Calculating Macros for Weight Loss
The goal of weight loss for a person who trains is to lose fat, not muscle. A well-judged calculation of calorie intake and macronutrients helps achieve this. The editorial team breaks down how to determine the deficit, why more protein is needed during a diet than during a gaining phase, and when a deficit becomes dangerous.
Energy deficit and the rate of weight loss
Fat mass decreases only on condition that energy expenditure exceeds energy intake. So the first step, as with gaining mass, is estimating maintenance calorie intake: using the Mifflin–St Jeor formula with an activity coefficient or, more accurately, by actual food tracking at a stable weight.
The popular rule 'minus 500 kcal a day — minus half a kilogram a week' turned out to be too simplistic. The model by Hall and colleagues (2011), published in The Lancet, showed that as weight decreases, energy expenditure also falls, so weight loss slows over time and real results lag behind linear forecasts.
For athletes the key question is the rate. In a study by Garthe and colleagues (2011), elite athletes who lost weight more slowly (about 0.7% of body weight per week) preserved and even increased lean mass, whereas a group with a rate of about 1.4% per week did not achieve such a result.
The review by Helms and colleagues (2014) on the preparation of natural bodybuilders recommends a rate of 0.5–1% of body weight per week. In practice this usually corresponds to a deficit of 15–25% of maintenance calories. The leaner a person is, the slower the rate should be.
Protein: why there's more of it on a diet
In a state of energy deficit the body uses amino acids as fuel more actively, and muscle protein synthesis decreases. Therefore the need for protein increases during weight loss. The systematic review by Helms, Zinn, Rowlands and Brown (2014) proposed a range of 2.3–3.1 g per kilogram of lean mass for lean, trained athletes in a deficit.
A telling study by Longland and colleagues (2016): young men spent four weeks in a significant deficit with intense training. The group with 2.4 g/kg of protein not only preserved but even gained lean mass and lost more fat than the group with 1.2 g/kg.
Protein has two more useful properties: it curbs hunger more strongly than any other macronutrient and has the highest thermic effect — more energy is spent on its digestion. Both factors make it easier to stick to a diet.
A practical guideline for most people who train is 1.8–2.4 g/kg of total body weight. People with a large excess of fat find it more convenient to count from target or lean mass so as not to get excessive figures.
Fats and carbohydrates under a deficit
Fats shouldn't be cut too drastically: they are needed for the synthesis of sex hormones and the absorption of fat-soluble vitamins. Helms and colleagues (2014) recommend 15–30% of calories from fat during preparation. For most people a reasonable minimum is about 0.6–0.8 g/kg.
Carbohydrates fill the calories remaining after protein and fats. It is precisely they that most affect the quality of training: glycogen stores determine the ability to perform high-volume work. Therefore, when reducing calorie intake it is logical to keep the larger part of carbohydrates around training.
Strict low-carbohydrate diets give no advantage in fat loss at equal calorie intake and protein, but can worsen strength and speed performance. The choice between a larger share of fats or carbohydrates within the calorie budget is a question of individual tolerance and convenience.
| Parameter | Gaining mass | Weight loss |
|---|---|---|
| Energy | Surplus ~10–20% | Deficit ~15–25% |
| Rate of weight change | +0.25–0.5% per week | −0.5–1% per week |
| Protein | 1.6–2.2 g/kg | 1.8–2.4 g/kg (higher for lean individuals) |
| Fats | 20–35% of calories | 15–30% of calories |
| Carbohydrates | The rest, priority to training | The rest, concentrate around training |
Example calculation and risks
A hypothetical woman aged 30, 68 kg, 168 cm tall, 3–4 workouts a week. Basal metabolic rate: 10 × 68 + 6.25 × 168 − 5 × 30 − 161 = 1419 kcal. With a coefficient of 1.5, maintenance is about 2130 kcal. A 20% deficit gives a target of about 1700 kcal.
- Protein: 2.0 g × 68 = 136 g → 544 kcal;
- Fats: 0.8 g × 68 ≈ 54 g → ~490 kcal;
- Carbohydrates: (1700 − 544 − 490) / 4 ≈ 165 g → ~665 kcal.
An excessive deficit is dangerous. The IOC consensus on relative energy deficiency in sport (RED-S, Mountjoy and colleagues, 2018) describes the consequences of chronic energy shortage: menstrual cycle disruption, decreased bone mineral density, immune suppression, hormonal changes, impaired performance.
Warning signs are constant fatigue, a drop in strength, sleep disturbances, the disappearance of menstruation in women, frequent injuries and illnesses. In that case you need to increase calorie intake and see a doctor. Refeeds or diet breaks can be useful tools for easing a deficit.
Editorial conclusions
Calculating macros for weight loss is built on a moderate deficit, increased protein and a sufficient amount of fats; carbohydrates fill the rest of the calorie budget.
A slower rate — 0.5–1% of weight per week — better preserves muscle and strength, especially in trained and lean people.
The figures from formulas are only a start: adjust the plan according to average weight, well-being and training performance.
We also recommend reading our articles on refeeds and carbohydrate cycling, on calculating macros for gaining mass and on fiber in an athlete's diet.
References
- Hall KD, Sacks G, Chandramohan D, et al. Quantification of the effect of energy imbalance on bodyweight. Lancet. 2011;378(9793):826–837.
- Garthe I, Raastad T, Refsnes PE, et al. Effect of two different weight-loss rates on body composition and strength and power-related performance in elite athletes. Int J Sport Nutr Exerc Metab. 2011;21(2):97–104.
- 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.
- Helms ER, Zinn C, Rowlands DS, Brown SR. A systematic review of dietary protein during caloric restriction in resistance trained lean athletes: a case for higher intakes. Int J Sport Nutr Exerc Metab. 2014;24(2):127–138.
- Longland TM, Oikawa SY, Mitchell CJ, et al. Higher compared with lower dietary protein during an energy deficit combined with intense exercise promotes greater lean mass gain and fat mass loss: a randomized trial. Am J Clin Nutr. 2016;103(3):738–746.
- Mountjoy M, Sundgot-Borgen JK, Burke LM, et al. IOC consensus statement on relative energy deficiency in sport (RED-S): 2018 update. Br J Sports Med. 2018;52(11):687–697.
Andriy Melnyk
A strength-sports coach and author of programs for beginner and intermediate levels. Writes about training planning.
