Why People Count Macros to Lose Weight

Updated: Mar. 16, 2022

Find out what macros are and why counting macros is thought to help you lose weight without being overly restrictive.

Healthy nutrition concept. Balanced healthy diet food. Meat, fish, vegetables, fruit, beans, dairy products. Top view. Cooking raw ingredients. Organic food. Clear eating. Healthy food idea. Overheadits_al_dente/ShutterstockWhat are macros?

The “If It Fits Your Macros” (IIFYM) diet is a flexible dieting trend that helps people lose weight without being extremely restrictive. If you want to try it (or other popular macro-counting diets, like the ketogenic diet), you need to understand exactly what macros are. Pat Salber, MD, board-certified emergency physician and internist and founder of The Doctor Weighs In says, “Macros as used in IIFYM talk stand for macronutrients or broad classifications of food types. Protein, carbohydrates, and fat are the three primary macronutrients that we consume to supply our bodies with the energy it needs to function properly.”

What can be easily lost in a diet that looks broadly at macros is the great variability within each macronutrient group. All carbohydrates, for example, are not equal. “Table sugar (sucrose) and split peas are both examples of carbohydrates, but the body reacts to each of them differently,” Dr. Salber says. “Sucrose is rapidly broken down into its components, glucose and fructose, which leads to a rapid spike blood glucose and insulin, followed by a relatively rapid decline in blood glucose levels. This may lead to an early return of hunger sensations. Split peas, on the other hand, have a high fiber content. Fiber is a carbohydrate that the body cannot break down so it stays in the gut after ingestion and helps to make the stool bulky and easy to pass. It also is calorie-free,” she adds.

Some people will find it tiresome to do all the counting that’s necessary with a macro diet. Even seemingly simple foods such as walnuts are made up of more than one macronutrient. “The calories from walnuts come primarily from fat (including Omega 3 fats), but also from protein and carbohydrate,” Dr. Salber says. “Think of the complexity of trying to calculate macros in prepared foods, junk foods, or the typical casserole or stew that you prepare at home.”

What is the IIFYM lifestyle all about?

The IIFYM lifestyle is about making sure that, whatever your food choices each day, your macro counts fall into a specific range. That range is personalized and dependent on things such as your gender, age, daily activity level, and weight-loss goals. You start by using the IIFYM calculator (it’s free but you need to give your email address and agree to their marketing to get the results) to figure out exactly how many carbs, fats, proteins, and total calories you should be eating on a daily basis. That’s the easy part.

How do you actually count macros?

Counting daily macros is a numbers game. “After you know your daily calorie needs, you determine the level of calories you can consume of each macro,” Dr. Salber says.

For instance, I’m a 30-year-old female and looking to lose some weight, so the calculator shares that I should aim for 1,557 calories per day, focusing on eating 115 grams of protein, 58 grams of fat, 144 carbohydrates and 21 grams of fiber per day. Using a nutrition app like Lose It or MyFitnessPal can help you keep track.

How do macros help with weight management?

If IIFYM doesn’t sound all that new to you, you’re right. “There is nothing new about a diet that allows you the flexibility of selecting different foods from different categories as long as you stay in a calorie deficit,” says Dr. Salber. “Weight Watchers has been doing this for years… But there is more to a healthy diet… you need to consider other physiologic effects of foods, such as on the brain, hormones, and microbiome, as well as other nutrients, such as vitamins, minerals, and healthy fats.”

So why are so many people touting success counting macros? Dr. Salber believes the focus on numbers encourages followers to eat at a calorie deficit. “People on IIFYM who are able to significantly decrease their calories below their daily needs should be able to lose weight.” But at what cost to their overall health? This depends on the quality of their food choices. The IIFYM site encourages followers to “eat the foods you love.” For some that might include a lot of processed foods with a long list of chemical ingredients and bad fats that have little in the way of vitamins and minerals. And over the long haul, that’s going to take a toll on their health.

“Substituting a balanced diet of fresh, whole foods for processed foods and junk foods may make you happy in the short term,” says Dr. Salber, “but is unlikely to lead to a healthy body in the long run.”

Why is the IIFYM diet gaining popularity?

The IIFYM site may make the diet sound almost too good to be true. “The IIFYM diet plan allows you to eat the same food you already eat while triggering rapid fat loss. No more restrictions. No more suffering. No more dieting!” Those words are pretty convincing and the concept has taken off like a wildfire. Dr. Salber says, “Who wouldn’t want to believe this claim?”

What are the most important things to take note of when counting macros?

“When it comes to classifying foods by macros, realize that some foods have impacts on weight gain or loss that go beyond how many calories they have, Dr. Salber says. She sites a 2017 study in the journal Diabetes, Obesity, and Metabolism that demonstrates that the ingestion of walnuts is associated with brain activity that may reduce certain food cravings.  (The study was supported in part by the California Walnut Commission.)

“Other foods, such as fiber-rich foods are beneficial to our gut microbiome, the collections of bacteria that not only inhabit our intestines, but also help regulate factors related to weight gain or loss,” she points out.

And of course, food also contains micro nutrients, such as vitamins and minerals. “We know that vitamins and minerals may have different effects on physiology depending on how they are ingested. This is why most doctors and nutritionists recommend getting your vitamins and minerals via the foods you eat, not as supplements,” Dr. Salber says. (However, if you do take them,  here are the supplements that medical professionals trust the most.)

Is there any research that proves that counting macros is effective?

While there has been research over the years about various diet plans, there hasn’t been anything to prove (or disprove), how effective counting macros can be.

“Although the Internet is filled with testimonials about the effectiveness of this diet, I didn’t find any scientific papers that actually demonstrated that it works. Weight Watchers, on the other hand, has been shown to help people lose weight compared to standard dieting approaches. And the Mediterranean and DASH diets have been shown to have significant impacts on cardiovascular health,” Dr. Salber says.

“The bottom line is there are no magic bullets when it comes to weight loss. Whether you count macros, count points, or count calories, [the success of these diets] boils down to consuming fewer calories than you burn each day,” she says. But for long-range health, the key is being mindful of the non-calorie impacts (either beneficial or deleterious) different foods have on things like our gut microbiome, neurotransmitter signaling, energy, sleep, digestion, and feelings of satiety.

The quality of food choices always matters, and that’s a fact that so many trendy diets like to gloss over. “Declaring it is not dieting doesn’t make it true,” says Dr. Salber.