How Fast Should You Actually Lose Weight?
Faster isn't better past a point, and the point is measurable. Garthe and colleagues put athletes on either a slow or a fast deficit to reach the same body composition target: both groups lost the weight, but the slower group retained more lean mass and improved strength while the faster group didn't. The commonly cited ceiling is around 1% of bodyweight per week, with roughly 0.5-0.7% being the range where lean tissue is best preserved. Two things make a fast deficit more survivable: keeping protein high, and continuing to train hard enough to give your body a reason to hold onto muscle.
Neither fully removes the cost. Heavier people can generally sustain the upper end of that range more comfortably than lean people, because there's more fat mass available to draw on.
Kriterion tells you what a given rate will cost you before you pick it, then does the maths for the pace you chose rather than the one it would have chosen.
References
- 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, 2011.
- Helms ER, Aragon AA, Fitschen PJ. Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementation. Journal of the International Society of Sports Nutrition, 2014.
- Murphy C, Koehler K. Energy deficiency impairs resistance training gains in lean mass but not strength: a meta-analysis. Scandinavian Journal of Medicine & Science in Sports, 2022.
Kriterion is the app this reasoning is built into
It measures your maintenance calories from what you actually ate against what the scale actually did, tells you how firmly the number is pinned down, and checks its own past predictions against your results. Free logging, UK food data, and no ads.
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