You’re rubbing your arm or maybe your thigh, and suddenly, you feel it. A small, rubbery knot. Maybe it slides around under your fingertips like a marble, or perhaps it feels more like a soft, squishy grape. It’s unsettling. Your brain immediately goes to the worst-case scenario because that’s what brains do when they find something that isn't supposed to be there. But honestly? Most of the time, when fat feels lumpy under skin, it’s just your body being a little bit weird with how it stores adipose tissue.
Bodies aren't smooth, uniform blocks of clay. They're messy. Underneath your epidermis and dermis lies the subcutaneous fat layer, and this layer is rarely a perfect sheet of yellow butter. It’s organized into lobules, held together by connective tissue called septa. Sometimes those lobules get crowded. Sometimes the "packaging" of the fat gets snagged. This results in texture.
The Most Likely Culprit: The Lipoma
If you have a lump that feels doughy and moves easily when you poke it, you’re probably looking at a lipoma. These are incredibly common. Doctors see them every single day. A lipoma is basically a slow-growing tumor made of fat cells, but don't let the word "tumor" freak you out. They are benign. They aren't cancer.
According to the Cleveland Clinic, about 1 in every 1,000 people will develop a lipoma at some point. They usually show up in middle age, though they can pop up whenever they feel like it. You’ll mostly find them on the shoulders, neck, back, or arms. They usually stay small—under two inches—but occasionally they decide to go big. There’s even a condition called Dercum’s Disease (adiposis dolorosa) where people grow multiple painful lipomas, but that is quite rare. For the average person, it’s just a harmless, annoying bump.
Why does it feel "Grainy" or "Pebbly"?
Sometimes it’s not one big lump. Sometimes it feels like a bag of tiny pebbles. This is often just the natural architecture of your fat. If you lose a significant amount of weight, the underlying structure of your fat lobules can become more apparent.
Think of it like a quilt. When the quilt is stuffed full, it looks smooth. When the stuffing thins out, you start to feel the individual tufts and the stitching. This is especially true in areas like the outer thighs or the abdomen. Cellulite is essentially this exact phenomenon—fat pushing through the connective tissue bands, creating a dimpled or lumpy texture. It’s not a medical "condition." It’s just how skin and fat interact.
Fat Necrosis: The Lumpy Aftermath of Injury
Here is something people often miss. If you’ve had a "seatbelt injury" from a car accident, or maybe you tripped and hit your hip hard against a table, you might find a firm lump weeks later. This is called fat necrosis.
When fat cells get damaged by trauma, they can die. The body then tries to replace that damaged tissue with firm scar tissue, or the fat cells might release their contents, forming a small cyst. These lumps can feel quite hard—harder than a lipoma—which makes them more frightening. In the breast tissue, fat necrosis is a very common cause of lumps that end up being totally harmless, though they usually require an ultrasound just to be safe.
When the Lumps are Dercum’s or Panniculitis
We have to talk about the more complex stuff, too. Inflammation is a beast. Panniculitis is a group of conditions where the fat layer itself becomes inflamed. It’s not just "fat feels lumpy under skin" at that point; it’s usually red, tender, and sometimes accompanied by a fever.
Then there’s the genetic side of things. If you have dozens of these lumps, you might have Familial Multiple Lipomatosis. It’s exactly what it sounds like. Your DNA basically has a blueprint that says "make more fat knots." While it's a pain for aesthetics, it generally doesn't impact your internal health.
Is it a Cyst or a Lipoma?
It is very easy to mix these up. A sebaceous cyst is a sac filled with keratin (a cheesy-smelling protein, if you’re brave enough to pop it—which you shouldn't). Cysts are usually closer to the surface of the skin than lipomas.
- Lipomas: Deeper, softer, move easily under the skin.
- Cysts: Often have a tiny "punctum" or hole in the center, feel a bit firmer, and are attached to the skin itself.
- Fibromas: These are made of connective tissue. They feel much harder, like a pea or a pebble that won't give when you squeeze it.
