Bulk and cut rate checker: am I on target?

On a bulk you want to gain, but not too fast. On a cut you want to lose, but not in a rush. The scale alone cannot tell you, because it moves every day. Enter your weigh-ins: the calculator takes your rate from your trend weight and compares it with the range you set for yourself.

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Order and separators don't matter, comma or dot as decimal mark. Several weigh-ins on the same day are averaged.

Drop a file here or

Apple Health (export.zip or export.xml), Withings (weight.csv or ZIP), Google Fit (Takeout CSV), Happy Scale, Libra, openScale, Trendcurve and any CSV with a date and a weight column.

Target range per week

Default 0.25 to 0.5% per week: a guide for novice and intermediate lifters from Iraki et al. 2019. Change it freely.

Your rate Example data

This is made-up example data covering twelve weeks, so you can see what a result looks like. Paste your own weigh-ins above.

Rate per week
Your target range
Result
Estimated energy balance
Daily weigh-ins (noise) Trend Target range

Estimated with 7,700 kcal per kilogram, as in the Trendcurve app. That figure applies to fat tissue. Muscle gain works differently: new muscle is mostly water and stores less energy per kilogram, but building it costs energy itself. On a bulk the number is only a rough direction.

Every day, automatically: Trendcurve for iPhone and Android

The app reads your weight from Apple Health or Health Connect and shows your trend and 7-day change, no copying and pasting. Free, no account, your weigh-ins stay on your device.

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Your rate from the trend, every day

Trendcurve recalculates your trend after every weigh-in and shows your weekly rate for free. That includes a gain, lose or maintain goal with a target rate and a rate warning. With Pro you see planned versus measured and the calorie budget from your measured weekly rate.

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How fast should you gain on a bulk and lose on a cut?

If you want to build muscle, you eat a bit more than you burn. If the surplus is too small, little happens. If it is too large, you mainly add fat. On a cut it is the other way round: too slow costs months, too fast puts your muscle at risk. That is why many people plan with a rate instead of a calorie number, usually in percent of body weight per week.

The problem: the scale moves more from day to day than you want to gain or lose in a week. A single reading says almost nothing about your rate. Trend weight smooths out water, salt and digestion, and the slope of the trend over two to four weeks shows how fast you are really moving.

Where the defaults come from

  • Cut: 0.5 to 1% of body weight per week. Helms, Aragon and Fitschen (2014) recommend this in a review on contest preparation in natural bodybuilding, to retain as much muscle as possible.
  • Bulk: 0.25 to 0.5% of body weight per week. Iraki, Fitschen, Espinar and Helms (2019) give this range in a narrative review for novice and intermediate lifters. According to the same paper, advanced athletes should gain more conservatively.
  • Maintain: ±0.1 kg per week. This is not a study recommendation but the threshold below which the Trendcurve app calls it a plateau.
  • All three are only starting points. You can set any range freely, in percent or in kg or lb per week.

How the calculator works

  1. Your weigh-ins become a trend weight with exponential smoothing, exactly as in the Trendcurve app.
  2. The rate is the slope of a regression line through the trend values of the last 14 days, like the weekly rate in the app. You can also use 28 days, which smooths more.
  3. The percentage refers to your current trend weight. At 80 kg (176 lb), 0.25 to 0.5% means 0.2 to 0.4 kg (0.44 to 0.88 lb) per week.
  4. In the chart the range starts at the trend value at the beginning of the period. If the green line stays inside the band, you are on plan.
  5. The energy balance is the rate divided by 7, times 7,700 kcal per kilogram: a trend of plus 0.3 kg per week equals roughly 330 kcal surplus per day.

How to get a reliable result

  • Weigh yourself daily if you can, at the same time, ideally in the morning after the bathroom. The calculator needs at least four weigh-ins in 14 days.
  • At the start of a bulk or a cut, glycogen and water shift first. The first week therefore often shows a rate that has nothing to do with fat or muscle. Wait one to two weeks.
  • Creatine, a lot of salt or a change in carbohydrates also shift water. Afterwards, prefer the 28-day period.
  • The scale measures weight, not muscle. Whether the gain is muscle or fat is better shown by your waist, photos and strength numbers.

Sources

  1. Helms ER, Aragon AA, Fitschen PJ. Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementation. J Int Soc Sports Nutr 2014;11:20. doi.org/10.1186/1550-2783-11-20 · PubMed
  2. Iraki J, Fitschen P, Espinar S, Helms E. Nutrition Recommendations for Bodybuilders in the Off-Season: A Narrative Review. Sports (Basel) 2019;7(7):154. doi.org/10.3390/sports7070154 · PubMed

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Frequently asked questions

There is no fixed number. A narrative review by Iraki and colleagues (2019) gives about 0.25 to 0.5% of body weight per week for novice and intermediate lifters, and less for advanced lifters. At 80 kg (176 lb) that is 0.2 to 0.4 kg (0.44 to 0.88 lb) per week. The calculator uses this range as its default, and you can change it freely.

For contest preparation in natural bodybuilding, Helms and colleagues (2014) recommend about 0.5 to 1% of body weight per week to retain as much muscle as possible. The Trendcurve app warns when the target rate or the measured rate is above 1% per week.

Daily weight often swings by more than a kilo (2 lb) through water, salt and digestion. On a bulk, though, you may only want to gain 0.3 kg (0.7 lb) a week. Trend weight smooths out the swings, and only its slope over two to four weeks shows your real rate.

It uses 7,700 kcal per kilogram, like the Trendcurve app. That fits fat tissue well, so mainly a cut. Muscle gain works differently: muscle stores less energy per kilogram, but building it costs extra energy. On a bulk the number is only a rough direction.

When you eat more, you first store more glycogen and water; when you eat less, you lose both. That moves the scale quickly without much change in muscle or fat. Wait one to two weeks after starting before you judge your rate.

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More on rate, calories and water on the blog