As if counting calories isn’t stressful enough, there’s a diet trend that’s gaining popularity among CrossFitters, bodybuilders, models and social media enthusiasts seeking a leaner physique.

If It Fits Your Macros (IIFYM), also called Flexible Dieting, requires you to calculate and monitor not only your daily calorie goals to lose weight, but also the calories you’re getting from each of the macronutrients (macros): carbohydrates, protein and fat. This requires using a smartphone app or spreadsheet every day to stay on track.

How do you calculate your ideal macros? Typically, you’ll start by aiming to get 1 gram of protein for every pound you weigh. Then based on whether you are naturally slim or tend to store more fat, you’ll adjust your calories from fat to be 25 percent to 35 percent of your daily energy. Carbs will make up the rest of your calories, meaning leaner people will eat more carbs and heavier people fewer carbs.

What IIFYM isn’t

Fans suggest IIFYM gives you the wiggle room you need to enjoy some of your favorite foods — as long as they fit into your macro and calorie goals.

Media coverage of IIFYM lauds it as a diet that lets you eat doughnuts, French fries and fettuccine alfredo while still losing fat and gaining muscle. You don’t have to be a nutrition expert to know this isn’t a recipe for success. If you’re counting calories as IIFYM demands, it would be impossible for you to eat these foods frequently and still meet your goals.

Do macros matter?

A calorie isn’t just a calorie. Calorie counting encourages people to see 300 calories of chocolate cake as equivalent to 300 calories of salmon when clearly, they have very different effects on your weight loss results and health.

Let’s start with protein. The Recommended Dietary Allowance for protein is 0.4 grams for each pound of body weight a day. IIFYM suggests you get more than double this amount, making it a high-protein diet.

Protein is prioritized in IIFYM and other diets for good reason. Protein speeds up your metabolism and keeps you feeling full longer.

In athletes trying to lose weight, higher protein intakes can help maintain muscle mass during gradual weight loss over a couple of weeks. In non-athlete overweight adults, however, higher protein intake (0.8 grams per pound vs. 0.4 grams per pound) didn’t prevent muscle loss during a weight-loss diet where they reduced calories by 25 percent for three months.

The differences in these results suggests eating more protein may be better for athletes than for ordinary people.

What about carbs? The Institute of Medicine recommends you get 45 percent to 65 percent of your calories from carbohydrates. With IIFYM, your carb intake could be lower than this. The average American gets 50 percent of their calories from carbs, with too much of it (250 to 350 calories a day) coming from added sugars. So will lowering your carb intake help you lose weight and keep it off?

Probably not. When quality weight loss studies are analyzed together, there is no difference in weight loss up to one year between lower-carb, higher-fat diets (4 percent to 45 percent of calories from carbs, 30 percent to 75 percent of calories from fat) vs. higher-carb, lower-fat diets (50 percent to 65 percent carbs, and 20 percent to 25 percent fat) when calories are the same.

Higher-carbohydrate or higher-protein diets also seem to lead to the same amount of weight loss as long as you keep calories equal.

The bottom line

IIFYM has its merits. It allows you the flexibility to enjoy your favorite foods and still see results. The main issues with IIFYM are it’s time-consuming, complicated and not evidence-based, and ignores food quality.

For the average person, planning and tracking macronutrient intake every day can get tedious and may foster an unhealthy obsession with food.

Tracking what you eat can help you lose weight, but there isn’t any evidence that tracking macros can offer you a greater weight-loss advantage than other calorie-counting diet plans.

With any eating plan, food quality matters. The ideal diet isn’t just about macros; it’s about choosing healthy, whole foods over heavily processed foods. There are healthy and less healthy types of carbs and fats. Focus on getting most of your carbs from fiber-rich vegetables, beans, fruit and whole grains over added sugars or white bread. And when you choose where to get your fat from, nuts and oily fish are better choices than fried foods.

There isn’t a single diet that works for everyone, so seeing a dietitian for individualized advice is a great idea. My nutrition philosophy is similar to flexible dieting in that you eat as healthy as possible most of the time and enjoy less healthy treats once in a while. The difference? You don’t have to use spreadsheets or diet apps. It’s about finding the balance that works for you.