What causes some people to have very uneven fat deposits?

December 6, 2007 9:10 AM

What causes some people to have very uneven fat deposits?

Every so often, I meet someone who carries their fat in a very uneven way -- often, they will be very large around the hips or butt and thin elsewhere, but sometimes the fat is higher or lower on their body. Often, they are quite slender overal, except for one area that can be extremely large.

Is there a general term for this condition?

What causes it? (ie, is it genetic, hormonal, environmental?)

posted by Forktine to health & fitness (15 comments total)

*overall*
posted by Forktine at 9:10 AM on December 6, 2007

One part of it can be usage.

For me, I have very muscular legs with almost no fat on them. I have tiny T-Rex arms, but a rather rotund mid-section.

It's because I spend at least 30 minutes a day biking or walking, very little time doing anything with my arms (except playing bass), and I rarely exercise my midsection, so the fat feels safe there.
posted by drezdn at 9:22 AM on December 6, 2007 [1 favorite]

In the world of fly-by-night weight loss suppliments, Cortisol is the main culprit in belly fat. It is a hormone which responds to stress levels and stores fat.

Their cure? Take magic pills and get six pack abs! At $45 a pop how could you not?
posted by munchingzombie at 9:26 AM on December 6, 2007

I'm not a biology student, but I think it is a mix of genetics and hormones. My mom and I both have pretty stubborn saddlebags, for instance. When I am on my rounder side, though my chest is bigger my body starts looking a lot more like hers.

Pregnancy hormones are the most obvious example of how they can change where someone deposits fat. During and after pregnancy most women find their bodies look very different than they did pre-pregnancy.

I think some people go on the extreme of the uneven scale just out of normal variations in the human population. If you think about "fat deposits" lying along the normal curve, where "normal" is even distribution about the body given age, gender, hormonal state, etc, then it might follow that some people on either tail of the curve will deposit it more unevenly in certain areas.
posted by schroedinger at 9:28 AM on December 6, 2007

You can't reduce fat on a particular spot. If that were so, chronic overeater's would have chubby bodies but slim, sexy jaws.
posted by munchingzombie at 9:29 AM on December 6, 2007 [2 favorites]

A significant part of it might be genetic, but I don't know of much modern research into it. There was an attempt to classify people into different body types, but that research isn't considered value by today's scientists.
posted by burnmp3s at 9:32 AM on December 6, 2007

Genetics.

(You'll read over and over again that there is no way to target fat loss in particular areas, but I sure do know a lot of cyclists who have rock hard, fat-free legs and an upper body of, um, a different consistency. Regardless, our differences in fat storage, taking exercise out of the equation, is just genetic. Same reason different people have different sized hips, boobs, etc.)
posted by iguanapolitico at 9:37 AM on December 6, 2007

I suppose it is a lot to do with genetics. Since you can't spot-reduce fat, you can't spot gain either. Diabetics and pre-diabetics tend to put most of their fat around the midsection. This is also where the term apple-shaped and pear-shaped comes from, apple=thicker midsection, pear=thicker bottom
posted by idiotfactory at 9:38 AM on December 6, 2007

Lipedema can cause a very disproportionate fat distribution concentrated in the hips, thighs, and calves, mainly in women. This is not a typical pear shape; it's much more dramatic.
posted by feathermeat at 9:50 AM on December 6, 2007

It's genetics, working through hormones such as leptin and cortisol. Treatments that affect hormonal balance will affect fat distribution, which is why some older women experience changes in body composition.
posted by Mr. Gunn at 9:51 AM on December 6, 2007

Cushing's Disease, which is caused by excess Cortisol, results in this uneven fat distribution. I am currently undergoing testing for this, in part because my recent rapid weight gain is all around the midsection, neck and face. I have perfectly normal arms and legs.
posted by Biblio at 10:21 AM on December 6, 2007

In addition to the above factors, I don't believe anyone has mentioned age. As age increases, fat storage becomes more concentrated in the midsection and less at the extremities (definitely true for men, pretty sure it's true for women also). This is will frequently see older men with very well defined arms and plenty of gut around the middle.
posted by christonabike at 11:12 AM on December 6, 2007

Well, gender, obviously, although you probably know that one. Otherwise it's genetics, mostly.

One thing causing confusion is that people will tend to sports which suit their body shapes. Someone with overly round thighs probably finds biking for long hours to be uncomfortable, so a study of bikers will show them to have more slender legs... but not because biking caused spot reduction.
posted by anaelith at 11:49 AM on December 6, 2007

Hormonal (which may be due to genetics but is usually because of lifestyle, diet and illness).
posted by gatchaman at 12:56 PM on December 6, 2007

i'm making this up as i go along, but to me it seems like a certain degree of human variance in fat storage is just one of those natural morphological variations in phenotype that a population has. something for natural selection to work on. i agree that it's bizarre- i mean, i know a woman with a tiny little ass and huge, ballooning, bulges of fat in her shoulders & upper back- and i don't ever notice weird phenotypical fat variances like that in squirrels or birds- but that's what i came up with.

oh, and i do know that some drugs can cause fat to relocate- for instance, some HIV medications can cause lipodystrophy, where the subcutaneous fat basically disappears, and instead fat deposits end up inside the abdomen and at the back of the neck- which makes the patient look gaunt in the face & limbs, with a "buffalo hump" and a swollen belly.
posted by pseudostrabismus at 1:21 PM on December 6, 2007