Calculating Macros for Weight Loss
For a person who trains, the goal of weight loss is to lose fat, not muscle. A well-planned calculation of calorie intake and macronutrients helps achieve this. Our editorial team breaks down how to determine the deficit, why you need more protein while dieting than during a bulk, and when a deficit becomes dangerous.
Energy deficit and the pace of weight loss
Fat mass decreases only when energy expenditure exceeds energy intake. So the first step, as during a bulk, is to estimate maintenance calories: using the Mifflin–St Jeor formula with an activity coefficient or, more accurately, by actually tracking food intake 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 falls, energy expenditure falls too, so weight loss slows over time and real results lag behind linear projections.
For athletes the key question is pace. In a study by Garthe and colleagues (2011), elite athletes who lost weight more slowly (about 0.7% of body weight per week) maintained and even increased lean mass, whereas the group losing at about 1.4% per week did not achieve this result.
A review by Helms and colleagues (2014) on preparing natural bodybuilders recommends a pace 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 the person, the slower the pace should be.
Protein: why you need more on a diet
In a state of energy deficit the body uses amino acids as fuel more actively, and muscle protein synthesis declines. That is why 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 substantial deficit with intense training. The group on 2.4 g/kg of protein not only preserved but even gained lean mass and lost more fat than the group on 1.2 g/kg.
Protein has two more useful properties: of all the macronutrients it suppresses hunger the most 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 benchmark 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 calculate from target or lean mass, so as not to get excessive figures.
Fats and carbohydrates under a deficit
Fats should not be cut too sharply: 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 sensible minimum is about 0.6–0.8 g/kg.
Carbohydrates fill the calories remaining after protein and fat. It is they that most affect training quality: glycogen stores determine the ability to perform high-volume work. So when lowering calories it is logical to keep the larger part of carbohydrates around training.
Strict low-carb diets provide no advantage in fat loss at equal calories and protein, but they can worsen strength and speed performance. The choice between a larger share of fat or carbohydrates within the calorie budget is a matter of individual tolerance and convenience.
| Parameter | Bulking | 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, concentrated around training |
Example calculation and risks
A hypothetical woman aged 30, 68 kg, 168 cm tall, training 3–4 times 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 disturbances, reduced bone mineral density, immune suppression, hormonal changes, and worsened performance.
Warning signs are persistent fatigue, a drop in strength, sleep disturbances, the disappearance of menstruation in women, and frequent injuries and illnesses. In that case you need to increase calories and see a doctor. Useful tools for easing a deficit can be refeeds or diet breaks.
Editorial conclusions
Calculating macros for weight loss is built on a moderate deficit, increased protein, and adequate fat; carbohydrates fill the rest of the calorie budget.
A slower pace — 0.5–1% of body weight per week — better preserves muscle and strength, especially in trained and lean people.
The figures from the formulas are only a starting point: adjust the plan by average weight, well-being, and training performance.
We also recommend reading our articles on refeeds and carb cycling, on calculating macros for muscle gain, 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.
