The growth of the gluteal region, defined by bone structure and soft tissue accumulation, is a major component of physical maturity. Body shape undergoes its most significant changes during adolescence, driven by a surge in sex hormones. Determining when the buttocks stop growing is tied directly to the final stages of puberty and the stabilization of the endocrine system.
The Developmental Timeline
Developmental growth ceases when the body reaches full physical maturity, typically concluding in the late teens to early twenties (18 to 25 years). The soft tissue growth in the gluteal region is closely linked to the final stages of a person’s pubertal timeline.
The most rapid phase of growth occurs during early and mid-puberty. The pelvis widens, establishing the skeletal frame for the gluteal region. The filling out of the hips, thighs, and buttocks with fat is a characteristic physical milestone of later puberty.
This developmental process is highly individualized, meaning the specific age of completion varies significantly. Genetics, overall health, and the timing of puberty onset influence when the final shape is established. While structural changes are largely complete by the late teens, soft tissue redistribution can continue into the early twenties.
Hormonal Drivers of Gluteal Shape
The mechanism behind this developmental change is a direct result of endocrine signaling, primarily the role of sex hormones. For individuals assigned female at birth, increased circulating estrogen signals the body to store fat preferentially in the lower body. This directed fat storage, known as the gluteofemoral distribution, is responsible for the characteristic shape of the hips, thighs, and buttocks.
Estrogen promotes the formation and enlargement of subcutaneous adipose tissue in this region. This localized fat accumulation stores energy reserves necessary for potential pregnancy and lactation. When estrogen levels stabilize after puberty, this redistribution process ends.
In contrast, rising testosterone levels in individuals assigned male at birth promote greater lean muscle mass and direct fat storage toward the visceral (abdominal) area. This difference creates distinct sex-specific patterns of fat distribution. Gluteal developmental growth ceases when sex hormone levels reach their adult, stable baseline.
Genetics, Muscle, and Adult Changes
While developmental growth stops in early adulthood, the size and shape of the gluteal region remain dynamic throughout life. Genetics play a fundamental role, determining the potential for fat storage and the underlying skeletal structure of the pelvis and femur. The inherited genetic blueprint sets the limits for fat deposition.
Changes to gluteal size and shape can still occur at any age through muscle hypertrophy—the enlargement of the gluteal muscles (maximus, medius, and minimus) via resistance exercise. This change is independent of the developmental clock. Building muscle mass can dramatically alter the contour and firmness of the area.
Fluctuations in size and shape also continue due to changes in diet and overall weight. Significant weight gain or loss, pregnancy, and aging can alter the appearance of the buttocks long after development has ceased. Declining estrogen levels after menopause, for instance, can cause a shift in fat distribution away from the gluteofemoral region toward the abdomen.