Jennifer Lopez, 49, looks tense on Day Four of her ‘no sugar, no carbs’ diet that has left her ‘really hungry’ as she models sports bra

Jennifer Lopez stepped out in Miami on Thursday showing off a very toned and trim body.

The 49-year-old siren was wearing a tiny periwinkle sports bra that showed plenty of cleavage along with multicolored leggings as she headed into SOMI Fitness. The Second Act actress is on Day Four of her no carbs, no sugar diet which should last a total of 10 days. Also on the plan with her is beau of two years, Alex Rodriguez.

But the diet may be affecting her mood as the singer – who has said she is ‘really hungry’ – failed to crack a smile.

Ripped Jenny: Jennifer Lopez stepped out in Miami on Thursday showing off a very toned and trim body but she didn’t appear to be in the lightest mood

Showing off what she’s got: The 49-year-old siren was wearing a tiny periwinkle sports bra that showed plenty of cleavage along with multicolored leggings as she headed into SOMI Fitness

The looker had her hair down and nicely styled as she added her signature Jenny From The Block gold hoop earrings.

And the Shades Of Blue star held onto her neon green Hermes Birkin purse.

The mother to twins Max and Emme – whom she had with singer Marc Anthony – held onto a white top and wore white sneakers.

One more week! The Second Act actress is on Day Four of her no carbs, no sugar diet which should last a total of 10 days. Also on the plan with her is beau of two years, Alex Rodriguez

The diva was dropped off by a black SUV.

J-Lo and A-Rod have now committed to a grueling new diet plan, quitting eating sugar and even most carbs.

On Wednesday she admitted she was just ‘really, really hungry’.

Posting to Instagram Stories from the treadmill during her workout, the actress explained that the program was ‘harder than I thought’, saying: ‘So, 24 hours in, no sugar no carbs, learning a lot about what sugar does to your body and just need to stay away from it.’

A bit grumpy? But the diet may be affecting her mood as the singer – who has said she is ‘really hungry’ – failed to crack a smile

In style: The looker had her hair down and nicely styled as she added her signature Jenny From The Block gold hoop earrings. And the Shades Of Blue star held onto her neon green Hermes Birkin purse

A smile for Instagram: The singer managed to put in a grin while posing for a selfie and insisted she was feeling a ‘lil better’

But post-workout she admitted: ‘So it turns out when you don’t have sugar and you don’t have carbs you’re really really hungry all the time so we’re trying to figure out a lot of really good snacks.’

She shared a picture of her chosen snacks – raw veggies, sugar-free Jello and canned tuna.

And J Lo wanted her fans to join her – challenging them to jump on the sugar-free bandaon in a joint social media message with A-Rod.

First he admitted the carb-free life wasn’t easy, saying: ‘I have had eggs andaocado today. I’m dying. I hope you are doing much better.’

Give me a croissant… a chocolate croissant: The diva was dropped off by a black SUV. J-Lo and A-Rod have now committed to a grueling new diet plan, quitting eating sugar and even most carbs. On Wednesday she admitted she was just ‘really, really hungry’

But then J-Lo perked things up, challenging some celebrity chums to join her.

She laughed: ‘So we’re just walking in from the gym, and we’re getting lonely. I’m challenging Lea Remini, I am challenging Hoda.’

It was Alex who first revealed he and his actress love were planning to go sugar and carb-free for 10 days.

He captioned Tuesday’s video, ‘We pink promise. Join me and Jennifer for a 10-day challenge. No carbs, no sugar. Who’s in?’

The father-of-two then posted to social media about the challenge again, this time holding a massive piece of meat.

‘No carbs + no sugar = lots of meat,’ he wrote before asking his followers if they would be joining in on the quest.