Leg raises strengthen your abdominal and hip flexor muscles, but they do not selectively burn fat off your midsection. The idea that exercising a specific body part melts the fat sitting on top of it, known as spot reduction, has been tested repeatedly and comes up short in controlled research. A systematic review with meta-analysis pooling 37 comparisons found a pooled effect size of essentially zero for localized fat loss in trained versus untrained body regions.1Human Movement. A proposed model to test the hypothesis of exercise-induced localized fat reduction (spot reduction), including a systematic review with meta-analysis That does not mean leg raises are useless, far from it. But if your goal is a flatter stomach, understanding what leg raises actually accomplish and what they don’t will save you from spinning your wheels.
What Leg Raises Actually Work
When people talk about leg raises for belly fat, they usually picture lying on their back and lifting both legs toward the ceiling. The assumption is that the “burn” felt in the lower abdomen means fat is being torched in that area. In reality, that sensation comes from muscles working hard, not from fat cells disintegrating underneath them.
Electromyography studies show that during a straight leg raise, the primary movers are the hip flexors, specifically the psoas major and rectus femoris. The psoas major shows its highest activation toward the end range of hip flexion and is significantly more active than the rectus femoris throughout the movement.2Journal of Electromyography and Kinesiology. Differential activation of psoas major and rectus femoris during active straight leg raise to end range The abdominal muscles, particularly the obliques and transverse abdominis, do engage during leg raises, but their role is mainly to stabilize the pelvis and spine rather than to drive the leg-lifting motion itself. Bilateral leg lifts activate the abdominals more than unilateral ones, while the hip flexors are highly activated in any exercise involving hip flexion.3PubMed. Abdominal and hip flexor muscle activation during various training exercises
So leg raises are a solid exercise for building hip flexor strength and core stability. They challenge the abdominals isometrically, which has real value for posture and athletic performance. But they are a low-calorie-burn movement compared to large-muscle, whole-body exercises. You are moving a relatively small load through a limited range, which limits total energy expenditure per set. That distinction matters when the goal is fat loss.
Why Spot Reduction Mostly Fails
The idea that you can choose where your body drops fat by exercising that region has intuitive appeal but weak evidence. The meta-analysis mentioned earlier found that of 37 comparisons between trained and untrained limbs, 17 favored the trained side and 20 favored the untrained side, with the pooled effect landing at essentially zero.1Human Movement. A proposed model to test the hypothesis of exercise-induced localized fat reduction (spot reduction), including a systematic review with meta-analysis When results scatter randomly around no effect, the honest conclusion is that spot reduction, as most people imagine it, does not reliably happen.
There is a small caveat. Research has found that blood flow and the rate at which fat cells release their stored energy are somewhat higher in fat tissue sitting next to working muscles than next to resting muscles.4PubMed Central. Effect of an Endurance and Strength Mixed Circuit Training on Regional Fat Thickness: The Quest for the “Spot Reduction” One trial using prolonged abdominal aerobic endurance exercise found that trunk fat mass decreased about 3% more in the abdominal-exercise group compared to a treadmill-only control group, even though total fat loss was similar between the groups.5PubMed Central. Abdominal aerobic endurance exercise reveals spot reduction exists: A randomized controlled trial That is a real but tiny effect, and it required extended aerobic-type abdominal exercise, not standard sets of crunches or leg raises. Think sustained trunk rotations paired with cardio, not three sets of 15 reps and then moving on to another exercise.
The practical takeaway is that even if a small spot-lipolysis effect exists, it is dwarfed by the fat you lose through overall energy balance. Doing hundreds of leg raises will not visibly flatten your belly if the rest of your day does not create the energy deficit needed for total body fat loss.
The Two Kinds of Belly Fat and Why They Matter
Your abdomen stores fat in two distinct compartments, and they behave differently. Subcutaneous fat sits just below the skin, the stuff you can pinch. Visceral fat wraps around your internal organs deeper inside the abdominal cavity. Visceral fat cells are more metabolically active, more responsive to fat-releasing signals, and more resistant to insulin than subcutaneous fat cells.6PubMed. Subcutaneous and visceral adipose tissue: structural and functional differences This matters because visceral fat is the type more strongly linked to cardiovascular and metabolic health risks, and it is also the type that tends to respond faster to exercise and dietary changes.
