ROAR by Stacy Sims Review: The Science Behind the Book (2026)

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Is "eat and train like a small man" actually costing female athletes performance?

I haven't personally read ROAR cover to cover, so this isn't a reading diary — it's my professional assessment as a biotechnologist who works across both male and female clients, evaluating the book against Stacy Sims' own published research record. That distinction matters here more than with most products, because Sims isn't a wellness influencer repackaging other people's science — she's an exercise physiologist with an active publication record in this exact area, which changes how I'd weigh the book's claims.

What's actually in it

ROAR (Revised Edition, 2024) is built around a central argument: most exercise nutrition and training guidance was developed on male physiology and then scaled down for women, rather than built from female-specific data. The book covers menstrual cycle-based training and fueling, hormonal contraceptive effects, body composition, pregnancy, and a substantial menopause section — the last two being new full chapters in this revised edition. The 2024 update also adds material on wearables and recovery tracking (and where they fall short for female physiology), cold-water immersion, sleep science, and low energy availability (LEA) and relative energy deficiency in sport (RED-S), which have become much bigger concerns in the sports science world since the original 2016 edition.

What the research says

This is where ROAR stands apart from most books in this genre: its core author has published the underlying science herself. According to PubMed, Sims co-authored the International Society of Sports Nutrition's 2023 position stand on female athlete nutrition, which states directly that female athletes have hormone profiles that shift across the menstrual cycle and lifespan in ways that meaningfully affect carbohydrate needs, protein timing, and fluid and electrolyte balance — and recommends athletes track their hormonal status against training load to identify individual patterns (Sims et al., Journal of the International Society of Sports Nutrition, 2023). That same position stand specifically flags creatine and iron as having the strongest evidence base for female-specific supplementation, and recommends daily protein intake toward the upper end of standard ranges during the luteal phase and for peri/post-menopausal athletes.

Separately, an earlier methodology paper by Sims examined why so much exercise science historically excluded women or ignored menstrual cycle phase as a variable, and laid out the case for why hormonal status needs to be tracked and reported in research design going forward (Sims & Heather, Experimental Physiology, 2018). That paper is essentially the academic version of ROAR's central thesis — the book translates the same argument for a general readership.

How I'd evaluate this as a coach

What I'd flag as genuinely valuable: the menstrual cycle-based training and fueling framework isn't speculative — it's grounded in Sims' own peer-reviewed position stand, and the practical recommendations in the book (protein timing, carbohydrate periodization around cycle phase) track closely with what that 2023 paper actually says. The addition of full pregnancy and menopause chapters in this edition fills a real gap — most mainstream fitness content still treats both as afterthoughts. Where I'd want any reader to stay appropriately critical is the wearables and biohacking sections — Sims' own point there is that most trackers aren't calibrated for female physiology, which is a fair and useful caveat, but "detailed insight into biohacking" as a category still moves faster than the RCT evidence backing individual practices, so I'd treat those sections as reasonable starting frameworks rather than settled science.

Who this is actually worth it for

This is squarely for female athletes and active women across biotypes — the book's framework applies whether you're training for endurance, strength, or general fitness, since the underlying hormonal mechanisms it addresses (carbohydrate metabolism shifts, fluid balance, protein timing) aren't sport-specific. It's particularly relevant for anyone currently following a male-normed training or nutrition plan without adjustment, or anyone navigating perimenopause/menopause and finding that what used to work has stopped working. It's less essential for someone purely after workout programming with no nutrition or physiology component — this is a physiology-and-nutrition book first, training book second.

The honest verdict

ROAR earns its reputation because its central claim is backed by the author's own published research, not just packaged enthusiasm — that's a genuinely rare thing in this category of book. The revised edition's new chapters on menopause and LEA/RED-S track real, current concerns in sports science rather than padding for a re-release. The caveat is the same one I'd give for any single-author health book: treat the core hormonal-and-nutrition framework as strongly evidence-backed, and treat the newer biohacking-adjacent sections (wearables, cold plunge specifics) as reasonable but faster-moving territory where the science is still catching up. Worth reading for the framework alone.

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References:
1. Sims ST, Kerksick CM, Smith-Ryan AE, et al. International society of sports nutrition position stand: nutritional concerns of the female athlete. J Int Soc Sports Nutr. 2023. DOI
2. Sims ST, Heather AK. Myths and Methodologies: Reducing scientific design ambiguity in studies comparing sexes and/or menstrual cycle phases. Exp Physiol. 2018. DOI