How fast should you lose weight on a cut without losing muscle

Cutting at 0.7 per cent of body weight a week means an 85 kg lifter loses about 0.6 kg a week on roughly 650 kcal a day under maintenance. That pace sits in the middle of the range research on lifters supports, 0.5 to 1 per cent a week [1]. Slower keeps more muscle, faster gets you there sooner, and leaner lifters should sit at the slow end. To lose weight on a cut and keep what you built, pick a pace as a share of your weight, then let three weeks of weigh-ins tell you whether you are actually on it.

The cutting calorie calculator turns a pace into a daily target. This guide is about choosing the pace in the first place, what each one costs, and how to check it once the cut has started. Every calorie figure below comes from the same formulas the calculator runs.

The supported range is 0.5 to 1 per cent a week

The pace that keeps the most muscle is a weekly loss of 0.5 to 1 per cent of body weight. That is the recommendation of the main review of natural bodybuilding preparation, which set calories "to maximize muscle retention" at that rate [1]. A later review for physique athletes went further for the end of a contest diet, preferring 0.5 per cent a week or less to limit the loss of fat-free mass [2].

A percentage beats a fixed number of kilos because the cost of a kilo is the same for everyone, but the body carrying it is not. Half a kilo a week is 0.5 per cent of a 100 kg lifter and a much bigger share of a 60 kg one. The second lifter is cutting much harder for the same number on the scale. Set the pace as a share of your weight and the effort scales with you.

The calculator uses 7,700 kcal per kg of loss, so the daily deficit is your weight times the pace times 7,700, divided by 7 days. Each 1 per cent a week costs 110 kcal a day for every 10 kg you weigh, which is why a heavier lifter can run a bigger deficit at the same pace.

What each pace costs an 85 kg lifter

Take an 85 kg man, 180 cm tall and 30 years old, with a low-active day outside the gym. The estimate behind the maintenance calorie calculator puts his maintenance at about 3,020 kcal a day. Here are the three paces for him, with a goal of 78 kg.

The weeks assume the pace is held as a share of his current weight, so the kilos lost each week shrink a little as he gets lighter. Protein stays the same at every pace. If he measured 18 per cent body fat, he would carry about 69.7 kg of lean mass, and 2.3 to 3.1 g per kg of it gives 160 to 216 g a day [1]. The calories that disappear as the pace rises come out of fat and carbohydrate: at 1 per cent a week he eats 204 g of carbohydrate against 290 g at 0.5 per cent.

That difference is what you feel in the gym. Eight weeks shorter sounds good until the last two sets of every session are done on 86 g less carbohydrate a day than the slow plan.

Why does a slower cut keep more muscle?

The best direct test is a trial in 24 elite athletes who lifted four times a week while dieting [3]. One group aimed to lose 0.7 per cent of body weight a week. The other aimed for 1.4 per cent and managed 1.0. Both lost about 5.5 per cent of their weight, the slow group over 8.5 weeks and the fast one over 5.3.

The results split on lean mass. The slow group gained 2.1 per cent lean mass while the fast group's was unchanged, and the slow group lost 31 per cent of its fat mass against 21 per cent [3]. The slow group had cut its energy intake by 19 per cent and the fast group by 30. The authors concluded that athletes who want to add lean mass and 1RM strength during a cut should aim for 0.7 per cent a week.

A meta-analysis of lifting in a deficit points the same way from a different angle. Lifters added less lean mass in a deficit than without one, but their strength rose about as much [4]. Across the studies, a deficit of around 500 kcal a day was enough to stop lean mass increasing, and the authors advise lifters keeping muscle to stay under that [4].

Put that line next to the table. At 0.5 per cent a week, the deficit stays under 500 kcal a day up to about 91 kg of body weight. At 0.7 per cent it stays under up to about 65 kg. So for the 85 kg lifter, the slow pace is the only one of the three that keeps him under the line, by 30 kcal. The line is an average across studies, not a wall, so treat it as a reason to start slow rather than a rule to obey to the calorie.

Strength is the encouraging part. In that meta-analysis, lifting in a deficit raised strength about as much as lifting at maintenance [4]. A cut is no reason to stop chasing the next weight on your top sets, even if the gaps between PRs get longer.

