Perhaps not all calories are created equal. A new paper, co-authored by Saint Luke's Mid America Heart Institute cardiovascular research scientist James J. DiNicolantonio, PharmD, challenges the prevailing belief that all consumed calories - regardless of their sources - are equivalent, and that focusing on calories is a good thing.
Primarily authored by Sean C. Lucan, M.D., M.P.H., M.S., Department of Family and Social Medicine, Albert Einstein College of Medicine, the paper is titled "How calorie-focused thinking about obesity and related diseases may mislead and harm public health. An alternative," and is being published in the journal Public Health Nutrition.
The paper discusses various problems with the idea that "a calorie is a calorie," and with the primarily quantitative focus on food calories. Instead, the authors argue for a greater qualitative focus - paying more attention to the foods from which the consumed calories derive - and on the metabolic changes that result from consuming foods of different types. In particular, Lucan and DiNicolantonio consider how calorie-focused thinking is inherently biased against high-fat foods, many of which may be protective against obesity and related diseases (e.g. nuts, olive oil, oily fish, whole milk), and supportive of starchy and sugary replacements, which are likely detrimental.
The idea that "a calorie is a calorie" implies that any two different foods, which have equivalent amounts of potential energy, will produce identical biological effects with regard to body weight/body fatness when consumed. By this thinking, a calorie's worth of salmon, olive oil, white rice, or vodka would each be equivalent and expected to have the same implications for body weight and body fatness.
But a calorie's worth of salmon, which is largely protein, and a calorie's worth of olive oil, which is purely fat, have very different biological effects than a calorie's worth of white rice, a refined carbohydrate, or a calorie's worth vodka, mostly alcohol - particularly with regard to body weight/body fatness. In fact, studies in humans have shown that calorie-providing proteins, fats, carbohydrates, and alcohol each have substantially different effects on a variety of physiologic pathways and hormones relevant to perceived fullness, subsequent food consumption, weight maintenance, and body composition.
The paper specifically discusses the harmful effects of rapidly absorbable carbohydrates-sugars and refined starches, such as white rice and foods consisting substantively of white flour. These foods cause blood sugar and insulin to rise quickly, which then causes a rapid drop in blood sugar. The result is food cravings, particularly for something sweet.
"The fact is that some calories will squelch a person's appetite and promote energy utilization, while others will promote hunger and energy storage," DiNicolantonio said. "So while some calories send messages to the brain and body that say 'I'm full and ready to move,' other calories are send messages that says '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."
Lucan and DiNicolantonio stress in their paper that public health should work primarily to support the consumption of whole/minimally processed foods - which help protect against obesity-promoting energy imbalance and metabolic dysfunction - and not continue to promote calorie-directed messages that may create and blame victims and possibly exacerbate epidemics of obesity and related diseases.