The studies weren’t perfectly done — many didn’t hide who was on which diet, and people had to remember what they ate, which might have messed up the results.
Scientific Claim
The methodological quality of the six included randomized trials was moderate, with most lacking blinding and relying on self-reported dietary adherence, potentially introducing bias.
Original Statement
“Two were blinded for outcome assessment. Two were open, with no blinding on either side. ... The LA Veterans study was reported as double blinded, but the dietary changes were so substantial that this seems implausible. ... All trials relied on dietary advice, with meetings and periodical dietary analysis to monitor adherence.”
Evidence Quality Assessment
Claim Status
appropriately stated
Study Design Support
Design supports claim
Appropriate Language Strength
definitive
Can make definitive causal claims
Assessment Explanation
The claim accurately reflects the authors’ own assessment of study quality using the PEDro scale and narrative critique. No exaggeration is present.
Evidence from Studies
Supporting (1)
Evidence from randomised controlled trials did not support the introduction of dietary fat guidelines in 1977 and 1983: a systematic review and meta-analysis
The study found that the old diet rules were made without strong proof, because the experiments didn’t properly control for things like whether people actually followed the diet or if anyone was blinded to the results—so the results might be biased.