It’s time to forget about the cabbage soup binges and juice cleanses that promise you'll go down a dress size in three days. The #ELLEfit-proven best way to get slim is by measuring macros. Guaranteed, if you do it right of course, you'll wind up healthier, stronger, and the major plus, leaner than before. 

I was recently convinced by this post-half marathon in Barcelona while I sat beside my running buddy, ELLE art director Miette L. Johnson, drinking a gin tonic the size of my head. She 'does her macros.' She looks hot. 

While she sipped on her cava and explained, here's what I learned: 

The basics: There are three main macronutrients, ie 'macros', carbs, protein, and fat. (I could go into why all these are important to body function but I'll spare you that in the hope that if you are at all health-conscious you have at least a vague idea.) Each macro contains a number of calories, which is what you measure. Each person’s requirements are different though, and based on your basal metabolic rate (BMR).

To get it your BMR right: One of our resident #ELLEFit coaches Jean-Claude Vacassin simplifies for us how they are determined,

‘You can count this up either with fancy tech, or by adding a zero to your weight in pounds (an approximate, but decent start). Your actual calorie requirement is then determined by your starting point and activity level. For many people, for general fitness, 1.2 x basal is a good calorie starting point. That being said, there is no definitive calculation, and it involves some trial and error to see what works for you. Requirements will also change, depending on body composition, season, activity, so it will need tweaking as you progress.’

Additional things that can help your cause: A food scale and a sense of humour.

One gram of protein yields four calories, and one gram of carbs yields four calories, while a gram of fat yields nine. A nutrition label, the scale and a macro counting app will help you figure out what's in the food you plan to eat. 

Eventually, after days or weeks of weighing stuff, you'll be able to eyeball how much 100 grams of protein is and count quickly what that is times four. You'll even boost brainpower by dusting off that side you haven't used since primary school.

If you're thinking, ‘Where does your gin drink fit in to all of this?’ My tipsy/exhausted-ness and this conversation made it clear that this is the best way to get slim while staying healthy. You don’t have to eliminate anything, just balance it all out. And as a Libra, balancing is my jam. Also on a more serious macro note, a gram of alcohol contains seven calories and must be counted like everything else you take in.

On a macro-measuring plan, you can choose to have a full bottle of red wine and some almonds for dinner and still get to your Magic Measure. But you'd probably fall over and feel even worse the next day. I don’t suggest doing that.

‘The assumption is that 80 to 90% of your diet comes for 'clean' nutritious sources,’ says Vacassin. ‘Counting macros allows you flexibility, meaning your diet is inclusive, rather than exclusive. You should still be centered around health and a balanced nutrient intake, rather than a simple way to eat crap within your calorie framework.’

Oh, well, ok then. I get it; I will place the crisps and wine to the side for now.

In Spain, I'm sure I over did my Measure if I knew it then (jamon, queso, and pan tomate in excess) but it was well worth it. Plus, I would have been able to balance it all out again by making sure my next few days were less indulgent. Sweet. 

Eating right and taking care of your body are necessary to get healthy and to help prepare you for what you're training for next, in my case a half triathlon, or maybe just life in general. 

So hop on the #Macro wagon with us, but first, please zero out the scale. 

Our favourite apps to measure macros are My Fitness Pal [Free], My Macros+Diet, Weight, and Calorie Tracker [£2.29], MyNetDiary PRO [£2.99]

Jean-Claude Vacassin is the founding director and a personal trainer at W10 Performance in London. Follow him @jcvacassin