Normal, not a disease
Reviews estimate that 80% to 90% of women have cellulite after puberty (some say up to 98%), but that's an estimate, not a survey: "Very little is known about the prevalence and incidence of cellulite". In 184 girls aged 12 to 18 in São Paulo, 77.7% had it, and 39.7% said it affected their quality of life. A review calls it "not a pathologic condition", and the first paper to grade it wrote of "the essential normality and inevitability of it in women". About 2% of men have it, usually with low male hormones or on hormone treatment.
Sources 1, 2, 3, 4, 20
The bands under the skin
Fat under the skin sits in pockets held by fibrous bands that tie the skin to deeper layers. On scans of 30 women, "Fibrous septa were visualized in 96.7% of the area with cellulite depressions". In 20 body donors, men had more bands tying fat to the skin, and men's bands took more force to break (38.46 against 23.26 newtons). Where the bands hold the skin down and fat pushes up between them, the skin dimples.
Sources 21, 22
Not toxins, water or poor circulation
In women with cellulite, scans "did not confirm the hypothesis of increased water content" in the fat, and in 7 people, blood flow and fat breakdown were the same in dimpled and smooth skin.
Sources 23, 24
Hormones, age and genes
Oestrogen likely plays a big part, and pregnancy, breastfeeding, the pill and hormone replacement therapy (HRT) may make cellulite more visible. Thinner skin with age isn't the main cause, since young women commonly have it. A small study of 200 lean women with cellulite found two possible genes, a finding that hasn't been repeated.
Sources 1, 2, 25
Body fat matters, but lean women have it too
In 72 people scanned in 3D, severity tracked the percentage of fat on the thigh. But lean and fit women have it too: "Most women, even very fit women, have cellulite". And "During weight gain, the septal network does stretch but does not shrink from weight loss."
Sources 26, 25, 27, 1
Why poses, light and photos change how it looks
Doctors check cellulite standing, because "In the prone position, there is less tension on the fibrous septa and the dimples tend to disappear." Trials grade photos on scales such as the Cellulite Severity Scale (5 features, each scored 0 to 3), and a review stresses that camera settings, lighting and position must be the same each time. A before-and-after photo after a yoga programme is a weak test.
Sources 1, 28, 29
Muscle under the skin
Cellulite sits in the fat and bands above the muscle. Building the muscle underneath may change how the area looks, which is the American Academy of Dermatology's reasoning, but no trial has measured it, and the one blinded trial of glute strengthening found no change.
Sources 27, 6
Cellulite isn't cellulitis, and it isn't lipoedema
Cellulitis is an infection of the deeper skin: "Cellulitis makes your skin painful, hot and swollen." Lipoedema is a build-up of fat in both legs and sometimes the arms, with pain, tenderness or heaviness and easy bruising, and "It's not caused by being overweight". A dermatology review says lipoedema "has often been misclassified as a severe or atypical variant of cellulite", and "Unlike lipedema, cellulite is typically painless."
Sources 16, 18, 30
How this guide splits with its neighbours
Our fascia and cellulite guide covers cellulite in depth (fascia blasting, rolling, massage and the layers); our Pilates for cellulite guide covers Pilates; our how to lose thigh fat guide covers thigh fat and exercise in general; and our yoga for lipoedema guide covers lipoedema.