How to Calculate Macros for Weight Loss

Macros for weight loss are the grams of protein, carbohydrate and fat that make up a daily energy target set below what your body uses. To work them out, estimate your daily energy needs at a healthy weight as your target, split it by percentage, then divide each share by its kilojoules per gram: 17 for protein and carbohydrate, and 37 for fat.

This is general information, not medical advice. Energy needs and rates of weight loss vary between individuals, and a GP or accredited practising dietitian can help you set targets that suit your health.

On this page

1. What Are Macros?
2. How to Calculate Your Macros for Weight Loss
3. Check Your Protein
4. Is There a Best Macro Split for Weight Loss?
5. Choosing Foods for Each Macro
6. Macros, Movement and Muscle
7. Tracking Your Progress
8. Who Should Get Advice First
9. When Diet and Activity Are Not Enough
10. Frequently Asked Questions

What Are Macros?

Macros is short for macronutrients: the three nutrients your body needs in large amounts, and the three that supply most of the energy in food.

• Protein helps every cell in your body grow, repair and stay healthy, and gives structure to tissues such as muscle. It is found in lean meat, poultry, fish, eggs, dairy foods, nuts, seeds and legumes.

• Carbohydrates are the body's preferred energy source and fuel the brain, nervous system and kidneys. They come as sugars, starch and fibre, in foods such as wholegrains, legumes, fruit and vegetables.

• Fat is part of a nutritious diet, and the type and amount matter. It is the most energy-dense macro, with more than double the kilojoules per gram of protein or carbohydrate.

Each macro carries a set amount of energy per gram. Australian food labels use kilojoules; many apps use calories, so the table gives both.

Alcohol also supplies energy, 29 kJ per gram, but it is not counted as a macro because the body does not need it. The calorie figures are the kilojoule figures divided by 4.2 and rounded, which is why most apps show 4, 4 and 9.

How to Calculate Your Macros for Weight Loss

Working out your macros takes four steps. The first two set your daily energy target; the last two split that target into grams.

Step 1: Estimate your daily energy target

The average adult needs about 8,700 kJ (about 2,070 calories) a day, but needs vary with age, sex, height, weight, muscle and how active you are (healthdirect). For a personal estimate, use the free daily energy requirements calculator on the Australian Government's Eat for Health website. If you are aiming to lose weight, its instructions say to enter your ideal body weight rather than your current weight, which gives a lower estimated energy requirement. That figure is your daily target.

Step 2: Check the gap and the floor

Weight changes with total energy, whatever mix of macros it comes from: eat more kilojoules than you use and weight goes up, whether they come from fat, carbohydrate or protein. So the energy target sets the direction, and the macro split shapes the diet within it.

Your target sits below what your body uses now: run the calculator again with your current weight to see the gap. The Australian Obesity Management Algorithm (2024), a guide for primary care, puts a modest energy deficit at about 2,000 to 4,000 kJ a day (about 480 to 960 calories), together with more physical activity. That range describes the size of the gap. It is not a further cut from your target. Then check the target: a good weight management service will advise against a daily intake below 5,000 kJ (1,200 calories). If your target falls below that, talk to a GP or dietitian first.

Got your numbers? If you want a doctor to look at your weight plan as a whole, check whether you are eligible for a medical weight loss plan. Online, no appointment needed.

Step 3: Choose a split inside the Australian ranges

Australia and New Zealand's Nutrient Reference Values set acceptable ranges for how much of your daily energy comes from each macro:

These ranges are set for otherwise healthy adults eating to keep their weight steady. The Nutrient Reference Values say they are not necessarily recommendations for the best weight loss diet, or for managing an existing health condition. Treat them as a sensible frame, not a formula. Pick percentages that add up to 100 and suit how you like to eat.

Step 4: Turn percentages into grams

Multiply your daily target by each percentage to get the kilojoules for that macro. Then divide by that macro's kilojoules per gram, from the table in "What Are Macros?".

