August 28, 2025, 1:51 pm | Read time: 4 minutes
Many swear by countless sit-ups to get rid of belly fat–but that’s exactly where the misconception lies. Ab exercises alone are not enough to reveal a defined six-pack. Why this is the case, the role of energy expenditure, and why longer workouts are often more effective are explained by sports scientist Jörn Giersberg in an interview with FITBOOK.
How many sit-ups and crunches Cristiano Ronaldo has done in his life for his perfect six-pack, with no trace of belly fat, is unknown. However, the number is likely easily in the five figures. But anyone who thinks that daily ab exercises alone are enough is mistaken. The soccer star serves as a perfect example of what really makes up the overall picture of a washboard stomach.
Join the big FITBOOK survey!
Pure Ab Exercises Not Intense Enough
“The key lies in energy expenditure,” says sports scientist and personal trainer Jörn Giersberg. What does he mean by that? Well, only those with a low body fat percentage will eventually have visible abs. “Fat loss primarily occurs through metabolism. If I want to boost energy expenditure, I need to activate muscles.” Specifically, the type of muscles that are particularly efficient at burning fat.
Pure ab exercises are only somewhat suitable for this because they are simply too low in intensity.
You Can’t Target Fat Loss in Specific Areas
While our body uses body fat as an energy source during exercise, it doesn’t specifically target belly fat. It draws from all over, in all body regions. The idea that sit-ups or other ab exercises can specifically melt away belly fat is a myth.
Longer Workouts Instead of a Single Exercise
Results only show with longer workouts. Giersberg tells FITBOOK: “Ab exercises are quite short and snappy. An ab workout, even if it’s intense, can’t be compared to an hour of jogging, swimming, or cycling.” Only after about 40 minutes does the body begin to activate fat metabolism and attack fat. With sit-ups or crunches, however, “it’s more the energy stores in the muscles” that are stimulated, according to the expert.
Also interesting: The most effective ab exercises for a toned stomach according to studies
The Myth of Sit-ups Against Belly Fat Persists
The belief that a lot of sit-ups will quickly melt away belly fat is something Giersberg encounters frequently. Some people trying to lose weight work on their “problem areas” almost daily–but with little satisfying results. “Additionally, muscles can’t develop optimally,” he adds. “That only happens during recovery.” Those who stimulate their abs with high-frequency sit-ups daily essentially hinder muscle growth.
If You Want to Lose Belly Fat, You Should Focus on Training Two Other Parts of Your Body
How Many Sit-ups Women and Men Should Be Able to Do
The Risk of Too Many Sit-ups
Too many sit-ups daily are not only unfavorable for muscle growth. Because they also involve the lower back, sit-ups can cause back pain. Joints, tendons, and ligaments can be affected. Giersberg warns: “If you do it constantly, the passive musculoskeletal system can’t recover adequately.”
Excessive strain on the abdominal muscles can even lead to the midsection gaining size and appearing wider. “If you do too much, the muscles may build up too much, and you might look even bulkier in the middle,” Giersberg cautions.
Less Belly Fat–Expert’s Recommendation
The expert therefore recommends keeping energy expenditure up through muscle building and proper nutrition to keep the metabolism going. According to Giersberg, a mix of strength training and cardio is ideal for getting rid of excess belly fat. However, it shouldn’t be too much endurance training, “to not sabotage muscle building.”