Show Menu


Calories and Macros – The Basics

Calories and macros

​Embarking on a new way of eating and making better food choices can be a daunting prospect. To help those of you new to tracking what you eat or if you just want to be more mindful of your caloric intake, here is a very basic introduction:

First, in a literal sense, a Calorie is always a Calorie since it’s a unit of energy and, as Einstein showed us, energy cannot just disappear.

Second, if you ever need it for a pub quiz(!) a food Calorie (properly known as a kilocalorie, or 1000 calories is the amount of energy required to heat one kilogram of air-free water by 1 °C.

[Another bit of science for you: what we all call “a calorie” is actually 1000 calories, scientifically referred to as a kilocalorie (or “Calorie” with a capital ‘C’) and printed on the side of food packets as “kcal”. But don’t fret or get confused, every popular reference to “calories” in magazines, cookbooks, diet books and the numbers on food packets are all referring to what we all know as “calories”. “Calories”, “calories” and “kcals” are all used interchangeably when it comes to food.]

Macronutrients, or ‘macros’, are nutrients that your body requires in large amounts. There are three primary macronutrients, protein, carbohydrates and fat. Alcohol, technically speaking, is the fourth macro but (before you say it) it is not one our bodies need at all and certainly not in large amounts!

Micronutrients, or ‘micros’, are nutrients referred to as vitamins and minerals consumed in small amounts.

That’s 200 Calories in one mouthful!

Protein’s primary role in the body is to promote growth, development and to help repair cells. Protein has a high thermic effect, meaning it requires a large amount of energy to break it down and digest. Higher protein diets can be a fantastic tool when looking to lose body fat due to it’ effects on muscle mass retention and appetite control.
One gram (1g) of protein equates to four Calories.

Although there is no physiological requirement for carbohydrates in terms of simply remaining alive, carbohydrates are the body’s primary energy source. Carbohydrates play an important role in digestive health, metabolism, athletic performance, mood and even sleep. The more physically active you are (and the more energy you use, the more carbs you may benefit from.
One gram of carbohydrate equates to 4 Calories.

As an essential nutrient, fat plays a crucial role in both optimal health, and athletic performance. Fat is directly involved in the production and regulation of the sex steroid hormones in addition to playing a pivotal part in supporting a healthy immune system.
1 gram of fat equates to 9 Calories.

Alcohol is not required by the body and has a unique metabolic pattern relative to the other macronutrients.
1 gram of alcohol equates to 7 Calories.

To calculate your total calories, simply multiply the number of grams of each macronutrient by its Calorie count per gram. Note – by tracking your macronutrients, you automatically track your Calories too. To learn more about tracking your food intake, read my blog ‘Macro Tracking Made Simple’.

Kevin Garde
Nutritionist and Bodyscan Consultant

How DEXA can help establish your calories and macros

Following a DEXA scan, you’ll have a much better idea of your calorie requirement because DEXA measures your lean body mass. That enables us to use a better formula than the usual online calorie calculators because they assume an average amount of lean/muscle mass for your weight. But if you have low lean/muscle mass, they will drastically overestimate your maintenance calories, telling you that you can lose body fat for a given number of calories when in fact you will probably be either at maintenance or in surplus. That’s why DEXA is a great way of working out your calorie requirement. Watch the DEXA information video below for the detail.

When it comes to macros, the only one you really need to concern yourself with is protein, because it is essential for maintaining and building muscle mass. To reverse-engineer what Kevin says above, once you fix your calories and protein intake, you can simply adjust the other macros (carbs and fat) to meet your calorie number. So if our DEXA calorie calculator concludes you should eat 1700 calories a day and your Bodyscan consultant advises at least 140g of protein (which is 140 x 4 = 560 calories), then that leaves 1140 calories to come from carbs and fats (and indeed more protein) in whatever ratio you like. Perhaps more carbs on an exercise day (for more energy), fewer carbs on a rest day. It’s up to you.

You can discuss calories and macros (and all other aspects of food and training) at your Baseline DEXA scan and you’ll be emailed your calorie target along with your suggested fat-loss and muscle-gain targets.

Book your first scan here. We have two clinics in London – W1 and City.

Philip Chant

Kevin Garde

Rob Webster