A restrictive opening phase, and a much more balanced finish.
The Dukan diet, developed by French physician Pierre Dukan, is a phased high-protein plan — the strictest early phase permits only lean protein, before vegetables and other foods are gradually reintroduced over the following phases.
| Dimension | Dukan Diet | THE FAD |
|---|---|---|
| Core rule | A four-phase, high-protein plan starting with a strict pure-protein phase, gradually reintroducing vegetables and other foods | No phases — ongoing scoring of whatever you eat, any day |
| Origin | Developed by French physician Pierre Dukan, highly popular in Europe in the 2000s-2010s | N/A |
| Common critique | The strict early phases are very low in fibre and plant diversity — a gap most nutrition experts flag | Rewards fibre and plant diversity directly, regardless of protein intake |
The initial pure-protein phase is very low in fibre and plant diversity — two of THE FAD's more heavily weighted Food signals — which is also one of the more common nutritional critiques of the diet from dietitians generally.
As vegetables and other whole foods are reintroduced in later phases, a Dukan-style pattern would likely score considerably better — the diet's later, more balanced phases have much more in common with THE FAD's Food signal than its restrictive opening phase.
The best way to understand the difference is to see what a real day scores.
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