What are macros, and why can two people eat the same number of calories but get different results? Understanding macros can help you lose fat while still enjoying food, staying full, and avoiding the need to cut out rice or skip meals.
What are macros? What does eating by macros mean?
Macro is short for macronutrients—the three types of nutrients your body needs in large amounts every day: carbohydrates (carbs), protein, and fat. These three groups provide all the energy your body needs, from supporting your brain and muscles to keeping your organs functioning normally.
Eating by macros means paying attention to the ratio of these three nutrient groups instead of only counting total calories. You set a gram target for each group and plan your meals around it. This helps you see which nutrients your meal may be missing or overdoing, rather than only looking at the final calorie number for the day.
Each gram of a macro provides a fixed amount of energy:
1g of carbohydrates = 4 calories
1g of protein = 4 calories
1g of fat = 9 calories
Fat provides more than twice as many calories per gram as carbs or protein, so it can push your total calorie intake higher than you realize. A spoonful of oil may not look like much, but it contains a significant number of calories. That is why more people are paying attention not only to calories, but also to macros.
The role of each macronutrient
Carbohydrates: your main energy source, not your enemy
Carbs are often blamed for weight gain, but they are actually the main fuel for your brain and muscles. After you eat them, carbs are broken down into glucose for immediate use, while any excess is stored as glycogen in your liver and muscles.
There are two simple categories. Fast carbs—white rice, noodles, pho, white bread, and sweets—are absorbed quickly, providing immediate energy but often leaving you hungry again sooner. Slow carbs—brown rice, sweet potatoes, oats, and beans—contain more fiber, keep you full longer, and help keep blood sugar more stable.
No type of carb is completely bad. The key is choosing the right type at the right time. When losing weight, choosing more slow carbs can help reduce hunger and cravings. You do not need to eliminate rice completely; cutting it out entirely may only make you give up sooner.
Protein: the nutrient to prioritize when losing weight
If you could focus on only one group, choose protein. Protein helps maintain and repair muscle, keeps you full, and requires more energy to digest than the other two macronutrients. Eating enough protein is one of the easiest ways to lose weight without feeling constantly hungry or losing muscle.
Animal protein—meat, fish, eggs, and dairy—is complete protein containing all essential amino acids and is easy for the body to use. Plant protein—tofu, beans, and nuts—is not always as complete, but it provides more fiber and no cholesterol. Eating both is the most practical approach; there is no need to glorify or eliminate either group.
A practical tip: Vietnamese breakfasts are often seriously low in protein. Sticky rice, plain bread, or pho with very little meat are mostly carbohydrates. Adding an egg or a proper serving of meat can make the meal much more balanced.
Fat
Fat forms part of cell membranes, supports hormone production, and helps the body absorb fat-soluble vitamins such as A, D, E, and K. Cutting fat too aggressively can backfire.
There are three types to know:
Unsaturated fats—olive oil, fatty fish, avocado, and nuts—are the types to prioritize and are good for heart health.
Saturated fats—animal fat, butter, and coconut oil—should be used in moderation. There is no need to fear them, but do not overuse them.
Trans fats—reused frying oil, instant noodles, and margarine—are the type you should genuinely limit.
A small amount of healthy fat in a meal will not make you gain weight. Eating too many total calories is the main cause.
How should you divide your macros?
There is no single ratio that is right for everyone. It depends on your activity level, body composition, and goals. Common nutrition recommendations give a fairly broad range: 45–65% of calories from carbohydrates, 10–35% from protein, and 20–35% from fat.
Within that range, choose the point that fits your goal:
Weight loss: increase protein to around 25–30%, keep fat moderate, and use carbohydrates for the remaining calories. Higher protein helps preserve muscle and keeps you full while eating fewer calories.
Muscle gain: you still need plenty of protein, but do not cut carbs because they provide the fuel needed for hard training and recovery.
Maintenance: a balanced split of around 50% carbs, 20% protein, and 30% fat works well for most people.
How to calculate your macros: a practical example
It may sound complicated, but after doing it once, it becomes familiar. There are two approaches; choose whichever works better for you.
Method 1: divide calories by percentage
Step 1. Calculate your TDEE, the total amount of energy your body uses each day.
Step 2. Adjust it for your goal. To lose weight, subtract approximately 15–20% from your TDEE.
Step 3. Choose the percentage split for the three groups.
Step 4. Convert each percentage into grams.
Here is a specific example. Suppose your target is 1,800 calories per day, split for weight loss as 50% carbs, 25% protein, and 25% fat:
Protein: 25% × 1,800 = 450 calories. Since 1g of protein provides 4 calories, 450 / 4 = 112.5g.
Fat: 25% × 1,800 = 450 calories. Since 1g of fat provides 9 calories, 450 / 9 = 50g.
Carbohydrates: 50% × 1,800 = 900 calories. Since 1g of carbs provides 4 calories, 900 / 4 = 225g.
That means you need approximately 225g of carbohydrates, 112.5g of protein, and 50g of fat per day. Together, they add up to exactly 1,800 calories.
Method 2: calculate protein and fat by body weight, then use carbs for the remainder
This approach is more practical and is commonly used by people who train because it sets protein first:
Protein: approximately 1.6–2.2g per kilogram of body weight when training or losing weight.
Fat: at least approximately 0.6–1g per kilogram of body weight to support hormone function.
Carbohydrates: take your total calorie target, subtract the calories from protein and fat, and divide the remainder by 4.
For example, a 60kg person with a target of 1,800 calories might eat around 108g of protein (432 calories) and 50g of fat (450 calories). The remaining 918 calories come from carbs, which equals approximately 229g. The result is close to Method 1, but the calculation starts from a different direction.
How to eat by macros without feeling pressured
The good news is that you do not need to weigh every gram of rice for the rest of your life. During the first few weeks, tracking macros mainly helps you learn how to recognize portion sizes. After that, many people can estimate their intake fairly accurately.
A few practical tips from Dietfit:
Do not worry too much if one meal is slightly off target.
Prioritize getting enough protein.
Look at the trend across the whole week instead of focusing on a single day.
Do not let one milk tea make you feel that the entire week is a lost cause.
If you do not want to calculate every food by hand, Dietfit can help identify meals from photos and estimate calories, protein, carbs, and fat for many Vietnamese dishes. The goal is not to make you eat perfectly, but to make tracking feel easier.
In summary
Understanding macros does not mean you have to carry a food scale everywhere or weigh every grain of rice from tomorrow onward. Macros are simply a way to see your meals more clearly.
You learn when you are not getting enough protein. You notice when a meal contains too many carbohydrates. You understand that adding an egg or a piece of tofu may be enough to make a meal more balanced.
That is also Dietfit's philosophy: eat smarter, not less. Start with one small change, such as adding protein to breakfast, and observe how your body responds over the next few weeks. If you have a condition such as diabetes or kidney disease, or if you have a specific health goal, consult a doctor or nutrition professional for a personalized ratio, because general formulas may not be appropriate for you.
By Khanh Phan