#NEWS

EX­ER­CISE YOUR MUS­CLE MOL­E­CULE

Guru Magazine - - Contents - Au­thor: Si­mon Makin

Su­per-brain Ross Harper writes about some­thing to do with wa­ter-clean­ing carbon nan­otubes and Si­mon Makin cov­ers a story about the weird things that hap­pen when you ex­er­cise. It’s the news you al­most cer­tainly missed. Page 22 is where you want to be.

Was one of your New Year’s res­o­lu­tions to get more ex­er­cise? How’s that “work­ing out” for you? Would it help if you knew ex­actly how ex­er­cise has such long-last­ing ef­fects on good health? Well Guru is here to tell you that sci­en­tists have just made a big step for­ward in un­der­stand­ing ex­actly that. Think of it as a geeky pep talk… A land­mark new study has found that ex­er­cise not only makes your heart and mus­cles stronger but may ac­tu­ally change the type of fat in your body. Re­searchers dis­cov­ered that ex­er­cise trig­gers mus­cles to pro­duce a small mol­e­cule that trav­els through the blood and into ‘white’ fat, chang­ing it into calo­rie-burn­ing ‘ brown’ fat. This trans­for­ma­tion may be a ‘miss­ing link’ be­tween ex­er­cise and its wide-rang­ing ben­e­fits. There are two kinds of fat. Every­body knows about hor­rid white fat – the stuff that gives us adorable ‘love han­dles’ and ‘bingo wings’ – but its lesser known cousin, brown fat, is a very dif­fer­ent beast. White fat cells are where our bod­ies store en­ergy from the food we eat. Think of them as fuel stores; we need that re­serve just in case we don’t eat enough to fuel our daily ac­tiv­i­ties. But snaf­fle more calo­ries than you use up each day and you’ll start to get big­ger. Brown fat cells are more like fuel burn­ers – they burn fat to gen­er­ate heat. Sci­en­tists used to think brown fat was only found in new-born ba­bies and dis­ap­peared by adult­hood, but we now know that most adults still have some. Also – in­ter­est­ingly – it tends to be more plen­ti­ful in thin peo­ple.

So what does this have to do with ex­er­cise? Well, re­searchers from Bruce Spiegelman’s lab at Har­vard Med­i­cal School in Bos­ton, MA, found that when mus­cles are ex­er­cised they re­lease a newly-dis­cov­ered hor­mone called irisin – and irisin can make white fat be­have more like brown fat. Th­ese ex­per­i­ments were done on mice, al­though lots of re­searchers are pretty con­fi­dent that the same thing hap­pens in hu­man mus­cle It’s not yet clear whether irisin af­fects all hu­mans in the same way though, as other re­searchers could only find ef­fects in el­derly peo­ple.

Fit­ness in a bot­tle

Irisin isn’t the whole pic­ture how­ever. In this lat­est study a team led by Robert Ger­szten, in col­lab­o­ra­tion with Spiegelman’s group, found another sub­stance called beta-aminoisobu­tyric acid (or BAIBA for short). BAIBA is much smaller than irisin (a sin­gle amino acid for the real geeks out there), but has been found to ‘brown’ the white fat cells by mak­ing their DNA be­have more likea brown fat cell. BAIBA also en­cour­ages liver cells to break down fats – a sure sign of in­creased me­tab­o­lism. In­deed, mice given wa­ter laced with BAIBA to drink had a higher me­tab­o­lism, healthier blood su­gar, and lost weight. To check whether th­ese ef­fects are likely to ap­ply to hu­mans, the sci­en­tists an­a­lysed sam­ples from over 2000 pa­tients (from the long-run­ning Fram­ing­ham Heart Study) and found that peo­ple with low lev­els of BAIBA in their blood had high choles­terol lev­els – putting them at a higher risk of heart disease – and more in­sulin re­sis­tance – putting them at risk of di­a­betes. But when peo­ple had taken part in a 20 week ex­er­cise pro­gramme, as part of another study, their BAIBA blood lev­els in­creased by 17%. The re­searchers now think that hav­ing more BAIBA pro­tects you from con­di­tions like di­a­betes and heart disease. It could there­fore be used as the in­spi­ra­tion for new treat­ments – per­haps even in the de­vel­op­ment of drugs to fight obe­sity, or even just to help peo­ple lose weight. Maybe your doc­tor could even test your BAIBA lev­els and find out how much ex­er­cise you have re­ally been do­ing! But we shouldn’t get too ex­cited just yet: there’s still a lot of work to be done, such as find­ing out if BAIBA has any un­fore­seen side ef­fects in an­i­mals, be­fore they can even start down the road to­wards drug de­vel­op­ment. So don’t go turn­ing in your gym shoes just yet – there’s still no sub­sti­tute for a good old-fash­ioned work out.

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