Likely one of the best-scoring named diets on this entire list — with one debatable rule.
Engine 2 is a strict whole-food, plant-based approach — no meat, dairy, or added oils, even olive oil — popularised by former firefighter Rip Esselstyn after his fire station colleagues saw dramatic cholesterol improvements following the plan.
| Dimension | Engine 2 Diet | THE FAD |
|---|---|---|
| Core rule | Strict whole-food, plant-based diet with no added oils, no animal products, and minimal processed food | No food group excluded, no oil restriction |
| Origin | Developed by Rip Esselstyn, a former firefighter, based on his fire station's health results | N/A |
| Overlap | Extremely high fibre, extremely low added sugar and processed food — likely one of the highest-scoring named diets on THE FAD | Would reward this pattern very strongly across multiple Food signals |
An Engine 2-style pattern — heavy on vegetables, legumes, whole grains and fruit, essentially free of ultra-processed food and added sugar — would likely score very well across nearly every Food signal THE FAD tracks.
The no-added-oil rule (including olive oil) goes further than the research on healthy fats generally supports — most nutrition research favours olive oil over eliminating fat sources entirely. This is one place where Engine 2's rules are stricter than what THE FAD's evidence-based Food signal would actually require.
The best way to understand the difference is to see what a real day scores.
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