Protein, fat, carbs: how your macros are split

The principle

Once the calorie goal is known, it still has to be split between the three sources of energy: protein, fat and carbohydrates. Azetta doesn't start from percentages. It first sets what your body needs per kilo of body weight — protein and fat, the latter kept within a range of your energy — then gives everything else to carbohydrates, the fuel for training.

The Azetta method

Protein, according to your pace

The value goes up when you are in a deficit: that is when the body is most likely to draw on its muscles.

Fat, per kilo within a range

The starting point is 0.9 g per kilo of body weight. That amount is then kept between 25 % and 35 % of your calorie goal, the range of reference intakes for fat (20 to 35 % of energy according to EFSA and to the joint position of the ACSM, the Academy of Nutrition and Dietetics and Dietitians of Canada on athletes):

Without that range, a big goal left too little fat: for 70 kg gaining weight on a busy 3040 kcal day, 0.9 g/kg gave 63 g, i.e. 19 % of the energy, and 65 % carbohydrates. With the 25 % floor, that same day gives 84 g of fat and 444 g of carbohydrates (58 %). The other way round, a heavy person in a deficit no longer goes over 35 %.

Carbohydrates, to make up the rest

Each gram provides a known amount of energy: 4 kcal for protein and carbohydrates, 9 kcal for fat. Carbohydrates get whatever is left of the goal:

The calculation starts from the goal before it is rounded to the nearest ten, and carbohydrates never go below zero. Each macro is then rounded to the gram.

A training day, more carbs

The day's goal includes the calories of your session (see the article on the calorie goal). Protein depends on your weight, not on your day, and so does fat as long as 0.9 g/kg stays above a quarter of the goal: the extra on a busy day then goes to carbohydrates. Beyond the goal at which 0.9 g/kg is only a quarter of the energy (2592 kcal for 80 kg), each extra kcal goes one quarter to fat and three quarters to carbohydrates. For the man in the example below, a 600 kcal karate session takes a rest day from 2400 to 3000 kcal: protein doesn't move, fat goes from 72 to 83 g and carbohydrates from 311 to 435 g.

Why this choice

• Protein per kilo rather than as a percentage: a percentage drops when calories drop, whereas the need actually rises in a deficit. Reviews on strength training put the useful intake at around 1.6 g/kg per day, and higher when losing weight to preserve muscle.
• Fat per kilo, within a range: 0.9 g/kg guarantees a steady intake, and the 25 to 35 % range of the energy keeps a big goal from squeezing it or a small one from giving it too much room.
• Carbohydrates as the adjustment variable: they are what fuels intense sessions; making them follow the day's expenditure is the simplest way to eat more when you train more.

Limits

• The calculation uses your total weight, not your lean mass: with high body fat, 2 g/kg may be more than necessary.
• There is no target for fibre, sugars, saturated fat or salt: the “Your day” page adds them up for the foods that provide them and compares them with published guidelines (EFSA, WHO), without turning them into targets.
• No split by meal and no timing advice around sessions.
• A reminder appears at the end of the day: from 16:00, if you have eaten less than 80% of your protein, the coach tells you how much you are missing.

References

1. Morton RW, Murphy KT, McKellar SR, et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. British Journal of Sports Medicine, 2018;52(6):376-384.
2. Jäger R, Kerksick CM, Campbell BI, et al. International Society of Sports Nutrition Position Stand: protein and exercise. Journal of the International Society of Sports Nutrition, 2017;14:20.
3. 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;11:20.
4. EFSA Panel on Dietetic Products, Nutrition, and Allergies. Scientific Opinion on Dietary Reference Values for fats. EFSA Journal, 2010;8(3):1461.
5. Thomas DT, Erdman KA, Burke LM. Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic Performance. Journal of the Academy of Nutrition and Dietetics, 2016;116(3):501-528.