The diets tested in the studies weren’t even the same as the official government advice — they were different and less strict.
Scientific Claim
The majority of randomized trials evaluating dietary fat reduction before 1983 did not implement the recommended targets of 30% total fat or 10% saturated fat, instead testing broader fat reduction or vegetable oil substitution.
Original Statement
“Five of the six RCTs did not examine either a total fat consumption of 30%, or a saturated fat consumption of 10%, of energy intake. The trials examined: the administration of vegetable oil; the replacement of saturated fats with vegetable oil; and an approximate 20% fat diet.”
Evidence Quality Assessment
Claim Status
appropriately stated
Study Design Support
Design supports claim
Appropriate Language Strength
definitive
Can make definitive causal claims
Assessment Explanation
This is a factual description of trial designs, directly supported by Table 1 and the methods section. The claim is precise and not overreaching.
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
Before 1983, scientists didn’t test the exact fat rules they later told people to follow — they tested looser changes like eating more vegetable oil, so the rules were made without solid proof.