In a recent study of more than 400 North American men and women whose previous heart attack put them at risk for a second heart attack, about half were told to switch to a "Mediterranean-type diet"—one rich in fish, vegetables, olive oil, and grains—while the other half were advised to eat a more traditional "Western" diet but to limit their fat intake.
Conclusion (so)
A diet can protect the heart even though it is not low in fat.
Evidence
Mediterranean diet has a good bit of fat, but meanwhile a study showed that people on a Mediterranean diet were less likely to have a second heart attack compared to those on a Western diet limiting fat.
Evaluate
This is the Explain Curious Fact template, because the author presents a non-causal comparison in the evidence and interprets a causal relationship from it.
CURIOUS FACT - why were the people following the Med Diet significantly less likely to have a second heart attack than those on a diff diet?
EXPLANATION - the Med Diet was protecting their heart
Goal
To strengthen the argument, we can either rule out alternate explanations for why people on the Med Diet were less likely to have a 2nd heart attack, or increase the plausibility of the causal relationship between the Med Diet and the lower heart attack risk.