Animal research demonstrates this nicely: genes involved in fat breakdown are upregulated several-fold in visceral fat during caloric restriction, while subcutaneous fat barely budges in gene expression.7PubMed. Visceral fat: higher responsiveness of fat mass and gene expression to calorie restriction than subcutaneous fat In humans, the pattern tracks. A systematic review of exercise interventions in overweight adults found that aerobic exercise of moderate or high intensity reduced visceral fat significantly, even without dietary changes, with reductions of over 30 square centimeters in women and over 40 square centimeters in men visible on CT scans after as little as 12 weeks.8PubMed Central. The Effect of Exercise on Visceral Adipose Tissue in Overweight Adults: A Systematic Review and Meta-Analysis
Here is the catch for leg-raise enthusiasts: the exercises that drive visceral fat loss in these studies are aerobic and whole-body in nature. Running, cycling, rowing, brisk walking. Resistance training, by contrast, showed no significant pooled effect on visceral fat in a separate meta-analysis comparing aerobic to resistance exercise.9PubMed. A systematic review and meta-analysis of the effect of aerobic vs. resistance exercise training on visceral fat Leg raises fall closer to the resistance-exercise side of the spectrum. They load muscles against gravity, but they do not elevate your heart rate the way sustained cardio does. If visceral fat loss is the priority, cardio earns its keep in a way that isolated ab work simply cannot.
What Actually Reduces Belly Fat
Fat loss, whether from the belly or anywhere else, comes down to burning more energy than you take in over a sustained period. The body draws on stored fat to make up the difference, and where it pulls from first is largely determined by genetics, sex hormones, and individual biology rather than by which muscles you exercise.
A well-known randomized trial (the CALERIE study) compared a 25% energy deficit achieved by diet alone versus the same deficit achieved through a combination of diet and exercise. Both groups lost roughly 10% of body weight, about 24% of their fat mass, and about 27% of their abdominal visceral fat. The distribution of fat lost was not altered by whether the deficit came from eating less or moving more.10PubMed Central. Effect of calorie restriction with or without exercise on body composition and fat distribution A companion analysis of the same cohort confirmed that visceral fat dropped about 25% in both groups, with no significant difference between them, though the diet-plus-exercise group did see meaningful improvements in blood pressure, cholesterol, and insulin sensitivity that the diet-only group did not.11PubMed Central. Caloric Restriction with or without Exercise: The Fitness vs. Fatness Debate
The message is straightforward: the caloric deficit is what drives the fat off. Exercise amplifies the health benefits and helps protect muscle, but it does not redirect where the fat comes from.
Does Exercise Intensity Matter for Belly Fat?
You might wonder whether high-intensity interval training (HIIT) has a special ability to target belly fat. Meta-analyses suggest both HIIT and moderate-intensity continuous training reduce whole-body fat mass and waist circumference similarly, with no significant difference between the two approaches for body composition. HIIT does, however, achieve comparable fat loss in roughly 40% less training time, which is a practical advantage for people short on schedule.12PubMed. The effects of high-intensity interval training vs. moderate-intensity continuous training on body composition in overweight and obese adults: a systematic review and meta-analysis A more recent review confirmed no difference between HIIT and continuous aerobic training for body fat percentage or abdominal visceral fat.13PubMed Central. High-intensity interval training is not superior to continuous aerobic training in reducing body fat: A systematic review and meta-analysis of randomized clinical trials
One exception worth noting: in obese women, very high-intensity interval protocols (at or above 90% of peak oxygen consumption) reduced visceral fat significantly more than moderate-intensity continuous training in one trial, with the HIIT group losing more than 15 square centimeters of abdominal visceral fat compared to less than 3.5 square centimeters in the moderate-intensity group.14PubMed. Exercise training-induced visceral fat loss in obese women: The role of training intensity and modality But this level of intensity is hard to sustain safely without a training base, and other meta-analyses have not found this advantage to be consistent across populations. The safest conclusion is that the best cardio intensity for belly fat loss is whichever one you will actually do consistently.
