Nutritional Pearl: Pro-Inflammatory Diets Lead to Weight Gain

Matt is a 37-year-old man who is concerned about his weight and his risk of heart disease. He consumes a fairly standard Western diet, and is curious about what changes he can make to both lower his risk and help him to lose weight.

How do you advise your patient?
(Answer and discussion on next page)

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Answer: A more proinflammatory diet is associated with the risk of overweight or obesity.

Chronic inflammation, which we know contributes to the risk of heart disease and cancers, is more common in those who consume a more Westernized diet, which includes more trans and saturated fats, omega-6 fats (as opposed to omega-3s), sugar, and alcohol. A Mediterranean diet, on the other hand, is a more anti-inflammatory diet, and we've seen that a Mediterranean diet reduces your risk of those inflammation-related illnesses.

James Hébert, a Health Sciences Distinguished Professor at the University of South Carolina, has created a "dietary inflammatory index" to measure the relative pro-inflammatory level of a person's diet. His research analyzes nearly 2000 research articles evaluating 45 food parameters with respect to whether those parameters increase or decrease markers of inflammation in the bloodstream. If the item increases inflammation, it receives a +1 score, if it decreases inflammation, it receives a -1 score, and it receives a zero (0) if the item causes no change in the biomarkers of inflammation. An overall dietary inflammation score is called a DII (Dietary Inflammatory Index), and a higher score would be considered better than a lower score.

The Research

For this research, Dr. Hébert and a team at the University of Navarra in Pamplona, Spain used data gathered from the ongoing study known as the Seguimiento Universidad de Navarra [University of Navarra follow-up], which began in 1999. The study includes over 21,000 men and women who respond to a semiquantitative food frequency questionnaire administered every 2 years. The participants also report on their health, height and weight, and other demographic information like family health history.

Dr. Hébert and his team chose to include for this analysis only those men and women who started the study at a clinically normal weight, were under 65 years of age, were not pregnant or did not become so over the 12 years of follow-up, and whose reported caloric intake were within reasonable parameters—about 7000 men and women. The authors used those participants' food frequency questionnaires to assign each participant a DII score as well as a Mediterranean diet score.

The researchers' focus was on the association between the amount of weight gained over the course of follow-up and the individual's dietary scores, whether DII or Mediterranean diet.

The Results

Those with the poorest DII scores gained more weight, and were more likely to become overweight or obese, than those with the best (highest) DII scores. This held true even after the researchers took into account relevant variables like caloric intake, smoking status, family history, and physical activity.

The authors conclude that a "a more proinflammatory diet... was directly associated with the risk of developing overweight or obesity."

What’s the “Take-Home”?

While this team of researchers took into account caloric intake when performing their analyses, we also know that higher quality calories, which are very often less-inflammatory calories, are often of lower caloric density and of higher nutrient density than those foods that are pro-inflammatory. On a day-to-day level it's far simpler (and just as effective) for your patients to focus on improving their Mediterranean diet score (without worrying about weight loss).

Reference:

Ramallal R, Toledo E, Martinez JA. Inflammatory potential of diet, weight gain, and incidence of overweight/obesity: The SUN cohort; Obesity 2017(25):997-1005.