More fat less fat

The Penn sci­en­tist is look­ing to har­ness brown fat’s power to burn ex­tra calo­ries.

Gulf Times Community - - FRONT PAGE - By Sandy Bauers

I still strug­gle all the time with los­ing weight. Maybe that’s why I’m fas­ci­nated with it. I just find it in­ter­est­ing to think about how all this works. — Pa­trick Seale, re­searcher

But be­fore you reach for the potato chips, know that they’re talk­ing about a dif­fer­ent kind of fat – brown fat, which is rad­i­cally apart from the white fat that char­ac­terises obe­sity. In a sense, they’re op­po­sites. One burns en­ergy; the other stores it.

Pa­trick Seale, as­so­ciate pro­fes­sor of cell and de­vel­op­ment bi­ol­ogy at the Uni­ver­sity of Penn­syl­va­nia’s Perel­man School of Medicine, stud­ies fats and their re­la­tion­ship to metabolic dis­eases such as di­a­betes.

Re­cently, the En­docrine So­ci­ety, an in­ter­na­tional as­so­ci­a­tion fo­cus­ing on hor­mone re­search, an­nounced that he was one of 13 lead­ing en­docri­nol­o­gists to get one of its an­nual Lau­re­ate Awards. Seale re­ceived the Richard E. Weitz­man Out­stand­ing Early Ca­reer In­ves­ti­ga­tor Award for his study of brown fat.

Seale knows these is­sues both as a sci­en­tist and as a reg­u­lar guy. “I still strug­gle all the time with los­ing weight,” he said dur­ing a re­cent in­ter­view about his work. “Maybe that’s why I’m fas­ci­nated with it. I just find it in­ter­est­ing to think about how all this works.”

How dif­fer­ent are brown and white fat? Are they re­ally those colours?

They’re very dif­fer­ent. Brown fat func­tions to burn en­ergy, and it does this to make heat. The heat is re­ally im­por­tant, es­pe­cially in small an­i­mals, for main­tain­ing body tem­per­a­ture. For ex­am­ple, mice that have de­fec­tive brown fat can’t sur­vive in the cold.

White fat is the most preva­lent fat tis­sue, es­pe­cially in hu­mans. Its main func­tion is to store en­ergy. It ex­pands when peo­ple eat more than they burn off.

They ac­tu­ally are dif­fer­ent colours. Brown fat looks brown, and the rea­son is it has a lot of mi­to­chon­dria – what can be con­sid­ered the en­ergy pow­er­houses of the cell. They es­sen­tially make en­ergy for cells, and brown fat has a lot of them.

The colour of white fat is de­ter­mined by the lipids that are stored there. It’s not re­ally that white. In hu­mans, it’s more of a yel­low tinge. In mice, it’s white.

White fat is found in the sub­cu­ta­neous re­gion – right un­der your skin and it sur­rounds your in­ter­nal or­gans. It forms in a lot of places. It’s far and away the largest type of fat that hu­mans have.

Brown fat – there’s a lot less of it. And it’s in very spe­cific places. The place it’s found in the largest quan­ti­ties is right around the col­lar bone. There are also small amounts along the spinal col­umn, and quite a bit in the neck. We don’t re­ally know why.

It might be that the col­lar bone, spinal col­umn, and neck are just a good place to be for warm­ing the blood ves­sels. Brown fat prob­a­bly did not form to keep us from be­com­ing obese. It prob­a­bly evolved to keep us warm. The heat that it makes can quickly get to the rest of the body.

So is brown fat re­ally good for us, while white fat is not?

That’s ac­tu­ally a lit­tle more com­pli­cated. They’re both good.

Brown fat is good for us be­cause it can burn ex­tra calo­ries; it can ex­pend calo­ries that you don’t want to store. You can kind of think of it a lit­tle like ex­er­cise. It will burn en­ergy, ex­cept you don’t have to work. This en­ergy would oth­er­wise be stored in the body, so it ac­tu­ally coun­ter­acts obe­sity in that way. It’s very clear that mice with more brown fat do very well. They are pro­tected against obe­sity and di­a­betes.

White fat is also good. The rea­son is that it’s es­sen­tially a safe place to store lipids. Obe­sity hap­pens when more en­ergy is taken in than is ex­pended. That en­ergy has to go some­where. Up un­til a cer­tain point, white fat can han­dle it. The en­ergy is con­verted to lipid and stored in white fat. How­ever, if the over­sup­ply of en­ergy is chronic, the fat cells even­tu­ally be­come over­bur­dened and aren’t able to store the lipid any­more. It ends up go­ing to liver, pan­creas or mus­cles, and that causes all kinds of prob­lems.

