Explain the disease to help US citizens In 2008, Barack Obama told the US people the nation's economic crisis would take a long time to overcome. In 2012, many of those voters are losing patience, because they have not been told why this recession has lasted so long or why his polices were the correct response. Here is the missing explanation - based on not only the US experience, but also that of Japan and Europe. Today, the US private sector is saving a staggering 8 per cent of gross domestic product - at zero interest rates, when households and businesses would ordinarily be borrowing and spending money. But the US is not alone: in Ireland and Japan, the private sector is saving 9 per cent of GDP; in Spain it is saving 7 per cent of GDP; and in the UK, 5 per cent. Interest rates are at record lows in all these countries. This is the result of the bursting of debt-financed housing bubbles, which left the private sector with huge debt overhangs - notably the underwater mortgages - giving it no choice but to pay down debt or increase savings, even at zero interest rates. However, if someone is saving money or paying down debt, someone else must be borrowing and spending that money to keep the economy going. In a normal world, it is the role of interest rates to ensure all saved funds are borrowed and spent, with interest rates rising when there are too many borrowers and falling when there are too few. But when the private sector as a whole is saving money or paying down debt at zero interest rates, the banks cannot lend the repaid debt or newly deposited savings because interest rates cannot go any lower. This means that, if left unattended, the economy will continuously lose aggregate demand equivalent to the unborrowed savings. In other words, even though repairing balance sheets is the right and responsible thing to do, if everyone tries to do it at the same time a deflationary spiral will result. It was such a deflationary spiral that cost the US 46 per cent of its GDP from 1929 to 1933. Those with a debt overhang will not increase their borrowing at any interest rate; nor will there be many lenders, when the lenders themselves have financial problems. This shift from maximising profit to minimising debt explains why near-zero interest rates in the US and EU since 2008 and in Japan since 1995 have failed to produce the expected recoveries in these economies. With monetary policy largely ineffective and the private sector forced to repair its balance sheet, the only way to avoid a deflationary spiral is for the government to borrow and spend the unborrowed savings in the private sector. Japan, which also struggled with this form of balance sheet recession, managed to keep its GDP above the bubble peak of 1990 despite plunging commercial property values and rapid private sector deleveraging, because its government borrowed and spent private sector savings. The fiscal stimuli in G20 countries after the collapse of Lehman Brothers similarly averted a collapse of the global economy. Recovery from this type of recession takes time because the flow of current savings must be used to reduce the stock of debt overhang, necessarily a long process when everyone is doing it at the same time. Since one person's debt is another person's asset, there is no quick fix: shifting the problem from one part of society to another will solve nothing. The challenge now is to maintain fiscal stimuli until private sector deleveraging is completed. Any premature attempt to withdraw that stimulus will result in a deflationary implosion - as in the US in 1937, Japan in 1997, and Spain and the UK most recently. Japan's attempt in 1997 to reduce its deficit by 3 per cent of GDP - the same size as the "fiscal cliff" now facing the US - led to a horrendous 3 per cent drop in GDP and a 68 per cent increase in the deficit. At that time, Japan's private sector was saving 6 per cent of GDP at near zero interest rates, just like the US private sector today. It took Japan 10 years to climb out of the hole. Average citizens find it hard to understand why the government should not balance its budget when households and businesses must all do so. It is risky for politicians to explain but, until they make it clear that the economy will implode if everybody is saving and nobody is borrowing, public support for the necessary fiscal stimulus is likely to weaken, as seen during the past four years of the Obama administration. The US economy is already losing forward momentum as the 2009 fiscal stimulus is allowed to expire. There is no time to waste: the government must take up the private sector's unborrowed savings, to keep the economy from imploding and to provide income for businesses and households so they can repair their balance sheets. Fiscal consolidation should come only once the private sector has repaired its finances and returned to profit-maximising mode. Once the nature of the disease and its cure are explained, Americans will feel better: they are moving in the right direction, even though the journey is a long one. The writer, a former New York Fed economist, is the chief economist of Nomura Research Institute in Tokyo