Ask a Dietitian: How Do You Estimate the Macros in Your Food?

Hi Charlotte, how do I estimate the macros in things like homemade vegetable soup and salads?

For people who have heard of macros but aren’t exactly sure what they are, let me give you a quick rundown. Macros are short for macronutrients. In other words they’re nutrients we need in our diets in large amounts, namely: carbohydrates, fats, protein and fiber. When someone says they track their macros, they mean they are calculating how many calories of each macronutrient they are consuming across a meal, day or week.

When you read the news it seems like the field of nutrition changes its mind every day so it’s odd to think the way to estimate macros hasn’t changed in over 100 years. You can estimate your macros using something called the Atwater system, named after the guy who came up with it. The Atwater system gives you a rough idea of how many calories a gram of each macronutrient provides.

Fat = 9 calories per gram

Carbohydrate = 4 calories per gram

Protein = 4 calories per gram

Alcohol = 7 calories per gram (yes, I know it’s a lot!)

You’ll notice that fiber doesn’t have a value because it gets lumped in with carbohydrates. If you want to track fiber I’d recommend using 2 calories per gram instead, which will be more accurate.

You could get out a pen and paper and calculate this for every meal. You could also plug these numbers into a nutrition app or website which will do it for you. I think the latter is much easier and whatever calculator you find will use the same Atwater factors you were going to use anyway.

Now, it’s important to say that I don’t think estimating macros is that helpful; they don’t tell you much and they don’t really relate to health either. The only time I think tracking macros is useful is when you’re combining that with a gym goal or looking to decrease feelings of hunger during weight loss, and even then I would only focus on tracking protein, and not worry about carbs or fats.

On the face of it estimating macros is simple, but often not that helpful, so if you are estimating, make sure it’s helping towards a goal you’ve set yourself. 

TL;DR

Most people don’t need to estimate their macros, but if you do, don’t be afraid to use apps to give you a helping hand.

Written by: Dan Clarke, RNutr
Reviewed by: Charlotte Marie Werner, MS, RD, CDN

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