THE HFGVERDICT
Weightlosscanbeimpressiveona
VLCDespeciallyintheearlystages,
whichcanbemotivating.Butresearch
showsinthelongtermtheydon’ttend
togivebetterresultsthandietswith
moremoderatecalorierestrictions.Our
advice?A moremoderaterestriction
ispreferable,butif youthinka VLCD
mightworkforyouandsignificantly
improveyourhealth,askyourGPto
referyoutoa registereddietitianfor
advice.Remember,thesedietsshould
onlybeconsideredif youhavea
BMIof 30 ormore,havestruggled
withmoreconventionalweight-loss
strategiesandhavea medical
conditionthatwouldimmediately
improve with rapid weight loss.Thedownsides
Anycalorierestrictionwillusually
resultina lossofmuscleaswell
asfat.Oneconcernis thatvery
lowcalorieintakesresultina
dramaticlossofmuscle,whichin
turnslowsdownmetabolismso
evenfewercaloriesareneeded
tomaintainweight.However,in
onestudy,obeseadultsconsumed
810kcala dayforeightweeks,
thenswitchedto1,200kcalfor
anothereightweeks.Despite
losing12kgoverall(mostofit in
thefirsteightweeks),therewas
onlyan11%lossofmuscle at the
endofthe 16 weeks.
There’salsoevidence,though,
tosuggestlowercalorieintakesdo
resultina greaterlossofmuscle
thanmoremoderatediets.A
reviewofstudiesfoundthat,aftera
10kgweightloss,thosefollowing
a moderatecalorierestrictionhad
a 14%lossinmuscle,whilethose
wholostit witha VLCD showed a
23%lossinmuscle.
Therealityis thatmoreresearch
is neededtoconfirmtheimpact
VLCDshaveonouroverall
proportionoffatandmuscle.In
themeantime,wedoknowthat
exercise– bothaerobicand
strengtheningorresistance
activities– canhelpprotectagainst
musclelosswhendieting.Bearin
mind,somepeoplemaynothave
muchenergytoexercisewithan
intake of just 800kcal a day.
Thesideeffects
Therecanbeunpleasantside
effectssuchastiredness,
weakness,drymouth,headaches,
dizziness,insomniaandnausea.
However,theseareusually
short-livedandcanbehelped
bystayinghydrated.Verylow
calorieintakescanalsocause
constipation,diarrhoea,dryskin,
hairlossorthinning,cramps,
menstrualchangesandsensitivity
tocold.Rapidweight loss may
causegallstones.
Perhapsoneofthebiggest
problems with VLCDs is they’re
notmuchfun!Theyfailto
acknowledgethatfoodis an
enjoyableandnormalpartoflife,
sofamilylifemaypresenta
challenge,especiallyif youshop
andpreparemealsforothers.
Andsurvivingonshakesand
soupsdoesn’tsendouta positive
messageabouthealthyeating
tochildrenorteenagers.
Socialeventsthatinvolvefood
or drink may also be challenging.Willtheweight
stayoff?
Whiletheweightlossesseenwith
VLCDsareimpressive,thedrops
dotendtoslowdownasthe
weeksprogress.Andwhileall
theevidencesuggestsyou’lllose
weightmorequickly,studies
showthat,inthelongterm,
there’snotmuchdifferenceinthe
totalamountofweightlostwhen
comparedwithmoremoderate
restrictions.Thisis generally
becausethosewhofollowa VLCD
tendtoregainmoreweight.For
example,ina studyofaround
200 obesepatients,those
followinga VLCDlostweightmore
quicklythanthosefollowinga
dietthatrestrictedcaloriesbyjust
500kcala day,yetbothgroups
gainedaround70%ofwhatwas
lostjustunderthreeyearslater.
Partofthereasonforweight
regainmaybea compensatory
increaseinhungeraftera VLCD.
It’snotjustaboutlosingthe
hunger-supressingimpactof
ketones(seeWhatabouthunger?,
p35)oncecarbohydrateintake
increases.Afterfollowinga VLCD,
feelinghungrierandlesssatisfied
aftereatingis associatedwith
higherlevelsofthehunger
hormoneghrelinandlowerlevels
ofsatietyhormonessuchasleptin.
Fortunately,emergingevidence
suggeststhesehormonechanges
subsideif weightlossis maintained.
Thekeytokeepingtheweight
off,sayexperts,is toreintroduce
foodgraduallyandcontinue to
get professional support.JUNE 2019HEALTHY FOOD GUIDE 37