Why Do I Have a Dent in My Lower Stomach?

A visible dent or indentation in the lower abdomen usually traces back to one of a handful of causes, ranging from completely normal anatomy to post-surgical scarring to changes in the fat layer beneath the skin. The lower stomach sits at a crossroads of muscle, connective tissue, and fat distribution that makes it particularly prone to contour irregularities. Figuring out what is behind yours depends on where exactly the dent is, how it appeared, and what your body has been through recently.

Normal Anatomy That Can Look Like a Dent

Your abdominal wall is not one smooth slab of muscle. It is crisscrossed by bands of tough connective tissue that create natural grooves. The most prominent is the linea alba, a fibrous strip running vertically down the center of your abdomen from the breastbone to the pubic bone. This structure is made up of multiple interwoven layers of fibers running in different directions, including transverse fibers that make up close to half the total and oblique fibers arranged in a “scissors-like” pattern on the front surface.¹ Along the sides of the rectus muscles, another band called the linea semilunaris creates a curved groove, and horizontal tendinous intersections divide each rectus muscle into segments.²

When body fat is low enough, these grooves show up as the familiar “six-pack” or “eight-pack” appearance. But at moderate body fat levels, only some of these landmarks may be visible, and the lower abdomen is often where you see them last or in incomplete form. If you have a single horizontal crease or shallow dent across the lower stomach, you might simply be seeing one of these tendinous intersections or the inferior edge of the rectus muscle where it attaches to the pubic bone. These grooves vary a lot from person to person in depth and exact placement.

Diastasis Recti and the Midline Bulge-Dent Combination

Diastasis recti is a separation of the two halves of the rectus abdominis muscle along the midline. It creates a characteristic pattern where the central abdomen bulges outward when you engage your core, and at rest, the area between the separated muscles can appear sunken or indented relative to the muscle edges on either side. This condition affects many people, but it is most strongly associated with pregnancy and is diagnosed based on the gap between the paired rectus muscles.³ If you can lie on your back, lift your head slightly, and feel a soft gap wider than a finger or two running vertically above or below your belly button, diastasis recti is a strong possibility.

A physical exam can diagnose most cases, though classification systems have been developed that account for the width of the separation and its location along the midline to help guide treatment decisions.⁴ When there is any doubt or when a hernia needs to be ruled out, ultrasound is typically the first imaging step. Ultrasound is considered the go-to tool for evaluating abdominal wall issues because it is fast, inexpensive, and does not involve radiation.⁵

For postpartum diastasis recti, targeted exercise programs have shown promising results. Approaches that combine deep core muscle work, pelvic floor exercises, breathing techniques, and functional movements can reduce the gap between the separated muscles and improve related symptoms.⁶ One thing to be aware of, though, is that certain exercises can temporarily widen the gap below the belly button. Pelvic floor contractions and deep abdominal “drawing-in” movements were found to increase the separation in the sub-umbilical area even while not worsening it above the belly button.⁷ This does not mean those exercises are harmful long term, but it does suggest that rehab for lower abdominal diastasis recti deserves some nuance and ideally guidance from someone who specializes in it.

Post-Surgical Scars and the C-Section “Shelf”

If you have had abdominal surgery, a dent or crease below or at the incision line is extremely common. Cesarean sections are probably the most frequent culprit. The horizontal incision sits low on the abdomen, typically just above the pubic hairline. As the wound heals, scar tissue forms underneath the skin and can tether to the deeper tissue layers. Over time, this fibrosis and tissue contraction above and below the healing gap creates a persistent contour deformity, sometimes called a cesarean “shelf” or “apron.”⁸ The tissue above the scar can overhang the indented scar line, creating a visible ledge or dent that persists even with weight loss or exercise.

This scar-tethering effect is not unique to cesarean sections. Appendectomy scars, laparoscopic port sites, and hernia repairs can all produce localized indentations where scar tissue binds the skin down to the muscle layer beneath it. The lower abdomen is especially susceptible because fat deposits in this region tend to be thicker, making any area where the skin is pulled inward more visually prominent.

