The condition that means you can’t get fat

It sounds like something you’d WANT to have — but it can be life-threatening . . .

Rebecca SanderS often gets compliments on her toned upper arms from women desperate to get rid of their bingo wings. at 34, rebecca has only 11 per cent body fat, on a par with an elite athlete, as well as a six pack and muscular legs. by comparison, the average woman has around 32 per cent body fat.

For years, rebecca had an enormous appetite but never looked overweight.

but this is not the result of time spent at the gym. In fact, rebecca has a serious metabolic condition that could shorten her life. ‘The irony is that although I look muscular and fit, I’m actually very sick,’ says rebecca, a scientist from Teddington, South-West London.

She has familial partial lipodystrophy (FPLd), an inherited condition that causes abnormal distribution of fat cells.

‘I can’t store fat cells apart from in my face and muscles and around my organs,’ she explains. ‘People might think I’m lucky that I can’t get fat, but most of my fat is stored around my organs, which can damage them.

‘Other fat is stored in muscle cells — which gives me a muscular appearance — and in my blood, which means I have high cholesterol and triglyceride levels which make me more prone to heart disease.’

FPLd is one of several conditions known as lipodystrophies, characterised by complete or partial loss of fat tissue. although rare — only around 100 people in the UK are diagnosed with inherited lipodystrophy — some experts say numbers may be much higher as signs such as a muscular physique or big appetite can be missed, especially in men.

Scientists believe it could hold a key to finding out about more common conditions such as type 2 diabetes — and why some slim people develop it.

Some cases of lipodystrophy are caused by a fault in genes responsible for making proteins that play an important role in fat storage. Parents who have the faulty gene have a 50 per cent chance of passing it on to their children. rebecca and her twin inherited it from their father.

Those affected look normal at birth but from around puberty, their fat distribution changes.

as fat is stored in muscles this can trigger metabolic disorders such as insulin resistance, a precursor to diabetes; and women can also develop polycystic ovary syndrome (PcOS), which causes hirsutism, explains rebecca.

another distinctive symptom of FPLd is an enormous appetite. That’s because fat cells all over the body normally produce a hormone called leptin that tells the brain when the stomach is full. because patients have fewer fat cells, they have very low levels of leptin and so the brain doesn’t get the message about being full.

as a child, rebecca always felt hungry. ‘Then, as an adult, I could go out for a three-course meal and eat burger and chips on the way home or demolish a few packets of biscuits,’ she says. but she didn’t look fat. ‘My sister and I just thought we had fast metabolisms.’

Professor Stephen O’rahilly, director of the University of cambridge metabolic research laboratories, says FPLd is rare — ‘I’d estimate less than 50 per cent of females with it have been diagnosed and less than 10 per cent of men’ — but adds he’s recently seen a patient who was diagnosed after nearly 40 years of symptoms.

Lipodystrophy can be identified by genetic tests and blood tests for insulin levels, cholesterol and triglycerides.

rebecca was diagnosed at 17 when she developed irregular periods and was tested for PcOS; her insulin levels were 50 times higher than normal. Luckily, her endocrinologist had heard of lipodystrophy and sent her for tests.

‘I felt fortunate to be diagnosed quickly after puberty,’ says rebecca. ‘Many can be misdiagnosed as having uncontrolled diabetes or told off for eating badly.’

as a result of her condition, rebeccca already has a severe form of type 2 diabetes and needs insulin daily. ‘I also have PcOS so my fertility may be affected, and I have high cholesterol so I need to take statins, as well as medication for high blood pressure.’

When rebecca was diagnosed, there was no treatment for FPLd. but while studying biochemistry at university, rebecca heard of an experimental treatment — injections of artificial leptin.

‘It was originally developed to tackle obesity. I contacted the University of cambridge to ask if I could join a trial.’

Shebecame one of the first patients in the UK to be given leptin injections. Within three months she needed less insulin, had a reduced appetite and the amount of fat in her liver dropped dramatically.

but now rebecca fears that soon the leptin jabs may no longer be available, as leptin hasn’t been found to be successful in treating obesity, and the company that makes the injections, aegerion, may have to stop funding it.

Leptin jabs for lipodystrophy are about to undergo nIce appraisal, with guidance on its use in the nhS to be published in September. ‘I’m fearful of what will happen if I can’t get the leptin,’ says rebecca, ‘I just cannot go back to feeling hungry all the time.’