Thesis (MNutr)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: It is estimated that 1.3 billion people worldwide are either overweight or obese, making this a global epidemic. An effective weight-loss method involves the lifestyle changes of increased physical activity and lowered energy intake. These changes are difficult to carry out and to maintain. As a result, there is a soaring demand for weight-loss aids, including dietary supplements, which exploit consumers’ eagerness to find an effortless weight-loss solution. These supplements are easily accessible, require no prescription and are heavily marketed to suggest that weight loss is achievable without exercise and dieting. One such dietary supplement, Bioslim, is tested in this study. The aim of this study was to investigate whether Bioslim results in greater weight loss than a placebo, and whether the marketing of the Bioslim brand has an influence on the placebo response. Overweight adults residing in Cape Town (n = 87) were recruited by advertising in community newspapers and setting up stands at shopping centres. The subjects were randomised into one of four groups: Bioslim in Bioslim packaging (n = 26), Bioslim in unbranded packaging (n = 22), placebo in Bioslim packaging (n = 17) and placebo in unbranded packaging (n = 22). At baseline, the subjects were given one of the four products and anthropometric measurements (weight, height and skinfold thickness) were taken. After four weeks, these measurements were repeated. The subjects also had to complete a questionnaire regarding their experiences. The body mass index (BMI) for the total population was 31.90 kg/m2 (SD = 3.91) at baseline and 31.89 kg/m2 (SD = 3.92) at follow-up. None of the measured anthropometric variables had changed significantly after four weeks. When the total study group sample was analysed, based on the allocated drug treatment groups (active or placebo), neither group showed significant weight loss from baseline to follow-up. Twenty-three subjects from the Bioslim group and 21 from the unbranded group reported exercising during the trial. The total group’s exercise time correlated significantly with fat-mass reduction (r = -0.31, p = 0.004). Furthermore, when data was analysed separately for the active and placebo groups, the active group showed a significant correlation (r = -0.45, p = 0.0012), while the placebo group showed an insignificant correlation (r = -0.05, p = 0.77). The same was not reflected in weight loss (r = -0.007, p = 0.95). It is concluded that Bioslim is an ineffective weight-loss supplement: subjects receiving active pills evidenced no significant beneficial changes in weight, waist circumference or body composition. More than half of the subjects attempted dieting and exercising, but these efforts were insufficient to impact on weight loss. The marketing and packaging of Bioslim did not enhance the placebo effect. One subject from the active group withdrew from the study, complaining of severe headaches and heart palpitations. There was no difference in adverse events reported by the remaining active and placebo group subjects. In conclusion, this study emphasises the need for better regulation of the efficacy and safety of dietary supplements. / AFRIKAANSE OPSOMMING: Daar word geskat dat 1.3 biljoen mense wêreldwyd oorgewig of vetsugtig is, wat dit ‘n globale problem maak. ‘n Effektiewe gewigsverlies metode inkorporeer leefstyl veranderinge soos verhoogde fisiese aktiwiteit en ‘n laer energie inname. Hierdie veranderinge is moeilik om uit te voer en vol te hou. Die gevolg is ‘n stygende aanvraag vir gewigsverliesprodukte en supplemente, wat verbruikers se gretigheid om ‘n maklike gewigsverlies oplossing te kry, uitbuit. Hierdie supplemente is maklik verkrygbaar sonder ‘n voorskrif en word aggressief bemark met bewering dat gewigsverlies moontlik is sonder oefening en dieetaanpassing. Een van die beskikbare produkte, Bioslim, is getoets in die studie. Die doel van die studie was om te ondersoek of die gewigsverlies produk, Bioslim, lei tot ‘n groter gewigsverlies as ‘n plasebo produk en of die bemarking van die Bioslim handelsmerk ‘n invloed op die plasebo-effek het. Oorgewig volwassenes woonagtig in Kaapstad (n = 87) is gewerf deur advertering in gemeenskapskoerante en deur stalletjies by inkopiesentrums. Die proefpersone is ewekansig in vier groepe ingedeel: Bioslim in Bioslim verpakking (n = 26); Bioslim in verpakking sonder ‘n handelsmerk (n = 22); ‘n plasebo produk in Bioslim verpakking (n = 17) en ‘n plasebo produk in verpakking sonder ‘n handelsmerk (n = 17). Met aanvang van die studie is een van die vier produkte aan die proefpersone gegee en antropometriese metings (gewig, lengte en velvoudikte) is gemeet. Metings is na vier weke herhaal. Die proefpersone moes ook ‘n vraelys oor hul ervarings voltooi. Die liggaamsmassa indeks (LMI) van die totale populasie was 31,90 kg/m2 (SD = 3.91) by basislyn en 31.89 kg/m2 (SD = 3.92) met opvolg. Geen van die antropometriese veranderlikes het betekenisvol verander na vier weke nie. Met ontleding van die totale studie polulasie, gebasseer op die toegekende behandeling (aktiewe of plasebo bestanddele), is gevind dat geen groep ‘n betekenisvolle gewigsverlies getoon het van basislyn tot opvolg nie. Drie-en-twintig proefpersone uit die Bioslim groep en 21 uit die geen-handelsmerk-groep het gerapporteer dat hul geoefen het gedurende die studie. Die totale groep se oefenings tydsduur het betekenisvol gekorreleer met ‘n verlaging in vetmassa (r = -0.31, p = 0.004). Met verdere analiese van die data in die aktiewe en plasebo groepe, is gevind dat die aktiewe groep ‘n betekenisvolle korrelasie getoon het (r = -0.45, p = 0.0012), maar die plasebo groep nie (r = -0.05, p = 0.77). Hierdie bevinding is nie gevind in die gewigsverlies nie (r = -0.007, p = 0.95). Die gevolgtrekking word gemaak dat Bioslim ‘n oneffektiewe gewigsverlies supplement is, aangesien proefpersone wat die aktiewe pille geneem het, geen betekenisvolle voordelige veranderinge in hul gewig, middelomtrek of liggaamsamestelling getoon het nie. Alhoewel ‘n betekenisvolle korrelasie gevind is tussen oefeningsduur en verlies aan vetmassa in meer as die helfte van die proefpersone, was die omvang daarvan onvoldoende om ‘n impak op hul gewigsverlies te hê. Die bemarking en Bioslim handelsmerk het nie die placebo-effek versterk nie. Een persoon uit die aktiewe groep het van die studie onttrek as gevolg van erge hoofpyn en hartkloppings. Daar was geen verskil in die nadelige effekte gerapporteer deur die oorblywende proefpersone in die aktiewe en plasebo groepe nie. Ten slotte beklemtoon die studie die behoefte aan beter regulering van die effektiwiteit en veiligheid van dieetsupplemente.