We’ve all heard “calories in calories out” or “you need to burn 3,500 calories deficit to lose a pound of fat.” But science is proving that counting calories is not a reliable strategy for losing weight.
WNYC’s radio program Only Human recently published a great episode called “Don’t count on the calorie,” where they discussed, among other things, how changing the composition of foods affects the amount of calories our bodies can obtain from those foods.
For instance, a snack pack of almonds might read 100 calories on the label but it’s more likely that you’d only be able to get 70 calories out of that serving, because of the work necessary to break them down. On the flip side, cooking foods, especially starchy foods, increases their caloric availability.
The radio hosts even ask the question about whether ultra-processed foods such as cereals, cookies, bread, chips and the like actually provide more calories than the packaging suggests. I wouldn’t be surprised if that’s the case. Processed foods, structurally changed by mechanical and chemical processes don’t require as much effort from the body to extract their calories. I like to call them easy calories.
And then things really got interesting when discussing the impact of the microbiome on the body’s ability to burn calories. It turns out that an unhealthy gut makes it harder to burn calories effectively.
They cite one example of a woman eating the exact same amount of calories as she did prior to a hospital acquired infection that she survived via fecal transplant from her obese daughter. She gained forty pounds.
A recent University of Iowa study in mice showed that certain drugs are able to alter the gut bacteria in a way that decreases the body’s resting metabolic rate, the amount of calories burned during rest or sleep. The study specifically focused on the effects of the antipsychotic drug risperidone, however other drugs alter the microbiome, like the often overused antibiotics.
The researchers reported about a 16 percent change in resting metabolic rate, which “would be 29 pounds of fat gained every year for an average human,” according to John Kirby, University of Iowa professor of microbiology. “That is the equivalent of eating one additional cheeseburger every single day.”
And, the overall composition of your diet, not just individual foods can change your calorie burning potential. When it comes to weight loss, low-carbohydrate diets outperform the low-fat diet people sometimes follow in order to restrict more calories, since fats are more calorie dense than carbs.
However, another study found that a low carbohydrate diet is more effective than conventional approaches at burning calories and keeping energy expenditure higher even after weight loss. Several other studies support the efficiency of a low-carb or low-glycemic diet when it comes to weight loss.
According to David Ludwig, Professor of Pediatrics at Harvard Medical School, “total calories burned plummeted by 300 calories on the low-fat diet compared to the low-carbohydrate diet, which would equal the number of calories typically burned in an hour of moderate-intensity physical activity.”