The 23-year-old often bulks up between the weigh-in and the fight and is used to fighting at a higher weight than Mayweather.
However, the pound-for-pound king and welterweight champion has insisted on a limit of 152lbs, which Alvarez thinks might be a positive.
"It's not going to bother me at all," said the unbeaten Mexican at a press conference. "I feel good. I feel very, very good.
"I've been able to make the weight in the past without a problem. In fact, in my most recent fights I've been under on the day of the weigh-in.
"I really don't do that much work so I think that it's going to be fine. I feel very, very good right now, and in fact I think it's going to help me. I'm going to be a lot faster."
Alvarez takes on Mayweather in Las Vegas on September 14.