lose steamのsteamは、もちろん「蒸気」という意味ですが、SL（steam locomotive）が走っている姿を見ると誰しもが感じる「活力、精気、元気」という比喩です（と書いても若い人にはピンとこないかな）。
Noda appears tired, sometimes drinks a lot, sources say
Suggestions have arisen that Prime Minister Yoshihiko Noda, who has on more than one recent occasion been heard slurring his speech, is tired out.
"I explained something to him, but it didn't seem to be going into his head. He was terribly tired," a government official commented, recalling his talk to the prime minister about an important policy.
On Nov. 2, Noda was heard slurring his words while speaking in the House of Councillors, a day after he did the same in the House of Representatives.
Talk has also arisen about the amount of sake Noda has been drinking at his official residence. Sources close to the prime minister said that some days he drinks a whole bottle of sake -- roughly 1.8 liters. Though Noda has been known as a heavy drinker, one aide suggested that he has lost vigor recently.
"The law on increasing the consumption tax has passed, and perhaps he's lost steam," the aide said.
Roughly three months have passed since the law, on which Noda staked his political career, came into effect. Since then, politicians have continued to leave his ruling Democratic Party of Japan, and handling the government administration has become difficult for him.
In an interview with reporters on Nov. 2, Noda denied that tiredness was the reason for his slurred speech.
"It has nothing to do with tiredness. It just happens sometimes," he said.