How to count calories and macros: a simple beginner's guide

Step 1: work out a daily calorie target

Your daily energy use has two parts: what your body burns at rest, and what you add by moving about. Most calculators, including the one in Fuel Log, use the Mifflin-St Jeor equation for the resting part:

• Men: 10 × weight in kg + 6.25 × height in cm − 5 × age + 5
• Women: 10 × weight in kg + 6.25 × height in cm − 5 × age − 161

Then multiply by an activity factor to get your total daily energy expenditure (often called TDEE):

Finally, adjust for your goal. A kilogram of body fat holds roughly 7,700 kcal, so eating about 550 kcal a day below your TDEE works out at around 0.5 kg a week. Slow and steady is easier to keep up than a crash diet.

Step 2: split it into macros

Macros are the three nutrients that make up your calories. A sensible, flexible split starts with protein, then fat, and fills the rest with carbohydrate:

• Protein (4 kcal per gram): around 1.6 to 1.8 g per kg of body weight is a common target for active adults, and helps you feel full.
• Fat (9 kcal per gram): roughly a quarter to a third of your calories.
• Carbohydrate (4 kcal per gram): whatever's left. It's your main fuel for exercise.

Fibre counts within carbohydrate, and alcohol has 7 kcal per gram but isn't a macro you need to hit.

A worked example

This is exactly the calculation Fuel Log runs when you fill in your profile. It also won't set a target below 1,200 kcal for women or 1,500 kcal for men, because going lower is hard to do safely without professional support.

Step 3: log food accurately

1. Weigh things at first. Kitchen scales are the single biggest improvement. After a couple of weeks you'll be much better at judging portions by eye.
2. Log as you go, not from memory at bedtime. Snacks and drinks are the easiest things to forget.
3. Count cooking oil, sauces and drinks. A tablespoon of olive oil is about 120 kcal; a large latte can be 200.
4. Use the packet for packaged food, and a database entry for fresh and home-cooked food. Weigh raw or cooked consistently, since rice and pasta roughly double in weight when cooked.
5. Save meals you repeat. If your breakfast is the same most days, one tap beats searching every morning.

Counting calories in Fuel Log

Fuel Log sets your targets from your profile and keeps the diary on your device.

• Set up your profile with sex, age, height, weight, activity level and goal. Fuel Log works out your calories and macros with the formula above, and you can change them with Edit targets in Settings.
• Add food to Breakfast, Lunch, Dinner or Snacks. Search the built-in database of over 600 foods with common portions, or scan a barcode with your camera where your browser supports it (or type the number). Barcode lookups use the public Open Food Facts database and send only the barcode number.
• Quick add a calorie and macro total when you don't know the food, copy yesterday's meal, or save a meal to log it again in one tap.
• Log water and exercise. Tap glasses towards your water goal (8 by default), and pick from activities such as brisk walking, cycling or yoga.
• Weigh in and follow the smoothed weight trend, which irons out day-to-day ups and downs.

All of that is free, with no ads and no sign-up. Fuel Log Pro ($3.99 once) adds recipes, a fasting timer, weekly nutrition reports and a meal photo diary. You can back up your diary to a file from Settings.

Reading your weight sensibly

Daily weight can swing by a kilogram or more from water, salt and what's still in your gut, so one reading tells you very little. Weigh at the same time each morning, look at the trend over two to three weeks, and only then adjust your target, by 100 to 200 kcal at a time.

Common mistakes

• Guessing portions. "A bowl of cereal" can be 30 g or 90 g.
• Forgetting drinks, oils and bites while cooking. They add up quickly.
• Cutting too hard. Very low targets make you hungry and tired, and are hard to keep up.
• Reacting to a single weigh-in. Follow the trend, not the day.
• Eating back every exercise calorie. Activity estimates are rough; many people eat back only part of them.