How we test & source

Who built this

Carb Hack is built by Croix, a software engineer with a biomedical-engineering background and endurance athlete based in Boulder, Colorado.

Biomedical engineering is the relevant background for the kind of analysis on this site — transporter kinetics, osmolality calculations, cost modeling, ingredient selection. It is not a clinical credential. Nothing on Carb Hack is written by a registered dietitian, sports physician, or certified nutritionist. If a page ever carries a clinical reviewer byline, it will name a real, verifiable RD or CSSD with their credentials and license state visible. Until then, treat everything as engineering analysis of public information.

How recipes are formulated

Every DIY recipe starts from the commercial product's own published label: total carbs per serving, glucose-to-fructose ratio, sodium dose, calorie count, and stated serving volume. Those numbers are the target.

From there, the steps are mechanical:

1. Pick bulk ingredients that, in proportion, recreate the same glucose and fructose grams — most often maltodextrin (glucose polymer, low osmolality) plus pure fructose. For Skratch Super High Carb, HBCD (cluster dextrin) replaces maltodextrin to keep osmolality lower at high carb concentrations. For Tailwind Endurance Fuel, table sugar plus a pinch of dextrose hits the same glucose-fructose split from grocery-store ingredients.
2. Add table salt or food-grade sodium citrate to hit the same sodium dose. Sodium content is normalized by mg of Na per serving, not by mg of NaCl.
3. Dissolve in the same volume of water the commercial product specifies, so concentration and osmolality are matched.
4. Cost is calculated from whichever of Nutricost direct, iHerb, or Amazon offers the better unit price for each ingredient at the time of the page's last review. HBCD is the one exception: neither Nutricost nor NOW Foods stocks pure HBCD, so HBCD-based recipes price against a specialty-supplement-vendor estimate. Per-serving cost reflects only ingredients — we don't bill for packaging, shaker bottles, or your time.

The math behind all of this lives in the Builder — the same engine that runs each DIY page is exposed for you to tune sodium, carbs, ratio, and concentration to your own physiology.

Where the science comes from

The bulk of the credibility chain on Carb Hack runs through FDA nutrition labels, not the journal literature. Every DIY recipe replicates the published spec of a real, on-shelf commercial product — carbs, ratio, sodium, powder weight — and the Methodology page shows the spec-by-spec match for each one.

Where a claim isn't derivable from a label — transporter saturation, the 1:0.8 glucose-to-fructose argument, the modern 120 g/hr ceiling, or the hydrogel skepticism that contradicts Maurten's marketing — we cite the peer-reviewed source in line. The three papers that do the load-bearing work:

1. Jeukendrup, A. (2014). A step towards personalized sports nutrition: carbohydrate intake during exercise. Sports Medicine. Google Scholar →The dose-rate framework — 30, 60, 90 g/hr by exercise duration — that the entire sports-nutrition industry now uses.
2. O'Brien, W.J., Stannard, S.R., Clarke, J. & Rowlands, D.S. (2013). Fructose-Maltodextrin Ratio Governs Exogenous and Other CHO Oxidation and Performance. Medicine & Science in Sports & Exercise. Google Scholar →Twelve-cyclist sprint-performance study (10 × 2-min maximal sprints after 2 hours of steady-state riding at 57% peak power) that established 1:0.8 glucose-to-fructose as superior to 2:1 on oxidation efficiency, power output, and GI tolerability.
3. Podlogar, T. & Wallis, G.A. (2022). New horizons in carbohydrate research and application for endurance athletes. Sports Medicine. Google Scholar →The current consolidated review of high-carb fueling — pushes the modern ceiling to ~120 g/hr, and reviews the matched-dose hydrogel literature that has not reproduced a benefit over standard 1:0.8 drinks.

Plain-English summaries of the formulation principles — with these references attached — live on the Science page.