Can we get more brown fat by al­ter­ing what we eat?

Not that we know of. There’s a lot of in­ter­est in that. Large phar­ma­ceu­ti­cal com­pa­nies are try­ing to fig­ure out how we can make more brown fat.

The one thing peo­ple can do is to ex­pose your­self to the cold. There are a lot of peo­ple who think that is a good thing to do.

How cold? It’s dif­fer­ent for each per­son. Cer­tainly not to the point where you shiver. There are a lot of stud­ies now look­ing at re­duc­ing en­vi­ron­men­tal tem­per­a­ture to see if that can have ef­fects on obe­sity and di­a­betes. It’s very promis­ing.

In one Ja­panese study, sub­jects sat in a cold room – 66 de­grees Fahren­heit – for two hours a day over the course of six weeks. Peo­ple lost quite a bit of weight.

There’s a lot of in­ter­est in find­ing other ways to in­crease the func­tion of brown fat.

Tell us more about your re­search.

A lot of what we are try­ing to do is to fig­ure out the ge­netic path­ways for how both brown and white fat cells are made. We’re try­ing to un­der­stand the mol­e­cules and all the fac­tors that go into this, with the thought that we’ll fig­ure out how to make more of it or stim­u­late it in dif­fer­ent ways for ther­a­peu­tic ef­fect.

The other thing we fo­cus on is de­vel­op­ing an­i­mal mod­els so that we can un­der­stand what goes wrong in the set­ting of obe­sity and di­a­betes – how that af­fects fat tis­sue, both brown and white – and how we might be able to change the prop­er­ties of that tis­sue to af­fect di­a­betes. When an an­i­mal or hu­man gets obese, that has ma­jor ef­fects on the fat tis­sues. So we’re try­ing to un­der­stand what is hap­pen­ing – what is good, what is po­ten­tially bad – so we can think about ways to in­ter­vene. If we un­der­stand the bad con­se­quences, we might be able to block the ef­fects. If we un­der­stand the good con­se­quences, we might be able to pro­mote them.

We now know a lot about how these dif­fer­ent types of fat tis­sues work, and about the ge­netic fac­tors that con­trol them. What’s needed now is to try to find ways to ma­nip­u­late it, to try to find ther­a­pies that tar­get the fat tis­sue, for fight­ing obe­sity as well as di­a­betes. In par­tic­u­lar, brown fat holds a lot of prom­ise for fight­ing obe­sity. It’s a tough thing to crack, but that’s prob­a­bly where the main thrust of the field is – how we can use our knowl­edge and de­velop ways to tar­get brown fat to fight obe­sity. We have pretty good drugs for di­a­betes. Obe­sity is trick­ier. And obe­sity is often the thing that ini­ti­ates these other prob­lems.

Peo­ple tend to think fat is just bulky, but so much sci­ence is re­veal­ing that it’s ac­tu­ally more like an or­gan that does all kinds of in­ter­est­ing things.

Ab­so­lutely. Even in the sci­ence com­mu­nity, it was pre­vi­ously thought of as an in­ert or­gan that is a by­stander. Now, we know so much more about it. There are many dif­fer­ent types of fat tis­sue. We’ve talked about brown and white. In ev­ery place in the body, the fat tis­sue is prob­a­bly slightly dif­fer­ent and do­ing dif­fer­ent things, prob­a­bly hav­ing im­por­tant func­tions.

The other thing we know now is that, rather than be­ing an in­ert or­gan, it makes a lot of hor­mones that com­mu­ni­cate with other or­gans in the body. It makes things to talk to the brain, that talk to the mus­cles. I would say it co-or­di­nates or con­trols a lot of me­tab­o­lism. It’s re­ally an im­por­tant thing to study. –

RE­SEARCHER: Pa­trick Seale, as­so­ciate pro­fes­sor at the Uni­ver­sity of Penn­syl­va­nia’s Perel­man School of Medicine, has been study­ing fats.

WEIGHT LOSS: An un­named woman in a gym. The weight many of us are try­ing to lose is white fat, tis­sue that stores en­ergy. Sci­en­tists think more en­er­gy­burn­ing brown fat – which ex­ists in small de­posits along the spine and neck – might help that ef­fort.

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