A worked example

Take a woman aged 31 to 50, 1.6 m tall, with seated work. The Nutrient Reference Values (Eat for Health) put her energy needs at a healthy weight (56 kg, a BMI of 22) at about 7,600 kJ a day:

• daily target: 7,600 kJ (about 1,810 calories)

• nothing further taken off, and above the 5,000 kJ floor

Split with 20% protein, 30% fat and 50% carbohydrate, all inside the Australian ranges:

This is arithmetic only. Your numbers will differ with your needs, your health and the foods you like, and outcomes vary between individuals.

Check Your Protein

A percentage can hide a low number of grams when your energy target is small, so check protein in grams too. These are the Australian recommended dietary intakes (RDI) of protein for adults:

The worked example gives 89 g, which is above the RDI for all four groups. A smaller target changes that: at 5,000 kJ, 20% protein is 1,000 kJ, or about 59 g, below the RDI for men of any age. Raising protein to the 25% upper level of the range gives 1,250 kJ, or about 74 g, and carbohydrate or fat comes down to make room.

More is not always better. Most Australians already get more than enough protein from food alone, and very high protein diets are not recommended: fad diets promoting 200 to 400 g a day can strain the kidneys and liver (Better Health Channel). A steadier approach is to include some protein in each meal.

Is There a Best Macro Split for Weight Loss?

No single split suits everyone. The Nutrient Reference Values describe quite a wide range of protein, carbohydrate and fat intakes as acceptable for long-term health, and total energy, not the ratio, decides whether weight goes up or down.

Popular splits online often sit outside the Australian ranges. The table checks some common ones, each written as the percentage from carbohydrate, protein and fat:

Low-carbohydrate diets show why the split is not the whole story. In the short term, very low carbohydrate diets can lead to more weight loss than high carbohydrate diets, but in the long term the differences appear to be minimal. Much of the early drop is water, not body fat. Cutting out vegetables, fruit and grains also raises the risk of missing nutrients and of constipation from too little fibre (Better Health Channel).

The same ranges apply to women and men. What differs is energy needs, which vary with sex, age, size and activity, and protein needs, shown in the RDI table above.

Choosing Foods for Each Macro

Hitting your numbers with nutritious food matters as much as the numbers themselves. The Australian Dietary Guidelines recommend eating from the five food groups, drinking plenty of water, and limiting foods and drinks with saturated fat, added salt, added sugars and alcohol.

• Protein: lean meat, poultry and fish; eggs; milk, yoghurt and cheese; nuts and seeds; legumes such as beans, chickpeas and lentils; tofu.

• Carbohydrate: wholegrains such as oats, rice and barley, legumes and fruit. Lower GI carbohydrates take longer to digest and can help you feel full.

• Fat: mostly monounsaturated and polyunsaturated fats, such as olive oil, avocado, nuts, seeds and fish. Replacing foods high in saturated fat with these tends to improve blood cholesterol levels.

Macros, Movement and Muscle

When weight comes off in a short time, the body loses muscle as well as fat, and being active helps prevent that muscle loss (Better Health Channel).

Australia's physical activity guidelines recommend:

• 30 minutes or more of moderate to vigorous physical activity on most days

• muscle-strengthening activities, such as body weight exercises or weights, on 2 or more days a week

• breaking up long periods of sitting

The best way to lose weight in the long term is to change the way you eat and increase your physical activity, not one without the other (Better Health Channel). For more practical ideas, see our guide to everyday habits that support weight loss.

Tracking Your Progress

Macros guide what you eat each day. To see progress over time, look at the trend across several weeks rather than a single weigh-in, and measure your waist as well as your weight. Our guide on how to calculate your weight loss percentage shows how to turn kilograms lost into a share of your starting weight, and our article on how much weight you can realistically lose in a month covers what pace to expect. Outcomes vary between individuals.

Weight is not the only measure. Your GP can also check changes in blood pressure, blood fats and blood sugar, which can improve with only small amounts of weight loss.

