are blaming the higher price of oil for the weak demand for goods by consumers, gas prices have not risen as fast as oil prices. There are obviously other reasons for the slowdown in consumer spending. The frightening aspect of the current situation is the relationship between slowing consumer demand and low interest rates. One would think that with interest rates at about a 40-year low, consumers would spend, spend, spend! But maybe there's no money left to spend and no more room to borrow.

Weak U.S. consumer spending reports are expected for July and August. And I'm keeping my eye on auto sales to see just how far consumers cut back during these times of unprecedented auto sales incentives. The only sector where consumer demand has not weakened is new and resale homes. If demand in this sector starts to ease, there will be great damage to the economy.