The science behind the FUEL Calculator

The science behind the FUEL Calculator.

Every coefficient, anchored to peer-reviewed research.

The FUEL Calculator returns a personalized post-workout carbohydrate and protein target for the first 60–90 minutes after training. Every multiplier in the formula traces back to peer-reviewed sports nutrition literature, primarily the ISSN 2017 Nutrient Timing Position Stand.

What the calculator returns

• Carbs (grams) — your target carbohydrate intake across the recovery window.
• Protein (grams) — your post-workout protein dose.
• Window (minutes) — the recommended ingestion timing range.
• Window status — OPEN (refuel right now), ACTIVE (within the next 60–90 minutes), or WIDE (across the next 1–3 hours).
• Pouch count — how many Gummy Gainz pouches deliver those numbers.

The carbohydrate number is the target across the window, not a single bolus. A 75 kg endurance athlete on a tournament day shows a 117 g carb target — that's roughly 1.2 g/kg/hr across the recovery window, which lands inside Burke et al.'s (2017) recommended glycogen restoration rate for the first four hours after training.

Protein dose

0.3 g/kg of body weight, capped at 40 g, with multipliers for age and sport.

• The 0.3 g/kg coefficient sits in the middle of the ISSN 2017 recommendation of 0.25–0.40 g/kg per post-workout dose [Kerksick 2017].
• Masters athletes (35+) get a 1.15× multiplier to overcome anabolic resistance [Moore 2015].
• Youth athletes (under 18) get a 1.10× multiplier to account for growth and maturation.
• The 40 g ceiling reflects practical reality for a gummy product: hitting 60 g+ of protein means consuming 230 g+ of accompanying carbohydrates, which causes osmotic GI distress before it helps recovery [Macnaughton 2016].

Carb target

Scaled to body weight, sport, session duration, age, and competition schedule.

• Endurance athletes anchor at 1.2 g/kg, matching the ISSN and IOC consensus of 1.0–1.2 g/kg/hr for rapid glycogen restoration [Kerksick 2017, Burke 2017].
• Strength and power athletes anchor at 0.8 g/kg because a typical strength session depletes only 25–40% of muscle glycogen [MacDougall 1999].
• Youth athletes get a 0.9× multiplier because prepubertal athletes rely more on fat oxidation and less on muscle glycogen than adults [Timmons 2003].
• Tournament days and two-a-days get a 1.3× and 1.2× multiplier respectively, scaling the post-workout dose to support the elevated 8–10+ g/kg daily total typical of multi-bout schedules [Burke 2017].

Timing window

• Fasted training → WINDOW: OPEN (20–60 min). Empty stomach pre-training means glycogen is depleted and amino acid availability is low, so prompt refueling matters [Aragon & Schoenfeld 2013].
• Fed training → WINDOW: WIDE (60–180 min). A pre-workout meal 2–3 hours prior is still digesting, so the post-workout window extends to three hours or more [Aragon & Schoenfeld 2013].
• Tournament or two-a-days override. When the next performance is less than 8 hours away, rapid refueling becomes critical regardless of fed state [Burke 2017].

Citations

Primary dosing and timing

• Kerksick, C. M., et al. (2017). International society of sports nutrition position stand: nutrient timing. Journal of the International Society of Sports Nutrition, 14(33). doi:10.1186/s12970-017-0189-4
• Aragon, A. A., & Schoenfeld, B. J. (2013). Nutrient timing revisited: is there a post-exercise anabolic window? Journal of the International Society of Sports Nutrition, 10(5). doi:10.1186/1550-2783-10-5
• Burke, L. M., et al. (2017). Carbohydrates for training and competition. Journal of Sports Sciences, 35(sup1), 17–27. doi:10.1080/02640414.2016.1210197

Age-specific modifiers

• Timmons, B. W., et al. (2003). Oxidation rate of exogenous carbohydrate during exercise is higher in boys than in men. Journal of Applied Physiology, 94(1), 278–284. doi:10.1152/japplphysiol.00696.2002
• Moore, D. R., et al. (2015). Protein ingestion to stimulate myofibrillar protein synthesis requires greater relative protein intakes in healthy older versus younger men. The Journals of Gerontology Series A, 70(1), 57–62. doi:10.1093/gerona/glu103

Dose ceilings and glycogen depletion

• MacDougall, J. D., et al. (1999). Muscle glycogen depletion during weight resistance exercise. Journal of Applied Physiology, 86(5), 1704–1709. doi:10.1152/jappl.1999.86.5.1704
• Jeukendrup, A. (2014). A step towards personalized sports nutrition: carbohydrate intake during exercise. Sports Medicine, 44(Suppl 1), 25–33. doi:10.1007/s40279-014-0148-z

What this calculator is not

• It is not a daily meal plan. It returns one post-workout target, not a 24-hour intake.
• It is not a medical recommendation. Athletes with metabolic conditions, GI disorders, or competing dietary protocols should consult a sports dietitian.
• It is not specific to Gummy Gainz. Any food source delivering the recommended carbohydrate and protein in the window works. Gummy Gainz is one option engineered to land the 3.7:1 ratio in a portable, heat-stable form.

written with sports dietitians, not for them.