“Many scientists continue to consider obesity the result of an imbalance between energy intake and expenditure. Citing the law of thermodynamics, scientists and industries articulated the concept of ‘a calorie is a calorie,’ which led to the development of a huge weight loss industry, various diets substituting ‘calories for other calories’ and books promoting ‘eat less and exercise more,’” Artemis Simopoulos of the Center for Genetics, Nutrition and Health in Washington, DC, and James DiNicolantonio of Saint Luke’s Mid America Heart Institute in Kansas, say in the editorial published Oct. 24.
But, they argue, the overly simplistic calorie in and calorie out model is outdated and misleading.
“The sources of calories are important in influencing human metabolism and appetite control,” they say, pointing to the differences between omega-3 and omega-6 fatty acids as evidence.
“Calories from vegetable oils high in linoleic acid, an omega-6 fatty acid, are pro-inflammatory and thrombogenic, whereas calories from eating fish high in omega-3 fatty acids are anti-inflammatory and antithrombotic,” they note.
In addition, high omega-6 fatty acid intake increases white adipose tissue that is stored and prevents its browning, they say. It also leads to an inflammatory state, “which is at the basis of obesity and other chronic diseases,” and is associated with weight gain and increased insulin sensitivity, the editorial notes.
Omega-3 fatty acids, on the other hand, have the opposite effect in many of these cases, they say.
Both are necessary but the balance is off
Even though omega-6 fatty acids are associated with many contributing and influencing factors for obesity and chronic disease, it is essential to human development and therefore necessary in the diet, the researchers acknowledge. But they add, it isn’t necessary at the sky-high levels most Americans currently consume.
They explain that omega-3 and -6 fatty acids are ideal when consumed in a one to one or one to two ratio, with omega-3s being more dominant. However, in recent years this ratio of consumption has shifted in the Western diet to a staggering 16 to 1 omega-6s to -3s, according to the editorial.
The researchers blame this shift on “major changes … in the food supply over the last 100 years,” including the “enormous production of vegetable oils high in omega-6 fatty acids and changed animal feeds from grass to grains” that translate to meat, eggs and dairy products with higher amounts of omega-6s.
They also point to several key studies that support the different impacts of omega-3 and -6 fatty acids on long-term weight gain and other related chronic disease.
Recognizing that the two different fatty acids impact different populations differently, the researchers still conclude that it is “essential to return to a balanced dietary omega-6 to omega-3 ratio based on data from evolutionary studies,” of one to one or one to two.
“The time has come to return the omega-3 fatty acids in the food supply and decrease the omega-6 fatty acids by changing the cooking oils and eating less meat and more fish,” the researchers conclude.
They also place part of the onus for change on manufacturers and suppliers, noting “the composition of the food supply must also change to be consistent with the evolutionary aspects of diet and the genetics in the population” to prevent and treat obesity, diabetes, heart disease and cancer.
Finally, they also call on the government and international public health organizations to “establish nutrition policies based on science” and not on the “same path of focusing exclusively on calories and energy expenditure, which have failed miserably over the past 30 years.”