By Alex Kirby
BBC News Online environment correspondent
More people are adopting a lifestyle that leaves them dissatisfied and the Earth impoverished, US researchers say.
More than 1.7 billion people have entered the "consumer class"
The Worldwatch Institute says more than 25% of the world's people now enjoy the style which used to belong to the rich.
But it says rising obesity and debt, and increasing pressures on time, are reducing many people's quality of life.
In its annual report, Worldwatch says consumers' demands are devouring the natural world unsustainably, leaving the poor less able to meet their needs.
Dedicated to consumption
The latest edition of its annual publication, State Of The World 2004, says about 1.7 billion people have entered "the consumer class", adopting the diets, transport systems and lifestyles formerly the preserve of North America, Europe and Japan.
The amount spent across the world on goods and services by households has quadrupled since 1960, reaching more than $20 trillion in 2000.
LUXURIES AND NEEDS
Yearly spending on luxury items:
Ocean cruises: $14bn
Ice-cream in Europe: $11 bn
Extra annual funds needed to achieve global goals:
Eliminate hunger: $19bn
Reproductive health care for all women: $12bn
Clean water for all: $10bn
Universal literacy: $5bn
Worldwatch says consumption by the wealthy elites, and increasingly among the middle class as well, has gone beyond satisfying needs to become an end in its own right. It is also rising rapidly in developing countries, especially in China and India.
The report says consumption is not in itself bad. But it says: "Higher levels of obesity and personal debt, chronic time shortages, and a degraded environment are all signs that excessive consumption is diminishing the quality of life for many people.
"The challenge now is to mobilise governments, businesses and citizens to shift their focus away from the unrestrained accumulation of goods, and toward finding ways to ensure a better life for all."
Reversing the trend
The institute's president, Christopher Flavin, said: "As we enter a new century, this unprecedented consumer appetite is undermining the natural systems we all depend on, and making it even harder for the world's poor to meet their basic needs."
The US has more private vehicles on the road than people licensed to drive them. New houses in the US were 38% bigger in 2000 than in 1975, although average household size had fallen.
Yet only about a third of Americans described themselves as "very happy", the same share as in 1957 when US citizens were just half as wealthy.
The report says examples of environmental pressures caused by consumers include the loss of forests and wetlands, overfishing, and transport, which uses nearly 30% of world energy and 95% of its oil.
Its suggested remedies include green taxes, laws requiring industry to take back life-expired products, making goods which will last longer, and more responsible choices by individual consumers.