Weight Watchers does a body good!

Jessica Simpson is basking in post-wedding bliss on her honeymoon at the Four Seasons Punta Mita resort, and the sexy fashion mogul decided to treat her Instagram followers to a sexy bathing suit selfie and signed it with her new married name Johnson!

The blonde beauty and husband Eric tied the knot in an intimate ceremony at the San Ysidro Ranch in Santa Barbara over July 4th weekend, and the grandparents must be watching kids Maxwell and Ace while their parents celebrate their first days of married life.

"They had an amazing time and looked so in love during the entire visit. They enjoyed cocktails by the pool and spent a lot of time on the beach, just relaxing after their big day," a source told Us Weekly about their vacay.

Ex-boyfriend John Mayer famously called her "sexual napalm", and we can definitely see why!