Previous liposuction is another surgical cause worth considering. While modern techniques achieve high satisfaction rates, contour irregularities still occur. A retrospective study of nearly 200 patients found that about 9% developed minor contour irregularities after standard liposuction.⁹ These irregularities can show up as dents, divots, or uneven surfaces where fat was removed unevenly or where the skin contracted inconsistently during healing.

Localized Fat Loss from Repeated Pressure or Injections

Not all dents involve muscle or surgery. Sometimes the fat layer itself thins in a specific spot, leaving a visible depression. If you inject insulin or another medication into the same lower abdominal area repeatedly, you risk developing lipoatrophy at the injection site, which is a localized loss of the fat tissue under the skin. The result is a dent or hollow exactly where the needle goes in.¹⁰ This reaction is thought to be driven by an immune-mediated inflammatory process triggered by the injected substance.¹¹

Insulin-related lipoatrophy has become rarer since the switch to modern human insulin formulations, but it still occurs with insulin analogs. People who reuse the same needle or fail to rotate injection sites seem to be at higher risk.¹² The practical takeaway: if you inject anything regularly into your abdomen and notice a depression forming, rotate your injection sites and use a fresh needle each time.

A related condition, lipoatrophia semicircularis, causes band-like depressions in the skin, usually on the thighs but occasionally on the abdomen. It has been linked to repetitive pressure from tight clothing like constricting jeans or from leaning against hard-edged surfaces like desks.¹³ The mechanism is not entirely settled, but the combination of repeated minor trauma and environmental factors seems to damage the subcutaneous fat in a localized area. If you notice a horizontal, band-shaped dent across your lower abdomen that follows the line of a waistband, this is worth considering.

Weight Fluctuations and Excess Skin

Significant weight loss, whether gradual or after bariatric surgery, often leaves the lower abdomen with contour changes that can include visible dents, creases, and folds. Loose skin tends to settle under gravity, and when it folds over itself, the crease beneath the fold can look and feel like a dent. The abdomen is one of the most affected areas. In a study of post-bariatric surgery patients, excess abdominal skin caused the most discomfort of any body region in both men and women, and the abdomen was the site men most frequently reported as a problem area.¹⁴

Even without dramatic weight loss, gaining and losing moderate amounts of weight over the years can redistribute fat unevenly. The lower abdomen tends to be a stubborn fat-storage area, and when you lose fat from surrounding regions first, existing anatomical grooves and any scar tethering become more visible. Conversely, gaining weight can fill in dents that were previously visible. The lower stomach’s appearance is surprisingly dynamic, shifting with relatively small changes in body composition.

Connective Tissue and Hormonal Factors

Some people are structurally predisposed to abdominal contour irregularities because of how their connective tissue is built. Conditions involving joint hypermobility and tissue laxity can affect the abdominal wall as well. In Ehlers-Danlos syndrome, for instance, the connective tissue laxity that causes loose joints also weakens the ligaments supporting the abdominal organs, and in rare cases has been linked to internal organ displacement that can change the external abdominal contour.¹⁵ You do not need a full-blown connective tissue disorder for this to be relevant, though. People at the hypermobile end of the normal spectrum often have stretchier, thinner abdominal wall tissue that reveals underlying structures more readily.

Hormonal shifts also play a role in how the lower abdomen looks over time. After menopause, skin collagen declines at a rate of roughly 2% per year, skin thickness drops by about 1% per year, and skin elasticity decreases by about 1.5% per year.¹⁶ Over a decade or two, these changes add up considerably. Thinner, less elastic skin over the lower abdomen means that any underlying groove, separation, or scar becomes more pronounced. A dent that was barely noticeable at 40 can become quite visible at 60 without any new injury or change in weight.

