Environmental Nutrition

Many nutrition professionals, including dietitians, have a good idea what macronutrient breakdown most people should be aiming for. This target as a percentage of total daily calories would be 45% to 60% carbohydrates, 15% to 25% protein and 20% to 35% fat. But in recent years as a raft of specialized diets like keto and carb cycling have gained momentum, more people have been adjusting these ratios to what they believe better aligns with their desired goals like weight loss. Which begs the question: Are macros worth messing around with or should we be sticking with established guidelines?

So, what are macronutrients exactly? "They are carbohydrates, proteins and fats that the body requires in large amounts for growth and development," says Lisa R. Young, Ph.D., R.D.N., author of "Finally Full, Finally Slim." In fact, "macro" is a Greek word that means "large". Each gram of carbohydrate and protein contains roughly four energy calories, while a gram of fat provides nine calories. What is not a macronutrient? "Vitamins and minerals are micronutrients since they are required in smaller amounts," Young explains.

A macro-centric diet shifts the focus from total calories to the ratios of carbs, proteins and fats consumed, and, in turn, places more importance on where calories are hailing from. This can vary greatly depending on what diet plan an individual is latching onto. For instance, those adhering to a keto diet may glean 60% to 80% of their calories from fat and as little as 5% to 10% from carbohydrates, which is a big contrast from standard nutrition advice.

The protein-forward Paleo diet can bring the percentage of daily calories from protein up to 30% or more. An endurance athlete may amp up their carb intake to the point where it reaches as much as 70% of overall calories. And with the diet known as carb-cycling, people will adjust their carb intake throughout a week or month to include low (5% to 10%), medium (40%) and high (60%) carb days.

What's up with all this playing around with macro numbers? It all comes down to adjusting macros for a targeted purpose, be it weight loss or improved athletic performance. An individual looking to put on extra lean body mass may choose a bigger piece of chicken to bump up what percentage of calories they get from protein.

Those on fat-forward keto believe focusing on dietary fats instead of carbs makes the body more efficient at burning fat, reduces appetite and does a better job at trimming the waistline. "A lot of this comes down to people following current dieting trends," Young says. While there is plenty of anecdotal evidence floating around social media regarding the success of certain macro ratios, for the most part we lack long-term studies to gauge what impact big swings in macronutrients can have on our health and weight loss efforts.

"It's important to remember that drastic changes to macronutrient intake are hard for most people to sustain long-term," notes Young. She adds that the established macro guidelines are what most people go back to because they are easier to follow and provide more flexibility. The concern when people regularly alter their macro intakes is that it can lead to frequent weight fluctuations and recent research shows that the stress on the body from this can raise the risk for early death. And in the battle of the bulge, what you eat is just as important as where your macros are hailing from. A recent study in the journal JAMA found that people lost about the same amount of weight over a one-year-period on a low-fat, higher-carb diet as on a diet with a macro ratio skewed more towards fat than carbs as long as the diets were focused on whole foods instead of processed ones.

The tricky thing about macronutrients is that the amount of each you should be eating can vary drastically from person to person. For instance, a sedentary individual will likely require a macro ratio that isn't as strongly skewed towards carbs as does a full-time endurance athlete. Some can thrive on obtaining a higher percentage of calories from protein while others will always feel beaten down by this dieting strategy. For this reason, it is a good idea to meet with a registered dietitian to suss out what macro adjustments work best for you and will be sustainable over the long-haul. "And it's always a good idea to ease into macro shifts slowly," adds Young. Expect a bit of trial and error as you're tweaking macros. As of now, there is no right answer on what your macros should look like.

(Environmental Nutrition is the award-winning independent newsletter written by nutrition experts dedicated to providing readers up-to-date, accurate information about health and nutrition in clear, concise English. For more information, visit www.environmentalnutrition.com.)