Jessica Simpson dazzled her Instagram followers last night as she posed in a lyrca bra and knickers that showed off how she's managed totally transformed her figure in the last year.

After welcoming her third child Birdie Mae in March 2019, Jessica tipped the scales at 17 stone.

The 39-year-old then went to visit LA trainer Harley Pasternak who came up with a sustainable plan to help Jessica get back to fitness and her pre baby weight.

One of the challenges Jessica was set was to walk 14,000 steps every day.

Jessica wowed fans with her latest Instagram snap
The star gave birth to her third child in March 2019

Harley describes walking the 'ultimate fat-burning exercise.'

"It had to be more than just getting back from her baby weight, but how do I keep whatever I am doing now forever," trainer Harley explained to E! News.

"That's why we are not a big fan of doing any extreme diet or radical forms of exercise."

Harley previously told how he used a five daily behaviours program with Jessica.

Harley credits walking as the 'ultimate fat burning' exercise that helped transform Jessica's curves

This is made up of keeping to the daily step count, getting seven hours of a sleep every night and unplugging from technology for at least one hour every day.

The other two principles are eating three meals and two snacks - which are protein and fibre heavy - and doing resistance workouts every other day.

Following this regime Jessica managed to lose seven stone in six months - despite that not even being her goal.

Jessica lost seven stone in six months

Explaining the exercise regime, Harley said: "Working out with resistance exercise is the best way to tone, tighten, and strengthen.

"But to lose weight, nothing can beat walking. Both of these are essential to get the goals that you want."

Jessica's diet usually consists of scrambled eggs and a bowl of blackberries for breakfast.

Followed by grilled chicken and salad for lunch and grilled fish and vegetables for dinner.

In between meal snacks include almonds or green beans with Parmesan cheese on top.

Harvey said it was important for Jessica to give her body everything it needs rather than to starve herself.