Having visible abs is not just about a specific BMI number but also about having a low body fat percentage. To have visible abs, men typically need to have a body fat percentage of less than 10%, while women need to have a body fat percentage of less than 20%.
This means that you need to focus on reducing your body fat through a combination of diet and exercise. Incorporating strength training exercises that target your core, such as planks and crunches, can also help to build the muscles in your abs and make them more visible.
However, it’s important to remember that everyone’s body is different, and some people may have visible abs even with a slightly higher body fat percentage.