The results of this study suggest that a daily intake of 120 mg NOPE and 105 mg of EGCG for 4-weeks, can enhance compliance to a low caloric diet, total mood score, feelings of fatigue, and confusion, but does not alter body mass or body fat to any greater magnitude than placebo. However, these benefits were not maintained by week 8 of the study, where only feelings of tension were reduced in comparison to placebo. These findings contrast with Rondanelli et al., in which sustained compliance and improvements in feelings of satiety, and severity of binge eating were observed for 8-weeks of study duration.
It is possible that the method used to determine dietary compliance may have contributed to the differences between the studies. In the present investigation, compliance was defined as the ability to maintain the recommended low caloric diet. Rondonelli and colleagues defined compliance in terms of drop-out rate. This may not entirely capture compliance, as approximately 72% of the participants, who did not drop out of the present study, were also unable to maintain the low caloric diet at one or more time points. This is supported by research investigating the psychological biases in self-reporting dietary habits in studies of caloric restraint[35, 36]. Although a participant may appear to be following the experimental protocol by not withdrawing, many may seek either to provide the results that researchers expect (compliance) or to make their actions appear socially desirable[35, 36]. Considering the lower daily caloric intakes of both groups, calculated from self-reported dietary recalls, greater reductions in body mass should have been observed. Regardless, differences in compliance through WK4 between the groups is likely attributable to the daily ingestion of NOPE. However, the 50 mg per day lower dose used in this study compared to previous research, may have resulted in some degree of habituation following 4-weeks of supplementation, as previous investigations have noted dose-dependency[19, 37].
It has been suggested that NOPE may curb appetite by slowing down gastric emptying and intestinal motility. While the present study did not measure gastric emptying and intestinal mobility directly, the lack of significant differences in caloric intake or feelings of satiety observed may reflect no differences in gastric emptying and intestinal mobility. Although both groups experienced reductions in caloric intake, possible differences may have been confounded by the participants’ physical activity habits. During lower intensity exercise (< 70% VO2max), caloric intake may increase due to stimulated gastric emptying[40, 41], while more strenuous exercise may delay gastric emptying, thus decreasing appetite. Considering that exercise patterns were similar between the groups, it is possible that the potential influence of NOPE on appetite[38, 39] likely enhanced dietary compliance through WK4.
The NOPE and EGCG combination has also been reported to reduce the severity of binge eating to a significantly greater degree than placebo. While the present investigation noted decreases in BES scores for both groups, no significant differences were observed at any time point. However, baseline measurement scores suggest that neither group could be defined as binge eaters, which may imply that this proprietary supplement blend may be more effective in binge eaters. It is likely that reductions in BES scores in both groups may have also been the result of the combined diet and exercise program, as several studies have shown that a combination of diet and exercise may prevent the onset of binge eating in non-binge eaters[42, 43].
The present investigation does support previous findings that the NOPE-EGCG blend can significantly enhance mood. Oral supplementation of EGCG has been suggested to impact central nervous system function in the brain[44–46] by affecting γ-aminobutyric acid receptor binding sites (GABAA). Since γ-Aminobutyric acid is the principal inhibitory neurotransmitter receptor system in the brain that regulates anxiety, EGCG ingestion may reduce anxiety. EGCG was been shown to reduce anxiety in mice[48, 49], while regular green tea consumption lowers post-stress cortisol levels and increases subjective relaxation in humans. Our findings show that mood, feelings of depression and confusion are all improved after four weeks of supplementation, with improvements in feelings of tension thereafter.