Acting as a gatekeeper of calories is often considered an obvious part of managing our weight, and controlling the contents of our meals. Many of us have assumed that as long as you eat about 2,000 calories per day, it doesn’t always matter what you eat.

But researchers are now discovering that obesity isn’t always caused by a large intake of calories; rather, it has a lot to do with “metabolically disruptive” foods, according to a new study review published in Public Health Nutrition. The review, led by cardiovascular research scientist James DiNicolantonio of St. Luke’s Hospital, argues that keeping count of calories is useless when you’re not paying attention to the metabolic effects of certain foods, like simple carbohydrates and sugars.

“Every country around the world is having a problem with obesity, and so far nothing has worked,” DiNicolantonio told the Huffington Post. “But it’s important to note that we’re not dying of obesity, we’re dying of chronic metabolic disease.”

Not All Calories Are Created Equal

DiNicolantonio says that the prevailing ideas regarding diets is that "a calorie is a calorie," and that it doesn’t matter what you eat as long as you don’t eat too much of it. But this isn’t always true, he argues, calories are not all equivalent. Calories from sugar, high-fructose corn syrup, potatoes, white rice, cereal, and anything made from white flour affect the body differently than calories from vegetables or whole grains. They spike blood sugar and cause insulin levels to rise, then drop blood sugar again and trigger more carb cravings in the person. This ultimately creates a “loop for overconsumption,” DiNicolantonio said.

“The fact is that some calories will squelch a person’s appetite and promote energy utilization, while others will promote hunger and energy storage,” he said. “So while some calories send messages to the brain and body that say 'I’m full and ready to move,’ other calories send messages that say ‘I’m still hungry and just want to lie down on the couch.’ Not all calories are the same, and in order to promote healthy weight and better health, we need to take special note of the calories we are choosing to consume.”

Metabolic Health

The important thing, then, is to focus on your metabolic health and the metabolic healthiness of the foods you eat instead of the amount of calories, DiNicolatonio said. Or, in other words, to switch your “calorie-focused thinking” to “more-nuanced thinking.” If this were the case, you’d be consuming fewer fruit juices, breads, pastas, cereals, and even low-fat dairy items like sugary yogurts (which might seem calorie-sensible), while embracing some calorie-rich but metabolically healthy foods like nuts and nut butters, avocados, olives, and whole-dairy products.

Metabolic syndrome, or chronic metabolic disease, refers to a group of risk factors that can cause a higher risk for heart disease, diabetes, stroke, and other health issues, according to the National Institutes of Health. The risk factors include a large waistline or abdominal obesity, a high triglyceride level (a type of fat in the blood), a low HDL cholesterol level (the “good” cholesterol), high blood pressure, and high fasting blood sugar.

Interestingly, there are some obese people who are considered fit and metabolically healthy, and who don’t have any of these risk factors. In a study published in the European Heart Journal in 2012, researchers found that obese and overweight people who were deemed metabolically healthy were no more likely to develop chronic disorders like diabetes and high cholesterol than skinny but unfit people. “It is well known that obesity is linked to a large number of chronic disease such as cardiovascular problems and cancer,” said Dr. Francisco Ortega, an author of the 2012 study, in a press release. “However, there appears to be a subset of obese people who seem to be protected from obesity-related metabolic complications. They may have greater cardio-respiratory fitness than other obese individuals, but, until now, it was not known the extent to which these metabolically healthy but obese people are at lower risk of diseases or premature death.” It’s possible that these obese-yet-fit people focus more on calorie-rich, healthier foods.

“Acknowledging that not all calorie sources have equivalent effects in the body is crucial, and the ‘calorie is a calorie’ theory actually prevents this,” Tulane University nutrition professor Lydia Bazzno told HuffPost. “These macro-nutrients, carbohydrates, fats, and protein go down different metabolic pathways in our bodies and produce different feelings, trigger different hormones and cellular messengers, producing different outcomes in terms of weight and disease risk.”

So, before you fill your shopping cart with low-fat, empty-calorie items, think smart and perhaps a bit “more nuanced” about your metabolism.

Source: Lucan S, DiNicolantonio J. How calorie-focused thinking about obesity and related diseases may mislead and harm public health. An alternative. Public Health Nutrition. 2014.