Making the Weight

A planner for combat-sport athletes preparing to make weight.

Live: makingweight.vercel.app

What it does

• Estimates resting metabolic rate (Harris-Benedict) from the athlete's details.
• Splits the planned loss into stages and shows the kilograms each one removes:
  • Fluid: acute body water loss, with 3 to 4% of body mass marked as the safe zone.
  • Gut residue: reducing gut content before the weigh-in.
  • Glycogen: lowering muscle glycogen and the water stored with it (1 g of glycogen binds about 3 g of water).
  • Training camp goal: the fat loss still needed before fight week.
• Flags risk by the total cut as a share of body mass: up to 8% is shown as manageable, over 8% as moderate risk, and over 12% as high risk, with advice to consult a medical professional.

Sources cited in the app: Morton et al. (2010), Harris and Benedict (1919), and Boxing Science.

Use it with care

This is a planning aid for athletes working with qualified practitioners, not medical advice. Rapid weight loss, especially through dehydration, carries real health risks.

Run locally

A single HTML page (with Chart.js from a CDN) that can be installed as a web app. Open index.html, or serve the folder:

python3 -m http.server 8000

Author

Alan Ruddock, exercise physiologist, Sheffield Hallam University, and co-founder of Boxing Science (alanruddock.com).