A moderate pace, high protein, strength training kept intact — and a floor that is not negotiable. The route that protects strength and recovery.
The honest answer first: it works — but only slowly, with plenty of protein, and with a floor you do not go below. Three dials decide whether your body fat drops while your performance stays: the pace, the protein, and whether your strength training carries on untouched.
The one number worth memorising is not a calorie number, it is a protein number. The position stand of the International Society of Sports Nutrition names 2.3 to 3.1 g of protein per kilogram of body weight per day for trained individuals in a diet phase, to preserve fat-free mass [1]. In a deficit your protein requirement rises — it does not fall.
And one sentence that matters more here than any method: if too little energy is left over for everything your body does outside training, you lose performance first, then bone density and hormonal function [2]. So this guide is not a manual for losing weight fast. It is a manual for reducing body fat without wrecking the thing you train for.
A diet phase costs energy, focus and patience. During hard competition preparation, in a stressful period of life, on poor sleep or straight after an injury, it is almost always the wrong decision.
And one more honest filter: if food currently occupies you more than your training, if you skip meals to stay "clean", or if your body image is putting you under pressure — then this guide is not your next step. Then it is a conversation with your doctor, a registered dietitian, or an eating disorder counselling service. That is not a retreat, it is the professional route.
Estimate your requirement with the Mifflin-St Jeor equation: 10 × kg + 6.25 × cm − 5 × age, plus 5 for men, minus 161 for women [3], times an activity factor. In practice people then run a moderate minus in the region of 300 to 500 kcal a day — an experience value from counselling practice, not a study figure and explicitly not a prescription.
Why not more? Because the estimate itself is imprecise: Mifflin-St Jeor hits measured resting metabolic rate within ±10 % more often than any other equation [4] — at 2,400 kcal that is around 240 kcal of uncertainty. Building an aggressive deficit on a wobbly number is the fastest way to end up far too low by accident.
The better dial is not the scale anyway, it is your performance. If training loads and recovery stay stable, the pace is right. If they collapse, it is too fast — whatever the scale says.
Protein is the last item you economise on. 2.3 to 3.1 g/kg per day for trained individuals in a diet phase [1] sounds like a lot, and it is — at 75 kg that is 170 to 230 g. Anyone who cannot reach that range is still far better off at the upper end of the general 1.4 to 2.0 g/kg band [1] than on typical diet fare.
Spread the amount across at least four meals at roughly 0.4 g/kg per meal [5]. What gets cut is fat, and the carbohydrates that do not sit around training. The carbohydrates before and after a hard session are what carries your performance through a deficit at all.
The most common mistake in a diet phase is doing more cardio and training heavier at the same time. That combination rarely ends well.
Keep the intensity high — the loads — and if in doubt take something out of the volume. The heavy stimulus is the signal to your body to hold on to muscle. Extra cardio is rarely the lever it promises to be: mostly it enlarges the very deficit you wanted to keep moderate.
There is a point at which a diet stops being a diet. The IOC consensus statement on relative energy deficiency describes low energy availability as a spectrum from adaptable to problematic, with a widely cited orientation threshold of below 30 kcal per kilogram of fat-free mass per day in women; in men the data are blurrier and the range sits lower [2].
These warning signs mean: stop, do not grind through.
If one of these shows up clearly, the diet phase is over — and the next step is an appointment, not a further cut.
If you would rather not do the arithmetic yourself: the nutrition plan in the Lab uses the same equation and has a floor built in. That too remains an estimate and replaces no advice.
This guide informs, it does not replace medical or dietetic advice and makes no diagnosis. With pre-existing conditions, during pregnancy and breastfeeding, with diabetes, thyroid or cardiovascular disease, or while taking medication, any deliberate weight reduction belongs under medical supervision.
A missing cycle, recurring infections, bone pain or bone stress reactions are medical warning signs, not signs of good preparation [2]. Please have them checked medically rather than training through them.
If eating, counting, weighing or controlling increasingly runs your day, if you skip meals out of fear, or if the thought of a break from dieting makes you panic: talk to your doctor, a qualified dietitian, or an eating disorder counselling service. Diet phases of this kind are not intended for growing children and adolescents.
During a diet phase, run a performance traffic light instead of a second calorie tracker. Three values, noted once a week: your most important training load, your average hours of sleep, and how you feel during the warm-up (green, amber, red).
The reason: in the short term the scale lies almost every time — through water, salt and cycle. Your performance does not lie. Two amber weeks in a row mean: ease off. That gives you a dial that protects you before warning signs appear — and turns a diet into a training project rather than a project of going without.
Slowly enough that your training performance stays stable — that is a better yardstick than any weekly number on the scale. In practice that means a moderate deficit across weeks, not days. If training loads, sleep and recovery fall away, the pace is too fast, regardless of what the scale says.
Because less energy arrives than your body needs for training, recovery and all remaining functions. If too little is left, resting metabolic rate, the hormonal system, bone metabolism and strength performance are among the things that react [2]. A moderate pace, enough carbohydrates around training and enough sleep absorb most of it.
More than usual. For trained individuals in hypocaloric phases the ISSN position stand names 2.3 to 3.1 g per kilogram of body weight per day to preserve fat-free mass [1]. Spread the amount across at least four meals at roughly 0.4 g/kg [5] rather than trying to catch up in the evening.
By a pattern, not a single symptom: falling training loads, constantly feeling cold, poor sleep, frequent infections, a missing or irregular cycle, loss of libido, irritability [2]. If several of these come together, the diet phase is finished and the next step is a medical check.
For beginners, returners and at higher body fat levels it is realistic; for advanced trainees it is rare. That is practical experience, not a proven rule. The more realistic goal in a deficit is to keep the muscle you have — which is exactly what high protein [1] and heavy strength training are for.
Under-Fuelling: The Problem Nobody Talks About (REDs)