Calories are king for managing weight whether you're trying to lose fat or gain muscle, according to most nutrition experts.
But the way we calculate calories is inaccurate and misguided, according to Giles Yeo, an obesity expert, researcher at the University of Cambridge, and author of the upcoming book "Why Calories Don't Count."
Current nutrition labels aren't helpful and don't address important factors in metabolism and appetite, Yeo told Insider.
"We eat food, not calories." he said. "The calorie is useful if you're trying to reduce a portion size. But comparing calories and using them across foods doesn't make sense."
Yeo said if you're trying to manage your weight, protein and fiber are more helpful factors than calories alone, and a different way of tracking what you eat could be 10-15% more accurate than current calorie counts.
A calorie is a calorie, but context matters
Yeo isn't questioning whether calories are important for health and weight maintenance. Calories are a basic unit of measurement, and it's a law of physics that losing weight requires burning off more than you eat.
But while calorie counts can tell you how much energy you're ingesting, they won't help you understand how food makes you feel — if you'll be satisfied after eating, or hungry again within 30 minutes.
For example, research suggests nutrients like protein and fiber can make you feel full for longer, and also take more energy to digest, making it easier for you to cut calories if you're trying to lose weight.
Yeo said context matters because it can be unhelpful to tell people to eat less, without explaining how they can do so sustainably.
"The complexity comes in why some people find it more difficult to eat less or move more," Yeo said.
While weight is ultimately determined by calories in versus calories out, the equation for each individual person is also complicated by factors such as lifestyle preferences, time to shop and cook, and access to healthy food and nutrition information.
"Pushing solely personal responsibility without considering the environmental factors isn't helpful," Yeo said.
Make your own calorie counting more accurate with this formula
Yeo said experts and industry leaders could help shift consumers toward healthier habits by providing better information.
"We need nutrition information on food labels, but it's so complex, even for me, who studies nutrition," he said. " I don't think the right information for us to make decisions quickly about what's healthy is there."
For now, he said there's a more accurate way you can calculate calories to account for how protein and fiber are digested differently than sugar.
Currently, labels tally up four calories each for every gram of carbohydrates and every gram of protein in a food. Instead, based on a 2001 study of the energy that's actually available from each nutrient, Yeo suggests:
- 3.8 calories per gram of sugar
- 3.6 calories per gram of complex carbohydrates (including starches)
- 3.2 calories per gram of protein.
Multiply the grams of each macronutrient by the numbers above, and add to get a more accurate calorie total.
While the updated equation might be time-consuming and expensive to roll out on a broad scale, the difference between the current calorie formula and Yeo's suggested update adds up.
The difference could tally around 10-15% of total calories, 200-300 calories a day and and over 1,000 calories a week for an average person.
"It's difficult to do perfectly, but I think we can get better calculations than what we have now," Yeo said. "We know that a few extra calories a day makes all the difference."
