One of the easiest ways to start a brawl between nutritionists and trainers and athletes is to make a statement about how many carbohydrates a person ought to consume in a day. Because, just as fat once had the bad reputation in the three’s-a-crowd table of macronutrients, it has since been heralded as the answer to all our health and weight woes. And now instead of fat shaming people who eat butter, we stare in shock at someone holding a sandwich. Really? Who even eats bread anymore?

Thankfully, we have science to give us a clear statement on how we should eat for optimal fitness. The problem is that most of us are not sitting in a laboratory eating calorie-rationed meals and walking miles on a treadmill. And then there’s this little thing called bio-individuality. So science cannot really be clear at all.

As much as we’d like to hide behind our genetic makeup and assume we are victims of the unseen code that makes us inefficient calorie burners, this logic does not appear to be valid. Nor does the idea that calories in < calories out = weight loss. Numerous studies show that factors ranging from gut bacteria to hormone imbalance can have a significant impact on how your particular body metabolizes. So how the hell do we know what we should eat?

First, we need to know what macronutrients are: carbohydrates, fats and protein. Carbs and protein are 4 calories to the gram and fats are 9 calories to the gram. While it is true that fat does not make you fat, excess calorie intake does – and that’s easy to do with butter. Your body can turn all of those nutrients into glucose for energy. Carbohydrates are the most simple to convert, then protein, then fat.

How many nutrients you should eat in a day depends on several unique factors: who you are, what you are doing, and what you want to achieve. And always, always there are exceptions. Look at those amazing vegan athletes out there defying all weight-training advice and pumping iron on falafel, for example.

Who you are: This is the most unique part of understanding your nutrition. A diabetic person cannot take the same nutritional path as a person without diabetes. A person with autoimmune disease cannot (or most certainly should not) eat grains as their source of carbohydrates. History must also be taken into account. Is there a history of previous drastic weight loss? This can permanently lower metabolism. Is there a history of drug or antibiotic use that has impacted the gut micro biome? Knowing these things and understanding how they impact your nutritional needs helps you assess the next key element.

What you are doing: This is always a moment for blatant honesty and can be uncomfortable. I recently weighed out what I thought was a tablespoon of peanut butter. It turns out, I’ve been eating more like a quarter cup for YEARS and wondering why my jeans keep getting tighter. There is a measure of accountability in this. My clients absolutely loathe this part, and I usually get an explosion of hateful text messages when I ask them to track their food for a week. How many carbohydrates are they really getting? Where are their best protein sources? Are they undereating in the morning then gorging at night?

(By the way, I like using MyFitnessPal or other apps to track calories and assess macronutrient intake for about a week. Usually that’s enough to get an idea of how much peanut butter and cocktails are hurdles to our goals.)

What you want to achieve: If you want to create a change, let’s say drop a few pounds for a race or increase lean muscle mass, then you’ll want to change your macronutrient ratios. Look at where they are and make small shifts based on your goals. Want to lose weight? Reduce your fat intake slightly and increase your protein. Want to gain muscle? Increase your protein intake drastically and eat enough carbs to keep your muscle from breaking down.

The simple reality is that we need nutrient-dense foods to stay healthy, and an excess or deficiency in any of the macronutrients will cause imbalance. Make your body the science lab and find out what works best for you. Chances are, the solution is as unique as you. //