Is Jessica Alba fat? No. Of course not. Jessica Alba is not fat, she is pregnant, but she seems to have unfounded fat fears. She is six months pregnant and she is exercising like crazy. Jessica has been hitting Emerson Hall Fitness in LA – and she has not been taking it easy at all.

“It’s like she’s training for a marathon,” says an eyewitness at the gym. “It doesn’t look normal, a pregnant woman exerting herself that much. Trainers tell pregnant women not to overdo it, but she’s not listening.”

A preoccupation with weight is nothing new for her. Jessica has admitted to once struggling with an eating disorder. Now, noticing the drastic changes in her body, she is again determined to look thin, says an industry insider. “It’s no wonder she’s freaking out – her body is what helps make her a star,” says the insider.

As we all know, exercising during pregnancy can be perfectly healthy. “Low-impact is good, but it depends which trimester you’re in,” says Dr. Craig Title of the New York Specialists in Medical Weight Control. “Near your second and third trimesters, you should avoid vigorous activity. Whatever stresses your system could also stress the fetus.”

Jessica, who is entering her third trimester, doesn’t seem worried, though. “Every day, as she gets bigger, she exercises more,” says the pal. “She feels pressure to look good pregnant.”

Jess also wants to make sure she has a hot post-baby bod. “She thinks that if she doesn’t work out a lot now, it’ll take longer to get skinny later,” says a pal. “She wants to look like Nicole Richie.” [via]