Jennifer Lopez is known as much for her sculpted physique as she is for her music, movie roles and romantic partners.
Her former trainer, Jay Cardiello, revealed to The Post how he helped J.Lo achieve her aspirational abs — plus the single exercise that gives you the “best bang for you buck” when it comes to your core.
Cardiello, who is also the in-house fitness advisor for the elevated wellness brand Kailo Nutrition, says consistency beats perfection when it comes to achieving a flat stomach.
“Understand that abs are built through behavior, not just crunches,” he said.
“You can’t out-train poor nutrition or chronic stress, so prioritize sustainable eating habits, quality sleep, stress management and core-focused functional movement. A flat stomach isn’t just about aesthetics — it’s about having a strong, stable core that supports your body,” Cardiello noted.
Why is a strong core a priority? The core area, also known as the lumbo-pelvic-hip complex, stabilizes both the upper and lower body, thereby improving posture, enhancing mobility and preventing injury.
All about your eating habits
Cardiello advises clients who want a cut midsection to commit to regular exercise and fueling their bodies with whole foods.
“My number one rule is: Avoid overly processed foods, added sugars, and excessive sodium, as these contribute to inflammation, bloating and fat storage, especially around the midsection,” he said.
Cardiello urges the abdominally motivated to prioritize a diet of lean protein, fiber-rich vegetables, healthy fats and complex carbs to stabilize blood sugar and reduce cravings.
“I advise clients to eat smaller, balanced meals throughout the day, avoid late-night heavy eating and limit their alcohol intake, as this can disrupt digestion and metabolism,” he added.
The ab-solute best exercise
In terms of carving out the core, Cardiello says that a simple plank hold is “hands down” (pun hopefully intended) your best bet for toning the abs.
“The plank is the most effective and simplest core-tightening exercise with the best bang for your buck,” he said. “It’s deceptively simple but incredibly powerful because it engages not just your abs, but your entire core, shoulders, glutes and even your posture muscles — all without needing any equipment.”
Cardiello notes that, in addition to being modifiable for any fitness level, the plank pose builds isometric strength and stability, tightening the core muscles to create a flat, firm appearance.
“Even holding a well-executed plank for 30-60 seconds daily will deliver noticeable improvements in core strength and overall tightness in a short amount of time. It’s efficient, low-risk and highly effective,” he said.
The plank has fans
Other experts echo Cardiello’s stance.
Harvard Health Publishing maintains that planks are more effective than sit-ups, saying the former “recruit a better balance of muscles on the front, sides and back of the body than sit-ups, which target just a few muscles.”
“Plank exercises help strengthen the entire set of core muscles you use every day, leaving you with a stronger and more balanced body,” they added.
Other must-dos for a fit figure
In addition to a balanced diet and consistent exercise, including solid plank work, Cardiello recommends healthy lifestyle habits such as stress management and high-quality sleep.
He said that everyone aim for seven to nine hours of shut-eye per night to help the body maintain muscle.
“Poor sleep elevates cortisol levels, which encourages fat storage, especially around the midsection,” he said. “It’s one of the most overlooked factors, yet it has a huge impact on both metabolism and recovery.”
He notes that chronic stress keeps the body locked in a cortisol-spiking “fight or flight” mode that can lead to emotional eating and compromised digestion. “I recommend integrating breathwork, meditation or even just daily walks to bring stress levels down.”
A little supplementation
While he acknowledges that there’s no “magic pill” in terms of supplements, he takes magnesium glycinate to aid in relaxation and promote sleep quality, omega-3 fatty acids to reduce inflammation, which can contribute to belly fat retention, and a probiotic to support gut health as “digestion and bloating can directly affect how flat your stomach appears.”
But he stresses that a consistent approach to health is more beneficial than any single element or exercise.
“The real key is consistency — small, sustainable habits repeated daily will get you much further than any quick fix.