Resistance Training and Muscle Preservation
Where resistance exercises like leg raises do have a genuine role is in preserving or building lean mass during weight loss. When you eat in a caloric deficit, the body loses some muscle along with fat. Resistance training substantially offsets that loss. A trial in premenopausal women found that adding a supervised resistance training program to a controlled diet produced the steepest decrease in fat mass, and only the resistance-training-only group saw a significant increase in lean mass.15International Journal of Sport Nutrition and Exercise Metabolism. Resistance Training Combined With Diet Decreases Body Fat While Preserving Lean Mass Independent of Resting Metabolic Rate: A Randomized Trial Reviews of the broader literature agree that resistance exercise and adequate protein intake are central to maintaining muscle during weight loss.16PubMed Central. Preserving Healthy Muscle during Weight Loss
More muscle mass at the same body weight gives you a leaner appearance, including around the midsection. If you lose 10 pounds of fat but also lose 3 pounds of muscle, your belly may look less different than you hoped. If you preserve that muscle through resistance training, the same 10 pounds of fat loss produces a noticeably more defined torso. Leg raises contribute to this by strengthening the abdominal wall, even if they do not selectively melt the fat on top of it.
How Sex and Genetics Steer Fat Storage
Where your body prefers to store fat is not something you control through exercise selection. Testosterone promotes fat breakdown, suppresses fat accumulation, and limits the activity of enzymes that store fat in tissue. Lower testosterone in men is associated with increases in total fat, particularly subcutaneous fat. Estrogen, on the other hand, promotes the proliferation of new fat-storing cells and tends to direct fat storage toward the hips and thighs rather than the abdomen.17British Journal of Nutrition. Sex differences in fat storage, fat metabolism, and the health risks from obesity: possible evolutionary origins
This is why men tend to accumulate fat centrally (the “apple” pattern) while premenopausal women store it peripherally (the “pear” pattern). After menopause, as estrogen declines, women’s fat distribution shifts toward the abdominal pattern. No amount of targeted core work overrides this hormonal programming. It also explains why two people following the same training and diet plan can lose similar amounts of total fat but look different afterward: one person’s belly shrinks first, another’s thighs do.
Genetics layer on top of hormones. Twin studies have repeatedly shown that body fat distribution has a strong heritable component. If your parents carried weight around the middle, you are more likely to as well, and that fat will be among the last to go when you diet down. Frustrating, but knowing this helps set realistic expectations: the belly is often the first place fat accumulates and the last place it leaves, especially in men and postmenopausal women.
How Belly Fat Is Measured and Why That Matters
If you are tracking progress by looking in the mirror or pinching your skin, you might underestimate how much fat you have already lost. Subcutaneous abdominal fat is notoriously difficult to measure accurately with simple tools. Skinfold calipers miss a deep layer of subcutaneous fat beneath a fibrous sheet called Scarpa’s fascia, which means they undercount abdominal fat compared to imaging methods like MRI or CT.18Scientific Reports. Measurement of subcutaneous fat tissue: reliability and comparison of caliper and ultrasound via systematic body mapping Ultrasound can match MRI for two-dimensional fat thickness, but earlier comparisons against CT found large variability in ultrasound measurements at abdominal sites.19PubMed. Accuracy of subcutaneous fat measurement: comparison of skinfold calipers, ultrasound, and computed tomography
For most people, waist circumference measured with a tape measure at the same spot each time is a more practical and reliable way to track abdominal fat changes than trying to pinch your belly. Even then, changes in visceral fat, the type most important for health, are invisible to any surface measurement. You can lose a meaningful amount of visceral fat and feel healthier without your waist tape reading budging much, because the deep fat shrank while the superficial fat stayed put for a while longer. If the scale, the tape, and the mirror are all moving slowly but your energy, blood pressure, or bloodwork are improving, you are likely losing the more dangerous fat first.