What gets verified in-house

The math gets checked. Every published recipe is run through the same mix-analysis engine that powers the Builder, and the engine itself is covered by a unit test suite that asserts known cases against the literature. If the analyzer ever disagrees with the label of a commercial product we're reverse-engineering, the disagreement is reconciled before the page ships.

Dissolution and taste get checked at the kitchen scale. The recipes use ingredient quantities that dissolve cleanly in room-temperature water. Where a formulation sits at a problematic osmolality (above ~12% concentration is GI-risky for most riders), the page calls that out instead of pretending it doesn't.

Cost gets checked at every page review. Bulk-ingredient listings shift — pack size, shipping, promotions — and the per-serving cost on each DIY page reflects the cheapest of Nutricost direct, iHerb, or Amazon at the page's last reviewed date. A "Last reviewed" line at the top of every DIY page tells you when the cost numbers were last spot-checked.

What does not get verified in-house

We don't run our own randomized controlled trials. We don't do exogenous-carb-oxidation tests, gastric-emptying scans, or blinded performance-tolerability comparisons. Those exist in the literature cited above, and the literature is what the physiological claims rest on. If you see a performance, oxidation, or GI claim on Carb Hack, it should be traceable to a named paper or its absence should be flagged.

We don't certify ingredient purity. The bulk ingredients we link to are food-grade products from Nutricost (direct, via iHerb, or via Amazon) and NOW Foods (the fructose fallback, via iHerb or Amazon) — all manufactured in GMP-compliant, FDA-registered facilities and third-party tested at the brand level — but we don't run our own mass-spectrometry on them. If you compete under WADA / NSF Certified for Sport requirements, source from a sport-certified batch — commodity bulk maltodextrin (every brand we link, included) is generally not third-party-tested for sport.

We don't give individualized advice. Sodium needs vary five- to ten-fold rider to rider; carb tolerance varies almost as much. The recipes are starting points calibrated to a typical 65–75 kg endurance athlete. Tune them to yourself and, when in doubt, talk to a sports dietitian.

How I make money — and what that does not mean

Carb Hack is funded by affiliate commissions. When you buy a bulk ingredient through one of the "Buy" buttons on a DIY page, the site earns a small commission at no extra cost to you. Ingredient links go to whichever of Nutricost direct (nutricost.com), iHerb (iherb.com), or Amazon offers the best unit price for a given product — the site participates in each vendor's affiliate program, including the Amazon Associates program. Competitor product comparisons on the /compare pages also link to Amazon where applicable.

Two things that do not follow from that:

• I don't pick a recipe or rate a product based on commission rate. Each ingredient links to whichever of Nutricost direct, iHerb, or Amazon has the better unit price at review time — even though Amazon's grocery commission rate is roughly 6× lower than the direct vendor programs. If a cheaper or more appropriate source exists for a given ingredient (sucrose at the grocery store, for example), the page says so and skips the affiliate link.
• I don't accept money from the brands whose products I tear down. If a brand sponsorship ever happens, the page will carry a visible "Sponsored" label and the analysis under it won't change. (No brand sponsorships exist as of May 2026.)

The full disclosure language lives on the Legal page, including the exact Amazon Associates Operating Agreement string.

When pages get updated

Each DIY page carries a visible "Updated" date and a matching dateModified in its structured data. Pages are reviewed when:

• A linked bulk-ingredient listing goes out of stock or its price moves more than ~10%.
• A commercial product reformulates — new carb dose, new ratio, new electrolyte profile.
• Significant new peer-reviewed research lands on a topic the page relies on.
• A reader emails us with a correction we can verify.

If you spot an error — in the math, in a citation, in a price, anywhere — please email hello@carbhack.com. Corrections beat opinions.

What this site does not replace

Carb Hack is educational. It is not a substitute for a clinical consultation with a registered dietitian, sports physician, or other qualified healthcare professional. If you have a medical condition, food allergy, eating disorder history, or are pregnant, taking prescription medication, or training for an event with significant cardiovascular load, talk to a real human with a license before changing your fueling. The full medical disclaimer is on the Legal page.