Do I have to give up animal foods completely?

What the experts say

Simon HillMSc, BSc · nutritionist and physiotherapist · host, The Proof

No. Plant-predominant is the prescription; plant-exclusive is his own preference.

What it rests onThe dietary-pattern trials he works from (CORDIOPREV, PREDIMED and the Dietary Portfolio) test patterns rather than exclusion, and his own meal plan offers salmon and Greek yogurt as named swaps. On red meat he separates quantity from presence: highest against lowest consumers shows a clear colorectal cancer increase, and in small amounts it likely will not affect risk.

Source: theproof.com ↗

Michael GregerMD · founder, NutritionFacts.org

For the marker that matters to him, partial does not move it.

What it rests onObservational comparison of vegans, vegetarians and omnivores on IGF-1 and binding capacity, read through his standing argument that growth signalling via IGF-1 and mTOR serves a child and costs an adult.

Source: nutritionfacts.org ↗

Overview

They are answering different questions with the same word. Greger's claim is about one biomarker in a comparison of dietary groups, and he is explicit that the target is IGF-1. Hill's claim is about a cardiovascular dietary pattern measured on lipids and plaque.

If you want the lowest possible IGF-1 and someone else wants the lowest possible ApoB, the two of you are not getting contradictory advice, you are getting advice aimed at different endpoints.

Where they agree

Substantial, which is what makes this worth showing. Both put legumes at the centre of the plate, both limit saturated fat, both treat ultra-processed food as a primary lever, both send readers to resistance training, and both publish a nutrient checklist for anyone eating plant-based (gre-b12-weekly and hil-vegan-nutrients, whose eight items are the longer list). Neither sells a supplement line.

What would settle it

For Hill: evidence that modest animal intake at the levels he describes carries a hard-outcome cost, rather than a biomarker cost, against an otherwise matched plant-predominant pattern. For Greger: hard outcomes tied to the IGF-1 difference, or a cohort in which the vegan-versus-vegetarian gap does not appear.

Practice does not pick a winner here

You do, and your call is dated, kept, and yours to change. Follow the people you already trust and what they publish turns into a short daily practice.

Record where you land on this, and change your mind later without losing the history
The 2 practices that follow from this question, graded and linked to the source
Everything else these people publish, read and graded, in one place

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