Lean lifters should cut slower

The leaner you are, the slower the pace should be. The physique review prefers 0.5 per cent a week or less when the diet is deep [2], and the energy maths explains part of why.

The 7,700 kcal rule assumes each kilo lost is mostly fat. That holds for people with more than about 30 kg of body fat [5]. For leaner people, a model of weight loss predicts that more of each kilo comes from lean tissue, which holds far less energy than fat, so the same deficit takes weight off faster than the rule says [5]. A lean lifter who sees the scale beat the plan has not found a shortcut. Some of that extra speed is likely to be tissue they wanted to keep.

So the 0.7 per cent default suits a lifter with fat to lose who wants a cut of three months or so. A lifter who is already lean, or deep into a long cut, should drop to 0.5 per cent. The 1 per cent pace suits a heavier lifter with more fat, a short cut, and a reason for speed, such as a weigh-in date. If you are not sure a cut is the right call at all, the cut-or-bulk checker answers that first.

How to check the pace once the cut starts

Check the pace with weekly averages of daily weigh-ins, not single readings, and give it three weeks before changing anything. The first week lies. Stored carbohydrate holds three to four parts water [6], so the scale often drops faster in week one as glycogen falls, then slows down. A lifter who cuts calories again after a slow week two is reacting to water.

Weigh in on waking, after the toilet, before food, as many mornings as you can. Average each week. Compare week three with week one, then divide by two weeks to get the rate.

Here is the adjustment, worked through. Say the 85 kg lifter planned 0.7 per cent a week, about 0.6 kg, and his averages show 0.4 kg a week after three weeks. He is 0.2 kg a week short. At 7,700 kcal per kg, each 0.1 kg a week is worth about 110 kcal a day, so he trims about 220 kcal a day and holds that for another two to three weeks. If he is losing faster than planned instead, he adds food back by the same sum, especially if he is lean.

The other reason the rate slows over a cut is that you are smaller. A lighter body burns less, so the same intake produces a smaller deficit as the weeks go by. Re-running the calculator every few kilos keeps the target honest.

Mistakes that cost muscle on a cut

The first is choosing the pace by the deadline instead of by your body. A summer date does not change how fast a lean lifter can lose fat without losing muscle. If the maths says 17 weeks at the slow pace, starting earlier works better than going faster.

Another is cutting training volume to match the calories. The lifters in the slow group above kept four strength sessions a week and gained lean mass [3]. Keep your working sets and loads where they were for as long as you can recover from them. The volume can come down later if sessions start to fall apart.

A third is chasing the scale day to day. Water and glycogen move the morning number by more than a week of fat loss does. Only the weekly average shows the trend.

Last, lifters skimp on protein to make room for other food. Protein is the one number that should not move with the pace. Our guide to protein for lifters has the ranges and the research behind them.

Questions

How much weight should I lose a week on a cut?

Between 0.5 and 1 per cent of your body weight, which is 0.425 to 0.85 kg a week for an 85 kg lifter [1]. Start at 0.7 per cent if you have fat to lose and about three months to lose it. Drop to 0.5 per cent if you are already lean or late in a long cut, because slower loss keeps more lean mass [2].

Is losing 1 kg a week too fast for a lifter?

For most lifters, yes. A kilo a week is more than 1 per cent of body weight for anyone under 100 kg, which is above the range that research on lifters supports [1]. In elite athletes, the group losing 1.0 per cent a week kept its lean mass flat while a group losing 0.7 per cent gained 2.1 per cent [3].

Why did I lose so much weight in the first week of my cut?

Mostly water. Glycogen, the carbohydrate stored in muscle and liver, is held with three to four parts water [6]. When calories and carbohydrate drop, glycogen falls and the water goes with it, so the first week's loss overstates fat loss. Judge the pace from weeks two and three, using weekly averages of morning weigh-ins.

Will I lose strength if I cut slowly?

Usually not. In a meta-analysis of lifting in a deficit, strength rose about as much as it did without a deficit, even where lean mass grew less [4]. Keep training heavy and keep protein high. A slow cut keeps the deficit small, which leaves more food to train on.