Background

The relationship between nutrition knowledge and health outcomes (e.g., obesity) is inconsistent. Similarly, undefined are the associations between nutrition knowledge and dietary choices (e.g., veganism). Differential outcomes may be related to discrepancies between perceived nutrition knowledge (PNK) and actual nutrition knowledge (ANK). This study explored how PNK and ANK were related to weight and dietary choices.

Methods

Participants(N=1,870) were adults recruited from Mechanical Turk to complete online surveys that included ANK (Consumer Nutrition Knowledge Scale), PNK (self-rated percentile), dietary choices (i.e., Vegan, Vegetarian) and motivations (i.e., Weight Loss, Health, Ethics), and self-reported height/weight.

Results

PNK was positively correlated with ANK(p<.001). BMI was negatively correlated with PNK(p<.001), but not with ANK. An ANOVA showed those with healthy weight reported higher PNK compared to individuals with obesity(p<.001) and those with underweight reported lower ANK compared to those with healthy weight, overweight, or obesity(p<.001). T-tests showed Vegans had greater PNK(p<.001), but not ANK, compared to non-vegans. Vegetarians had greater PNK(p<.001), but lower ANK(p<.001), compared to non-vegetarians. Those whose dietary choices were motivated by Weight Loss had similar PNK, but lower ANK(p=.022), compared to individuals not motivated by Weight Loss. Individuals motivated by Health had greater PNK(p<.001), but lower ANK(p=.009), compared to those not motivated by Health. Individuals motivated by Ethics had greater PNK(p<.001), but similar ANK, compared to those not motivated by Ethics.

Conclusions

BMI was significantly related to both ANK and PNK; individuals with underweight reported the lowest ANK and individuals with healthy weight reported greater PNK compared to individuals with obesity. Both PNK and ANK differed depending on dietary choices and motivations. The current findings may have implications for targeted obesity prevention and nutrition education.