Spot gold was flat at $1,431.20 an ounce at 1125 GMT, while US gold futures edged 0.2% higher to $1,432.20.
Expectations for an interest rate cut by the Fed and other leading central banks, which would cut the opportunity cost of holding non-yielding gold, have put the metal on track for a 1.5% gain for July.
Fed funds rate futures are now fully pricing in an interest rate cut of 25 basis points on Wednesday, which would be its first since the financial crisis more than a decade ago, and reduction of a further 25 basis points by September.
"The gold market will focus more on the communication, whether the Fed leaves the door open for more rate cuts later this year citing global growth worries," said Julius Baer analyst Carsten Menke.
"This may lead to some more upside in gold prices."
The Fed's decision is due at 1800 GMT, with Chair Jerome Powell scheduled to hold a press conference soon after.
Backing the Fed's dovish policy tilt, US consumer spending and prices rose only moderately in June, pointing to slower economic growth and benign inflation.
"Should the FOMC surprise either via a 50 bp rate cut or a more dovish tone than expected, the key top-side target for bullion remains at $1,450," industrial and trading services group MKS PAMP said in a note.
"Aside from the FOMC meeting, there remain a number of ongoing risk events to provide price direction to bullion, namely the increasing likelihood of a no-deal Brexit and a lack of progress between the US and China in trade negotiations."
US President Donald Trump warned China against waiting out his presidency before finalising a trade deal, saying the outcome could be no agreement or a harsher one if he wins re-election in November 2020.
"We have quite a strong link here between the trade talks and the outlook for US monetary policy. The longer the trade tensions drag on ... the more we need support from the Fed on the interest rate side," Julius Baer's Menke added.
Among other precious metals, silver slipped 0.7% to $16.46 an ounce and platinum jumped 0.9% to $873.71, both on track for a second straight month of gains.
Palladium rose 0.8% to $1,527.03.