Healthy Race Weight Planner: free safe weight loss calculator.
Enter your weight, your goal and the weeks to your race. Get a safe weekly pace, or an honest no.
A safe pace
A week
0.25kg
0.3% of your weight a week. The planner never goes past 0.7% a week or a 500 kcal daily deficit, and keeps energy availability at 30 or more.
Garthe 2011ACSM 2016To lose by race day
3.0kg
Over 12 weeks. The fastest the planner would go for you is 0.3 kg a week.
Daily deficit
280kcal
About 7,700 kcal per kg lost, a rough rule that overestimates loss over time.
Wishnofsky 1958Energy availability at this deficit: about 30.1 kcal per kg of fat free mass, at or above the 30 line. Mountjoy 2023Jeukendrup 2024
The research says lose weight in base training, well away from your race, and keep fueling your key sessions. Your AI can adjust this to your training. ACSM 2016
Hand it to your AI
Your AI can check these numbers against your training and adjust them. The prompt has your results filled in.
See the prompt
I weigh 80 kg and I'm thinking about racing at 77 kg in 12 weeks. A race weight planner built on the research (at most 0.7% of body weight a week, Garthe 2011; a 250 to 500 kcal deficit, ACSM 2016) says that is about 0.3 kg a week, a deficit of about 280 kcal a day. Look at my training, fueling and recovery, and tell me honestly whether losing weight before this race is worth it, and how to do it without hurting my training. If I shouldn't, say so.
Gemini, Grok Bot, Dots, Muse and Cue: copy the prompt and paste it in.
Your AI could check this against your real training. Join Memory.fit.
On Android now: get it on Google Play. One email when the iPhone app is on the App Store.
How it works
How the Healthy Race Weight Planner works.
Losing weight while you train is a trade: every calorie you cut is one your training and recovery don't get. So the planner keeps the loss slow. In a trial with elite athletes, losing about 0.7% of body weight a week kept strength and power better than losing faster, so 0.7% a week is its ceiling. The ACSM position stand adds a deficit of 250 to 500 kcal a day, taken from your needs for that day, ideally in base training.
If your goal fits in the weeks you have at that pace, you get the pace and the daily deficit. If it doesn't, you get what you could reach by race day and how long the full goal would take.
It refuses to plan in four cases: a goal under a BMI of 18.5, a body that is already there, a deficit that would take energy availability below about 30 kcal per kg of fat free mass (when you give your body fat), and pregnancy or breastfeeding, when energy needs go up. Turning kilograms into calories uses the rough rule of 7,700 kcal per kg, which overestimates loss over time, so your real trend beats the plan.
The formula
- weekly pace = what you need to lose ÷ weeks, at most 0.7% of body weight
- daily deficit = weekly pace × 7,700 ÷ 7, at most 500 kcal
- energy availability check = (resting energy × daily life − deficit) ÷ fat free mass ≥ 30
The science
Where the numbers come from.
Every number on this page links to the paper it comes from. How Memory.fit uses the science
Garthe I, Raastad T, Refsnes PE, Koivisto A, Sundgot-Borgen J. Effect of two different weight-loss rates on body composition and strength and power-related performance in elite athletes. International Journal of Sport Nutrition and Exercise Metabolism 21(2):97-104.
Randomized trial · 2011 · doi:10.1123/ijsnem.21.2.97
Thomas DT, Erdman KA, Burke LM. American College of Sports Medicine Joint Position Statement. Nutrition and Athletic Performance (2016). Medicine & Science in Sports & Exercise 48(3):543-568.
Position stand · 2016 · doi:10.1249/MSS.0000000000000852
Mountjoy M, Ackerman KE, Bailey DM, et al. 2023 International Olympic Committee's (IOC) consensus statement on Relative Energy Deficiency in Sport (REDs). British Journal of Sports Medicine 57(17):1073-1097.
Consensus statement · 2023 · doi:10.1136/bjsports-2023-106994
Wishnofsky M. Caloric equivalents of gained or lost weight (1958). The American Journal of Clinical Nutrition 6(5):542-546.
Study · 1958 · doi:10.1093/ajcn/6.5.542
Hall KD. What is the required energy deficit per unit weight loss? (2008). International Journal of Obesity 32(3):573-576.
Study · 2008 · doi:10.1038/sj.ijo.0803720
Example
A worked example.
A 40 year old man, 180 cm and 80 kg with 18% body fat, who wants to race at 77 kg in 12 weeks.
- 1He wants to lose 3 kg in 12 weeks: 0.25 kg a week, or 0.3% of his weight. That is under the 0.7% ceiling.
- 20.25 kg a week × 7,700 ÷ 7 = a deficit of about 280 kcal a day, inside the 250 to 500 range.
- 3His fat free mass is about 65.6 kg. At that deficit his energy availability is about 30, right at the line, so the planner accepts it. A goal of 74 kg in the same time would not fit, and the planner would say so.
Questions
Healthy Race Weight Planner: questions.
Slow. A trial in elite athletes found about 0.7% of body weight a week kept strength and power better than faster loss. The ACSM position stand suggests a deficit of 250 to 500 kcal a day.
The weight you'd like to race at. Lighter is not always faster: arriving well fueled and recovered matters more than the last kilogram.
Because the goal is below a BMI of 18.5, the loss would take energy availability too low, you're pregnant or breastfeeding, or there is nothing to lose. In each case the safe answer is no plan.
The research says do it in base training, well away from your race, and keep fueling your key sessions. Close to a race, fueling for performance usually matters more.
No. Energy needs go up in pregnancy and while breastfeeding, so the planner makes no weight loss plan. Talk to your midwife or doctor.
Not medical advice. These numbers come from published research on groups of athletes. Your own needs can differ; talk to a doctor or a sports dietitian about any health condition.