How fast should you lose fat?
Cut too quickly and a large share of what you lose is muscle. Here is the rate the research supports, and the three things that protect what you built.
Founder of Vertex Strength LabPublished · Updated
Short answer
Aim to lose 0.5 to 1% of your bodyweight per week, usually from a 300 to 500 kcal daily deficit. In elite athletes, cutting at about 0.7% a week kept lean mass and improved strength, while 1.4% a week lost lean mass and stalled strength. Eat 1.8 to 2.4 g/kg of protein and keep lifting heavy.
Everyone wants the fat gone by a date. The problem is that your body does not distinguish between fat and muscle when it needs energy — it distinguishes based on what you are asking it to keep.
The rate of loss is the single biggest lever on what comes off. Get it right and almost all of it is fat. Get it wrong and you finish lighter, weaker, and with a body composition that looks worse than when you started.
0.5–1%
Of bodyweight per week — the rate to hold
2×
How much more lean mass an aggressive cut costs you
The trial that set the number: slow vs fast weight loss
The clearest demonstration (Garthe et al. 2011) compared elite athletes losing weight at roughly 0.7% of bodyweight per week against a group losing at about 1.4% per week. Both groups lifted. Both groups lost similar amounts of fat.
The difference was everything else.
Same fat lost. Very different bodies.
Outcomes in athletes cutting at roughly 0.7% versus 1.4% of bodyweight per week, with resistance training in both groups.
Fat lost
Slow cut · ~0.7%/week · Similar
Fast cut · ~1.4%/week · Similar
Lean mass kept
Slow cut · ~0.7%/week · Kept
Fast cut · ~1.4%/week · Lost
Strength gained during the cut
Slow cut · ~0.7%/week · Up
Fast cut · ~1.4%/week · Flat
The slow group gained lean mass and improved performance while losing fat. The fast group lost fat and lean tissue together, and their strength went nowhere. Twice the speed, half the result you actually wanted.
0.7%
For an 80 kg lifter that is about 560 g a week — roughly a 500 kcal daily deficit. It feels unambitiously slow. It is also the difference between finishing a cut looking leaner and finishing it looking smaller.
What determines your share of fat versus muscle lost
The proportion of weight loss that comes from fat versus lean tissue is not fixed. Three inputs move it, and you control all three.
The same deficit, three different outcomes.
Roughly how weight lost divides between fat and lean tissue depending on how the cut is run.
Deficit onlyno lifting, low protein
70%
fat
30%
lean
Deficit + resistance trainingprotein still low
85%
fat
15%
lean
Deficit + training + high proteinthe full protocol
95%
fat
5%
lean
Notice what the first row means. A pure diet, with no lifting and no protein target, spends nearly a third of your weight loss on the tissue that makes you look and feel the way you wanted to. That is the mechanism behind everyone who has lost 10 kg and been disappointed by the mirror.
The three things that protect muscle
Three inputs. Everything else is detail.
1.8–2.4 g/kg
Protein, higher than usual
Protein requirements go up in a deficit, not down. The leaner you are and the steeper the cut, the closer to the top of that range you should sit.
Keep the loads
Lift heavy, not "for the burn"
Maintaining strength is the signal that tells your body to keep the muscle. Cutting weights and chasing high-rep circuits during a cut is exactly backwards.
300–500 kcal
A modest deficit
Big enough to move, small enough to recover from. Deeper deficits do not accelerate fat loss proportionally — they just take more lean tissue with them.
You can reduce training volume somewhat in a deficit — recovery is genuinely impaired — but you should not reduce load. Keep the intensity, trim a set or two per muscle if you need to.
The scale will lie to you
Weight moves for reasons that have nothing to do with fat. Glycogen and its associated water, sodium, menstrual cycle, digestive contents, and the delayed water retention that follows a hard session all swamp a week's genuine fat loss.
"I've been perfect for five days and the scale hasn't moved."
Too few data points
Weigh daily, average weekly, judge fortnightly. If the seven-day average has not moved in two weeks, then adjust — by about 200 kcal, not by starting again.
When to stop: how long a cut should last
Cuts should have an end date. Prolonged deficits reduce training performance, hormone levels and adherence, and the returns fall as you get leaner.
Run a cut for 8 to 16 weeks, then spend a few weeks eating at maintenance before deciding whether to go again. That break is not lost progress — it restores training quality and makes the next block work.
Key numbers
| What | Target |
|---|---|
| Rate of loss | 0.5–1% of bodyweight per week |
| Daily deficit | 300–500 kcal |
| Protein | 1.8–2.4 g/kg |
| Training | Keep the loads, trim a set or two if needed |
| Length of a cut | 8–16 weeks, then a few weeks at maintenance |
| When to adjust | Seven-day average flat for two weeks: about 200 kcal less |
The short version
Aim for 0.5 to 1% of bodyweight per week. Eat 1.8–2.4 g of protein per kilogram (Helms et al. 2014; Jäger et al. 2017). Keep lifting heavy, keep the loads on the bar, and take a modest deficit rather than a heroic one.
The fast cut and the slow cut both get you lean. Only one of them leaves you with the physique you were cutting to reveal.
Common questions
How much fat can I lose in a week?
Aim for 0.5 to 1% of bodyweight per week. For an 80 kg person at 0.7%, that is about 560 g a week, roughly a 500 kcal daily deficit.
Will I lose muscle in a calorie deficit?
Some lean loss is likely if you diet without lifting or enough protein. A modest deficit, heavy resistance training and 1.8 to 2.4 g/kg of protein keep the share of weight lost from lean tissue small.
Why has the scale not moved this week?
Water, glycogen, sodium, gut contents and the menstrual cycle move daily weight by 1 to 2 kg. Weigh daily, compare seven-day averages week to week, and only adjust if the average is flat for two weeks.
Should I lift lighter weights for more reps when cutting?
No. Keeping the loads on the bar is the signal that tells your body to keep the muscle. Trim volume slightly if recovery suffers, but not the load.
How long should a cut last?
8 to 16 weeks, followed by a few weeks at maintenance before deciding whether to go again. Prolonged deficits erode training performance, hormone levels and adherence.
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;21(2):97–104. doi:10.1123/ijsnem.21.2.97
- 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;11(1). doi:10.1186/1550-2783-11-20
- Jäger R, Kerksick CM, Campbell BI, Cribb PJ, Wells SD, Skwiat TM, et al. International Society of Sports Nutrition Position Stand: protein and exercise. Journal of the International Society of Sports Nutrition. 2017;14(1). doi:10.1186/s12970-017-0177-8