Protecting Your Back During Leg Raises
Because the hip flexors, particularly the psoas, attach directly to the lumbar spine, leg raises can aggravate lower back pain if performed incorrectly. When the abdominal muscles are too weak to stabilize the pelvis, the leg-raising motion pulls the lower back into an exaggerated arch (anterior pelvic tilt), compressing the lumbar vertebrae. A case study found that modifying the leg raise by adding neck flexion helped activate the abdominal muscles enough to fix the pelvis and prevent trunk movement, reducing pain and improving pelvic posture.20PubMed Central. Effect of modified leg-raising exercise on the pain and pelvic angle of a patient with back pain and excessive lordosis
A few practical modifications reduce the risk:
- Press your lower back flat: Before lifting your legs, push your lumbar spine into the floor and maintain that contact throughout the set. If your lower back arches off the ground, your abs have lost the stabilization battle.
- Bend your knees: Bent-knee raises shorten the lever arm and reduce the load on the hip flexors and spine. Work up to straight-leg versions as your core strength improves.
- Stop before failure: The last few reps, when form breaks down, are when the lower back takes over. Ending the set with clean form is worth more than grinding out extra reps with a hyperextended spine.
These adjustments make leg raises safer and actually increase abdominal muscle involvement, getting you more of the benefit the exercise is supposed to provide in the first place.
The Hormonal Side of Exercise-Induced Fat Breakdown
When you exercise, your body mobilizes stored fat for fuel through a hormonal cascade. The sympathetic nervous system and catecholamines (adrenaline and noradrenaline) are the main drivers of fat release during physical activity.21PubMed. Interactions of metabolic hormones, adipose tissue and exercise Atrial natriuretic peptide and insulin also play key roles, with insulin suppression during exercise allowing fat cells to release their contents more freely.22PubMed Central. Influence of Acute and Chronic Exercise on Abdominal Fat Lipolysis: An Update
These hormones travel through the bloodstream and act on fat cells throughout the body, not just near the muscles being used. That is the fundamental reason spot reduction does not work the way people hope: the signal to release fat is systemic, not local. Your body decides which fat stores to tap based on receptor density, blood flow, and hormonal sensitivity in each depot, not based on which muscles you are flexing. Visceral fat cells, with their higher density of receptors for catecholamines, tend to respond earlier and more aggressively to these circulating signals, which is part of why aerobic exercise is effective at trimming the deep belly fat even when the exercises involve your legs, arms, and everything else.
Low- and moderate-intensity exercise triggers hormonal changes that favor fat release. Very high intensity shifts the fuel mix toward carbohydrate. But over a 24-hour period, total energy expenditure matters far more than the fuel mix during any single workout. A session that burns more carbohydrate during exercise tends to burn more fat during recovery, and vice versa, so the net effect on body fat over days and weeks comes back to the total energy balance.
Where Leg Raises Fit in a Practical Routine
None of this means you should drop leg raises from your training. They build the kind of core stiffness that protects your spine during heavy lifts, improves posture, and supports athletic movements from sprinting to throwing. Stronger abdominal muscles also give the midsection a more toned appearance once the overlying fat is reduced, which is, after all, why most people want a flat belly in the first place.
Think of leg raises as one piece of a three-part strategy. First, create a moderate caloric deficit through diet, because that is the non-negotiable driver of fat loss. Second, include regular aerobic exercise, whether it is jogging, cycling, swimming, or brisk walking, because that is the type of exercise with the strongest evidence for visceral fat reduction. Third, add resistance training, including core work like leg raises, to maintain or build muscle so that the body you reveal as the fat comes off actually looks the way you want it to. Combining time-restricted eating or caloric restriction with both aerobic and resistance exercise has been shown to reduce fat mass while increasing lean mass in overweight adults.23PubMed Central. Time-restricted eating and concurrent exercise training reduces fat mass and increases lean mass in overweight and obese adults
In younger populations, a meta-analysis of exercise interventions found that aerobic exercise significantly reduced visceral fat, while resistance exercise alone did not reach statistical significance for visceral fat reduction.24Frontiers in Physiology. Effects of different exercise types on visceral fat in young individuals with obesity aged 6–24 years old: A systematic review and meta-analysis That does not make resistance training unimportant. It means that if your time is limited and belly fat is the target, prioritizing cardio over isolated core exercises gives you more return on investment. Leg raises take two minutes of a workout. A 30-minute run burns vastly more energy and triggers a far larger systemic hormonal response. Do both, but do not mistake one for the other in terms of what drives the fat off.