Field Notes

‘Everything in Moderation’ Diet Advice May Lead to Poor Health

Diet diversity, as defined by less similarity among the foods people eat, may be linked to lower diet quality and worse metabolic health, according to researchers at The University of Texas Health Science Center at Houston (UTHealth) and the Friedman School of Nutrition Science and Policy at Tufts University.

“‘Eat everything in moderation’ has been a long-standing dietary recommendation, but without much empirical supporting evidence in populations. We wanted to characterize new metrics of diet diversity and evaluate their association with metabolic health,” says Marcia C. de Oliveira Otto, PhD, first author and an assistant professor in the department of epidemiology, human genetics, and environmental sciences at The UTHealth School of Public Health.

Using data from 6,814 participants in the Multi-Ethnic Study of Atherosclerosis, a study of whites, blacks, Hispanics, and Chinese Americans in the United States, the authors evaluated diet diversity through different measures. These included the total count (number of different foods eaten in a week), evenness (the distribution of calories across different foods consumed), and dissimilarity (the differences in food attributes relevant to metabolic health, such as fiber, sodium, or trans fat content).

The study examined how diet diversity was associated with change in waist circumference five years after the beginning of the study and with onset of type 2 diabetes 10 years later, waist circumference being an important indicator of central fat and metabolic health.

When evaluating both food count and evenness, no associations were seen with increase in waist circumference or incidence of diabetes. In other words, more diversity in the diet wasn’t linked to better outcomes. Participants who had the greatest food dissimilarity actually experienced more central weight gain, with a 120% greater increase in waist circumference compared with participants with the lowest food dissimilarity.

To compare with the results seen for diet diversity, the researchers also examined how diet quality relates to metabolic health. Diet quality was measured using established scores such as the Dietary Approaches to Stop Hypertension score and the Alternative Healthy Eating Index score. At five years, diet quality wasn’t associated with change in waist circumference. At 10 years, higher diet quality was associated with about a 25% lower risk of developing type 2 diabetes.

“An unexpected finding was that participants with greater diversity in their diets, as measured by dissimilarity, actually had worse diet quality. They were eating fewer healthful foods, such as fruits and vegetables, and more unhealthful foods, such as processed meats, desserts, and soda,” Otto says. “This may help explain the relationship between greater food dissimilarity and increased waist circumference.”

Dietary diversity as measured by food count and evenness also was associated with higher intakes of both healthful and unhealthful foods.

“Americans with the most healthful diets actually eat a relatively small range of healthy foods,” says Dariush Mozaffarian, MD, PhD, senior author and dean of the Friedman School of Nutrition Science and Policy at Tufts University in Boston. “These results suggest that, in modern diets, eating ‘everything in moderation’ is actually worse than eating a smaller number of healthful foods.”

— Source: University of Texas Health Science Center at Houston


Adolescent Bariatric Surgery Reverses
Type 2 Diabetes in 95% of Teens

The results of a study published in The New England Journal of Medicine show that three years after undergoing bariatric surgery, adolescents experienced major improvements in their weight, metabolic health, and quality of life.

Teen-LABS (Longitudinal Assessment of Bariatric Surgery), a multicenter clinical study examining the safety and health effects of surgical weight loss procedures, is the largest and most comprehensive analysis of bariatric outcomes to date in adolescents. The study enrolled 242 adolescents, aged 13 to 19, all of whom were severely obese with an average weight of 325 lbs before surgery. The participants had an average BMI of 53. Three years after surgery, average weight had decreased by more than 90 lbs, or 27%. Most participants also had reversal of a number of important obesity-related health problems. Reversal of type 2 diabetes was seen in 95%, and normalization of kidney function was seen in 86% of participants. Hypertension corrected in 74%, and lipid abnormalities reversed in 66%.

Previous research has shown that only 2% of severely obese teenagers can lose weight and keep it off without surgery. “This study shows that at three years, almost 90% experienced clinically meaningful weight loss, and participants were in better health, with improved quality of life scores,” says Thomas Inge, MD, PhD, principal investigator and lead study author. He’s also the surgical director of the Surgical Weight Loss Program for Teens at Cincinnati Children’s Hospital Medical Center.

“The remission rates for medical conditions such as diabetes and hypertension are greater than those we see in many studies of adults who had long-standing obesity before bariatric surgery. It’s possible that earlier intervention could lead to better outcomes,” Inge says. “If sustained, the improvements seen in weight, blood sugar, kidney function, blood pressure, and lipid levels may translate into fewer strokes, heart attacks, and other disabilities later in life.”

Nutritional and other risks associated with surgery also were well documented. The study found that less than 5% of study participants had iron deficiency before surgery, but more than one-half had low iron stores three years after surgery, supporting the recommendation for monitoring of vitamin and iron supplementation in these patients. In addition, 13% of patients required additional abdominal surgery, most commonly gallbladder removal, during the three-year period.

“We’re also learning that once teens have crossed into these extremes of obesity, only 25% of them can achieve weights in the normal range after surgery, and over one-half of them remain severely obese even after surgery,” says Michael Helmrath, MD, a study coauthor and an adolescent bariatric surgeon at Cincinnati Children’s. “Timing of surgery may prove important.”

“Long-term studies like this one will help pediatricians and pediatric subspecialists have informed and balanced discussions with teens and their families about anticipated benefits and risks of bariatric surgery, especially important given that so many of us are now routinely caring for severely obese adolescents with significant health problems,” says Stavra Xanthakos, MD, a study coauthor and a pediatric gastroenterologist at Cincinnati Children’s.

Limitations of the study include the fact that it’s observational—not a randomized, controlled trial—and the majority of study participants are white females. However, this study population represents the patient group seeking surgery at the participating clinical centers. In addition, while participants were followed for three years postsurgery, it’s possible that some of the health improvements seen may diminish and other health risks could emerge later. Thus, longer follow-up of adolescents who have bariatric surgery is critical.

— Source: Cincinnati Children’s Hospital Medical Center