The inward curve is a gap between two bones

Run a hand down the side of the body from the waist. There is a bony ridge at the top of the pelvis, and lower down there is another bony prominence at the top of the thigh bone. Between those two points the skeleton steps inward. Muscle and fat drape across the gap, and where the drape is thin, the surface follows the step and produces the indentation people call a hip dip.

That is the whole mechanism, and it explains nearly every confusing thing about the subject. The distance between those two landmarks is set by skeletal proportion. It does not respond to diet, it does not respond to training, and it is not a sign that anything has gone wrong.

It also explains why the feature is so often more obvious in lean, athletic people. Less soft tissue covers the gap, so more of the underlying shape shows through. Losing weight in pursuit of a smoother line frequently produces a sharper one.

What hip dips are not

Three other concerns get confused with this one, and each has a different answer, so the distinction is worth making carefully.

They are not saddlebags. Saddlebags are an excess of fat on the outer thigh, sitting below the dip. That is a surplus, and it is commonly treated by removing fat. Hip dips are a shortage in the region above. The two can appear in the same person, and when they do, the saddlebag makes the dip look deeper by contrast. Treating one without recognizing the other is how people end up disappointed by a technically successful operation.

They are not a flat or low-projecting buttock. That is a question about projection from behind rather than contour from the side, and it is what buttock augmentation is aimed at. The procedures overlap in technique and are frequently discussed together, but the goals are different and so is the placement.

They are not loose skin. Skin laxity across the outer thigh and hip, most often after significant weight loss, is excess tissue rather than absent tissue, and it is addressed by removing and tightening skin. A thigh lift treats that problem. Adding volume under lax skin does not fix laxity, and tightening skin over a skeletal gap does not fill it.

Why the usual advice underperforms

The most common recommendation is targeted exercise. Strengthening the gluteus medius, which sits over the upper part of this region, can add a modest amount of contour, and there is nothing wrong with the training itself. What it cannot do is move the pelvis further from the femur. When a program promises to erase the indentation, it is promising a change in skeletal proportion.

The second common recommendation is fat loss, on the assumption that the dip is a fat deposit. It is the opposite. Reducing overall body fat thins the layer that was softening the transition, and the contour usually becomes more defined.

The third is liposuction, and this is the one that carries real consequences. Removing fat from the indentation deepens it. The reason the idea spreads is that the neighboring areas genuinely are treated with liposuction, and the assumption travels a few inches across the body without anyone checking whether it still holds.

What does change the contour

Only adding volume addresses the shape directly, and in practice that means the patient's own fat. Fat is harvested from an area where it is not wanted, processed, and placed in the soft tissue overlying the gap. Because the fat comes from the patient, the harvest and the correction are usually planned as one operation, which is why this is discussed alongside fat transfer and, when the buttock is also being addressed, alongside the comparison with implants.

Three limits are worth stating plainly before anyone books a consultation.

Donor fat has to exist. A patient who is lean everywhere may not have enough to harvest. Since a proportion of transferred fat does not survive, the amount placed must exceed the amount meant to remain, which raises the requirement again. The people in whom hip dips are most visible are frequently the people with the least material available to correct them.

Survival is partial and not fully predictable. Some of the graft establishes a blood supply and stays. Some does not. Results settle over months rather than appearing finished, and a second session is sometimes part of the plan rather than a sign that something failed.

The skeleton is still there. Volume softens the step between the two bony landmarks. It does not remove it. A surgeon describing a result as complete erasure of the anatomy is describing something the technique does not do.

Fat grafting in the hip and buttock region also carries a specific safety discussion about the plane in which fat is placed, which is the single most important technical question in this class of operation and belongs in a conversation with a board-certified plastic surgeon rather than in an article.

How the decision usually goes

The useful examination is not complicated. It establishes where the bony landmarks sit, how deep the gap between them is, how much soft tissue currently covers it, and whether the outer thigh below is contributing excess that exaggerates the appearance. It also establishes whether enough donor fat exists to do anything meaningful.

Those four findings decide the answer, and one of the possible answers is that the contour is a feature of the patient's skeleton, that no proportionate operation will change it much, and that they should keep their money. That conclusion is more common than the volume of content on this topic would suggest, and a patient who hears it has been given something useful.

For patients whose concern is really the overall silhouette rather than the indentation specifically, the more productive conversation is often about body contouring as a whole, where the waist, the flank and the outer thigh are considered together rather than one feature being isolated and treated as a defect.

Find out whether yours can be changed

The examination that separates a skeletal contour from a soft tissue one takes minutes, and it determines whether fat transfer is worth considering or whether the honest answer is that it is not.

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Exercise can change the muscle around the area but it cannot change the skeleton underneath it, and the skeleton is what creates the shape. The indentation sits between the top of the pelvis and the top of the thigh bone, and how far apart those two landmarks sit is fixed. Building the gluteus medius can add a small amount of contour above the dip, and losing body fat generally makes the dip more visible rather than less, because there is less soft tissue to soften the transition. Programs sold as hip dip workouts are not dishonest about the exercises themselves, only about what the exercises are able to reach.
They are normal and extremely common, and they are not a sign of being overweight or of being out of shape. They are frequently more pronounced in lean and athletic people for the simple reason that less subcutaneous fat lies over the gap. A patient who is told that hip dips indicate a problem with their fitness or their diet has been told something that is not true. Whether the contour is worth treating is a question about preference and proportion, not about health.
Liposuction removes fat and hip dips are a deficit of volume, so liposuction in the area itself tends to deepen the indentation rather than correct it. This is the most consequential misunderstanding about the topic, because the surrounding regions are commonly treated with liposuction and the assumption carries across. Liposuction of the flanks or outer thighs can change how the whole silhouette reads and may make the transition look smoother, but it is working on the areas around the dip, not on the dip.
Adding volume to the lateral hip is the only approach that addresses the contour directly, and in practice that means transferring the patient's own fat. Fat is harvested by liposuction from somewhere it is not wanted, processed, and placed into the soft tissue over the indentation. The result depends on how much donor fat is available, how much of the transferred fat survives, and how deep the underlying skeletal gap is. It softens the transition rather than eliminating the anatomy.
Often not, and this is worth knowing before a consultation rather than during one. Fat transfer requires donor fat, and a patient who is lean everywhere may not have enough to harvest for a meaningful correction. Not all transferred fat survives, so the volume placed has to exceed the volume intended to remain, which raises the requirement further. A very thin patient is also the patient in whom the dip is most visible, which is the frustrating part of the arithmetic. An honest consultation sometimes ends with the conclusion that there is not enough material to work with.

Related reading: fat transfer for the technique itself, buttock augmentation when projection is the concern rather than the side contour, thigh lift for skin laxity across the outer thigh and hip, and body contouring for the whole silhouette.