"I left it too late, I'm just gutted," she told BBC Sport.
"It really kicked off with about 500m to go. I was really relaxed and comfortable and I didn't want to go too early.
"But they were a little too ahead of me. But if you had asked me this time last year whether I would be fourth in an Olympic Games, I would not have believed you and I take heart from that."
The race began at a steady pace with Russia's Anna Aliminova leading the field for the first part and Dobriskey settling in the pack and near the back.
With a lap remaining Jamal made her move and looked to be heading for victory, but she had not banked on Langat who stayed with her before sprinting clear and finishing in a time of four minutes 00.23 seconds.
"I'm very proud I was able to win gold," said Langat.
"The race was tough. It was not expected but I'm very happy."
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