Crunches help you lose weight only if you include them as part of a comprehensive exercise routine and commit to a healthy, calorie-controlled diet. Crunches strengthen muscles that lie underneath excess fat.
When you lift and lower your torso, the movement is relatively small and doesn't burn a notable number of calories, which is essential in losing weight. Don't abandon crunches and other abdominal exercises entirely, but make them just one part of your body-transforming strategy.
How You Lose Weight
Weight loss really is a matter of calories consumed versus calories burned. Take in fewer calories through food and beverages than you burn via exercise and daily activities to lose weight.
A daily deficit of 500 to 1,000 calories yields 1 to 2 pounds lost per week. In the first couple of weeks of dedication to a new eating and exercise routine, you might drop extra water weight as your body adjusts to workouts and healthier foods. You can expect to lose 5 to 10 pounds in a month safely and sustainably at this rate.
Creating a Caloric Deficit
Calorie quality counts as you drop pounds. Eat mostly whole, unprocessed foods, such as lean proteins, vegetables, fruits, whole grains, low-fat dairy and small amounts of healthy fats found in nuts and avocados.
Chicken breast, fish, lean steak, low-fat cottage cheese, leafy greens, berries, brown rice, quinoa and almonds make for go-to weight-loss meal ingredients.
For many people, simply eating 500 to 1,000 calories fewer per day leads to too few calories consumed. You want to create a deficit, but not eat fewer than 1,200 calories daily if you are a woman or 1,800 calories if you are a man or risk lowering your metabolism and sabotaging weight loss.
Increased physical activity can help you further the deficit without starving. Crunches, however, aren't going to do much to further your calorie burn. In one minute of crunches, a 150-pound, 5-foot, 5-inch woman burns about 5 calories.
Crunching more than a few minutes isn't productive or realistic. In one minute of running at a 6 mph pace — 10 minute miles — the same person burns 11 calories. Running is something you do 20 minutes or longer -- so you burn considerably more calories to contribute to a calorie deficit.
Comprehensive Strength Training, Not Just Crunches
Crunches address just one set of muscles — your abdominals. While this might be where you want to slim down, research has shown time and again that exercising a specific area doesn't lead to fat loss there.
The Journal of Strength Conditioning and Research published a study in 2011 showing that six weeks of abdominal exercises did not reduce abdominal fat or alter body composition in men or women.
A total-body strength training program, that might include crunches as one exercise, does positively affect weight loss, though. Current Sports Medicine Reports published research in 2012 asserting that 10 weeks of regular training can help you lose 4 pounds of fat and increase metabolism by as much as 7 percent.
Target all the major muscle groups, which include the back, chest, arms, shoulders, legs, hips and abs, at two to three workouts per week. Choose exercises that move multiple muscle groups at once, such as squats, presses and pulls.
Use weights that feel heavy by the last couple of efforts in at least one set of eight to 12 repetitions. Do a set of crunches as part of your routine, but don't let it be your sole strength-training or weight-loss strategy.