The "Danger" Check: When to see a Doctor
I'm an expert writer, not your personal physician. You should always get a new lump checked out. It's the only way to get real peace of mind. However, there are specific "red flags" that doctors look for.
- Rapid Growth: If that little marble becomes a golf ball in two months, go in.
- Immobility: If the lump is "fixed" and won't budge when you try to wiggle it, that’s a sign it might be attached to deeper muscle or bone.
- Pain: Lipomas usually don't hurt unless they're pressing on a nerve. If it's throbbing or sharp, get it looked at.
- Hardness: If it feels like a rock rather than a piece of dough.
There is a very rare type of cancer called liposarcoma. It sounds like lipoma, but it’s the malignant version. It usually occurs deep in the thigh or the abdomen, not just under the skin of your arm. It's rare—only about 2,000 cases a year in the U.S.—but it’s the reason doctors take "fixed, hard lumps" so seriously.
Can you get rid of them?
If the fat feels lumpy under skin and it’s bothering you, you have options. But honestly, most doctors will tell you to leave them alone if they aren't hurting.
Surgery is the most common fix. A surgeon makes a small nick, "pops" the lipoma out (it usually comes out like a slippery little bean), and stitches you up. There’s also liposuction, where they suck the fat out through a needle, though this has a higher chance of the lump coming back because the "capsule" of the lipoma might be left behind.
Don't bother with creams or "fat-dissolving" supplements you see on TikTok. They don't work for localized fat lumps. The lump is contained in a fibrous capsule; no amount of rubbing green tea extract on your skin is going to melt it away.
Modern Diagnostic Tools
In 2026, we have incredible imaging. If you’re worried, a doctor will likely order a high-resolution ultrasound. It’s non-invasive and can quickly differentiate between a fluid-filled cyst, a solid lipoma, and a vascular growth. If the ultrasound is "equivocal" (fancy doctor talk for "we aren't 100% sure"), they might move to an MRI or a fine-needle aspiration.
🔗 Read more: How Do I Get Smaller Hips: The Reality of Bone Structure vs Body Fat
Aspiration involves sticking a tiny needle in, grabbing a few cells, and looking at them under a microscope. It takes five minutes. It’s a bit of a pinch, but it beats a week of worrying.
Actionable Next Steps for Your Lumpy Skin
Stop poking it. Seriously. If you constantly squeeze and prod a lipoma or a pocket of fat, you can cause localized inflammation, which makes the area swell and feel even bigger than it actually is. You’re essentially bruising the fat.
Do a "Lump Inventory"
Check the rest of your body. Do you have others? Often, people find one, freak out, and then realize they’ve actually had three others on their ribcage for a decade and just never noticed. Knowing you have multiple "stable" lumps is actually a good sign—it usually points toward a benign genetic tendency.
Track the Size
Take a photo of the area with a ruler next to it. Check it again in four weeks. If it hasn't changed, you can breathe a little easier while you wait for your appointment.
Check your Family History
Ask your parents or siblings if they have "fatty bumps." If your dad has five of them on his forearms, you likely just inherited his "lumpy fat" genes. It’s more common than you’d think.
Schedule a Dermatology Consult
Skip the general practitioner if your insurance allows and go straight to a dermatologist. They spend all day, every day, looking at skin and subcutaneous tissue. They can often tell what a lump is just by feeling it for three seconds.
The reality is that our bodies are imperfect. As we age, the tissue under our skin shifts, scars, and clumps. If your fat feels lumpy under skin, it’s usually just a sign of a body that’s been through some life. Get it checked to be safe, then stop worrying and get back to your day.
Summary of Actionable Insights:
- Self-Monitor: Use the "Rule of 5cms"—lumps smaller than a lime that are soft and movable are rarely urgent.
- Document: Record the date you found it and its current size to track growth.
- Professional Review: Ensure any lump that is hard, fixed, or growing rapidly is biopsied or imaged via ultrasound.
- Avoid Irritation: Refrain from aggressive massage or "home popping," which can lead to infection or internal scarring.