Ostapchuk, 31, was given a lesser sentence than a standard two-year ban after her coach Alexander Yefimov admitted intentionally spiking her food with the steroid.
"Yefimov confessed he had put the banned drug metenolone into Ostapchuk's food without her knowledge because he was worried by her performances in the lead-up to the London Games," NADA head Alexander Vankhadlo told a news conference.
Yefimov has received a four-year suspension for his part in the doping case.
"He had admitted his guilt," added Vankhadlo.
Ostapchuk has denied any wrongdoing, saying she was tested twice before competing in London and both tests returned negative results.
"In total, I've been tested 16 times since April. You must be a complete idiot to take doping just before the competition especially such an outdated drug as a steroid, knowing you're going to be tested not once but probably several times," Ostapchuk said last month.
Ostapchuk, who had won the Olympic gold with a throw of 21.36 metres, was world champion in 2005 and European champion two years ago. In July, at a meeting in Minsk, she threw 21.58, the best outdoor distance in the world since 1998.
New Zealand's Valerie Adams, who finished second behind Ostapchuk in London, was awarded gold, with Russian Evgenia Kolodko promoted to silver and China's Gong Lijiao getting the bronze medal.