10/16/2015 03:26 EDT | Updated 10/16/2015 03:59 EDT

Carrie Underwood Reveals The Secret To Her Flat Stomach

Hint: It has to do with her dinner.

Carrie Underwood may have just given birth in February, but she looks fantastic.

The country singer appears on the November cover of Shape magazine, and revealed in the issue how she slimmed down after her son Isaiah Fisher was born.

"After I had Isaiah, my goal was to take control of my body again. I was lucky: I gained only 30 pounds, which is the recommended amount, and I exercised throughout my pregnancy,” she told the magazine.

Less than two weeks post-baby, she was already walking on the treadmill. Now, she says, she enjoys boxing and hiking, as well as a high-intensity workout called Tabata.

But her big secret to staying trim lies in what she eats at dinnertime.

"I'm vegan and I love bread, but recently, I started making dinner a breadless meal,” she said.

“I'll have a bowl of oatmeal for breakfast, and I'll make a sandwich on Ezekiel bread for lunch, but in the evening I'll have protein and vegetables and no bread. When I wake up, my belly is flat!"

The 2005 American Idol winner also told People recently that she battled with her weight around the time of the show, admitting that she turned to weight-loss supplements to slim down and didn’t take in enough calories.

Now, she said, she takes a healthier approach.

“I weigh more than I did when I was at my smallest, but I have a lot more muscle tone,” she said.

We say kudos to Carrie for losing weight the healthy way, and for having the courage to admit to her past struggles.

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