When a Dent Signals Something That Needs Attention

Most lower abdominal dents are cosmetic concerns rather than medical emergencies. But certain features warrant a visit to your doctor. A dent that appeared suddenly, especially after straining or lifting, could indicate a hernia that has reduced, meaning a loop of intestine briefly pushed through a weak spot and then slid back, leaving a visible depression or soft area. Pain, tenderness, or swelling at the site of a dent are all reasons to get checked out. A dent accompanied by skin color changes, warmth, or progressive deepening over weeks should also be evaluated, as these can signal an underlying soft tissue problem.

Abdominal wall hernias can have a meaningful psychological impact beyond the physical symptoms. Research into the lived experiences of people with abdominal wall hernias identified three major themes related to mental health: emotional distress, disrupted sense of identity, and the need for coping strategies and support.¹⁷ If an abdominal dent is affecting how you feel about your body or limiting your activities, that is worth bringing up with a healthcare provider, even if the underlying cause turns out to be benign.

How to Figure Out Which Cause Applies to You

A process-of-elimination approach works well for most people. Start with the basics:

• Location: A midline vertical dent, especially visible when you contract your core, points toward the linea alba or diastasis recti. A horizontal crease below the belly button suggests a surgical scar, waistband pressure, or a skin fold from weight changes.
• History: Recent pregnancy, abdominal surgery, significant weight change, or regular abdominal injections each narrow the list considerably.
• Onset: A dent you have always had is likely anatomical. One that appeared over weeks to months after a specific event fits post-surgical or post-pregnancy changes. One that appeared suddenly needs a medical evaluation.
• Texture: If you can feel a gap between firm muscle edges when you press the dent, that suggests diastasis recti. If the skin feels tethered and does not lift freely, scar adhesion is likely. If the tissue just feels thin or hollow, localized fat loss is the more probable explanation.

Your doctor can confirm most of these causes with a physical exam alone. If there is any ambiguity, an ultrasound of the abdominal wall can distinguish between muscle separation, hernia, scar tethering, and fat layer changes without exposing you to radiation or requiring an expensive scan.

Improving the Appearance of a Lower Abdominal Dent

What you can do about the dent depends entirely on the cause. For diastasis recti, structured core rehabilitation is the first-line approach, with surgery reserved for cases that do not respond after months of consistent exercise. For scar tethering after a cesarean section or other surgery, scar massage and myofascial release techniques can sometimes free the adhesion between skin and deeper tissue, reducing the depth of the indentation. A physical therapist or dermatologist may also use tools like vacuum-assisted scar mobilization. In stubborn cases, a minor surgical revision can release the tethered tissue.

For dents caused by localized fat loss, options are more limited. Fat grafting, where fat is harvested from one area and injected into the depression, can restore contour. Injectable fillers are sometimes used for smaller defects. For lipoatrophy from insulin injections, switching to a different injection technique or medication formulation and rotating sites diligently tends to prevent worsening, though existing dents may not fully resolve on their own.

If excess skin after weight loss is the primary issue, non-surgical skin tightening treatments like radiofrequency or ultrasound devices produce modest improvements at best. Abdominoplasty remains the most effective option for significant excess skin, and it can address scar tethering and diastasis recti at the same time. That said, it is major surgery with real recovery time and risks, so it is a decision worth discussing thoroughly with a board-certified plastic surgeon rather than pursuing on impulse.

The Waistband Effect and Everyday Habits

One overlooked contributor to lower abdominal denting is chronic pressure from clothing. Tight waistbands, belts, and compression garments worn for long stretches can leave temporary or even semi-permanent indentations in the skin and subcutaneous fat. In most people, the mark fades within minutes to hours. But the condition lipoatrophia semicircularis shows that, in susceptible individuals, this kind of low-grade repetitive pressure can cause lasting changes in the fat layer. The cases linked to constricting jeans suggest that fashion choices can, over time, physically reshape the tissue contour of the lower abdomen.¹³

If you have noticed a horizontal dent that matches the line of your usual pants or belt, try switching to higher- or lower-waisted options for a few months and see if the dent softens. For most people it will, but if it does not, the fat layer change may have become structural rather than just a temporary compression mark. There is no established treatment that reliably reverses lipoatrophia semicircularis, though removing the source of pressure typically prevents it from getting worse.