Protein gives you 4 calories per gram. Carbohydrate gives you 4. Fat gives you 9. Alcohol gives you 7. Those four numbers explain most of what confuses people about food labels, and they are worth committing to memory.
Why fat carries so much more
Fat packs more than twice the energy of the other two per gram, and that is chemistry rather than nutrition politics. It is a denser store of energy, which is precisely why bodies use it for storage.
The practical consequence shows up on the plate. A tablespoon of olive oil is around 120 calories and disappears into a salad without filling anyone up. A large plate of vegetables costs less than that and takes ten minutes to eat.
That does not make fat the enemy. You need it for hormone production and to absorb vitamins A, D, E and K, and meals with some fat in them are more satisfying. But it is the macronutrient where careless measuring costs you the most, because the error per spoonful is large.
Protein: 4 per gram, and cheaper than it looks
Protein technically gives you 4 calories per gram, but you keep less of that than you do from carbs or fat. Digesting protein costs energy, more than the other two, so the net figure lands somewhat lower.
That is a small bonus on top of the two things protein actually does well: it keeps you full, and it protects muscle while you are eating less. Animal sources give you the full set of essential amino acids. Most plant sources are short on one or more, so a varied intake matters more if you eat that way.
Carbohydrate: 4 per gram, wildly variable in practice
The 4 is fixed. What differs is what comes attached.
A hundred grams of white sugar and a hundred grams of oats carry similar energy and behave nothing alike, because fibre changes how fast the energy arrives and how full you feel. Fruit, vegetables, whole grains and legumes bring fibre and micronutrients along with the calories. Sweets bring the calories.
Fibre complicates the arithmetic too, since some of it passes through undigested. That is the basis of the net carb idea, which our guide to net carbs covers in full.
Alcohol: 7 per gram, and it jumps the queue
Alcohol is closer to fat than to sugar on the energy scale, which surprises people who think of a spirit as a lighter option than a dessert.
Worse, your body treats it as a priority. Alcohol cannot be stored, so metabolising it comes first and everything else waits, including fat burning. So a night out is not just the calories in the glass. It is the calories in the glass, plus the ones you eat alongside them, processed by a body that has paused its other work.
It also brings no protein, no fibre and effectively no micronutrients. If your intake is tight, this is the easiest place to find room.
What this means for your macro split
Once you know your maintenance calories, the split decides what those calories feel like.
More protein for fullness and muscle. Enough fat for hormones and palatability, without letting it eat the budget. Carbohydrate to fuel whatever training you do. Rough proportions beat precise ones here, and the calculator on the homepage will do the sums for three common splits against your own number.
Where people trip up
Measuring oil by eye. A generous glug is three tablespoons, and that is 350 calories nobody logged.
Forgetting drinks entirely. Beer, wine and juice go down fast and do almost nothing for satiety.
Chasing macro precision while ignoring the total. If your calories are wrong, a perfect 40/30/30 split will not save you. Get the total roughly right first, then tune the ratio. Our guide to tracking accurately has the rest of the traps.