Who Should Get Advice First

Talk to a GP or accredited practising dietitian before changing your macros if you:

• are pregnant or breastfeeding, when energy and protein needs go up

• are under 18

• have diabetes, kidney disease or another ongoing health condition

• have a history of disordered eating

When Diet and Activity Are Not Enough

For some adults living with obesity, changes to diet and physical activity may not bring enough weight loss for their health goals. Treatment can include weight loss medication, which is used together with reduced kilojoule intake and increased activity, not instead of them. It has side effects and is not suitable for everyone.

Whether any treatment beyond diet and exercise is appropriate is a decision for a registered healthcare practitioner after an individual assessment, and outcomes vary between individuals. See whether diet and exercise alone are enough and what happens at a weight loss consultation.

If a careful macro split and regular activity have not shifted your weight, Burst Health provides medical weight loss plans online after review by an Australian-registered doctor or nurse practitioner, so you can check whether you are eligible.

Frequently Asked Questions

What macro ratio is best for losing weight?

There is no single best ratio. Weight loss depends mostly on eating less energy than you use, and the Australian reference ranges accept a wide spread: 15 to 25% of energy from protein, 20 to 35% from fat and 45 to 65% from carbohydrate. Choose a split inside those ranges that you can keep up, and results vary between individuals.

How do I figure out my macros for losing weight?

Estimate your daily energy needs at your ideal body weight with a tool such as the Eat for Health calculator. That figure is your target, with nothing further taken off, and it should stay above 5,000 kJ. Split the target by percentage, then divide each share by 17 kJ per gram for protein and carbohydrate, or 37 kJ per gram for fat.

Is 40/30/30 macros good for weight loss?

Not by Australian reference ranges. A 40/30/30 split, with 40% carbohydrate, 30% protein and 30% fat, puts carbohydrate below the 45% lower level and protein above the 25% prudent upper level. It can still sit inside an energy deficit, but a split such as 50/20/30 stays within the ranges. A dietitian can tailor a split to your health.

What should my macros be for 1500 calories a day?

1,500 calories is about 6,300 kJ. With 20% protein, 30% fat and 50% carbohydrate, at 4 calories per gram for protein and carbohydrate and 9 for fat, that works out to about 75 g of protein, 50 g of fat and 188 g of carbohydrate a day. This is arithmetic only. Check that the protein figure meets the RDI for your age and sex, and outcomes vary between individuals.

Why am I not losing weight eating 1500 calories a day?

Energy calculators give estimates, not exact figures, so your real needs may be lower than the number you are using. Judge the trend over several weeks, and measure your waist as well as your weight. If your weight and waist have barely changed after a few months, a doctor or nurse practitioner can review your plan and check for medical causes such as an underactive thyroid.

References

• Eat for Health (NHMRC). Nutrient Reference Values: macronutrient balance.

• Eat for Health (NHMRC). Nutrient Reference Values: protein.

• Eat for Health (NHMRC). Dietary energy, Nutrient Reference Values for Australia and New Zealand.

• Eat for Health (NHMRC). Daily energy requirements calculator.

• Eat for Health (NHMRC). Australian dietary guidelines 1 - 5.

• healthdirect. Kilojoules.

• healthdirect. Protein.

• healthdirect. Carbohydrates.

• Better Health Channel (Victorian Government). Protein.

• Better Health Channel (Victorian Government). Weight loss: common myths.

• Better Health Channel (Victorian Government). Dietary fat.

• Better Health Channel (Victorian Government). Weight loss: a healthy approach.

• Better Health Channel (Victorian Government). Weight management services.

• Markovic TP, et al. The Australian Obesity Management Algorithm (July 2024).

• healthdirect. Obesity.

• Australian Government Department of Health. Physical activity and exercise guidelines for adults (18 to 64 years).

This article is general information only and does not replace individual medical advice. Please speak with a registered Australian healthcare practitioner about your own circumstances.