Do Walnuts Cause Weight Gain?

By: Janelle Ringer, Loma Linda University Health News

Researchers at Loma Linda University Health found that walnuts can be incorporated into the daily diet of healthy older people without having a negative impact on weight gain or weight management.

The findings, published September 18, 2018 in the journal Nutrients, expand the knowledge of how nuts can affect independent-living, predominantly healthy elderly people.

The study’s lead author, Edward Bitok, assistant professor at Loma Linda University (LLU) School of Allied Health Professions, said a widespread fallacy exists that the fats in nut cause weight gain, and therefore could lead to issues such as obesity or other weight-related health issues such as heart disease or diabetes. The research, however, shows that nuts are a healthful snack.

“Because of their high energy content, many people have believed the misconception that nuts cause unwanted weight gain, and avoid them altogether,” Bitok said. “This study helps us understand more about good fats versus bad fats.”

The study was titled, “Effects of Long-Term Walnut Supplementation on Body Weight in Free-Living Elderly: Results of a Randomized Controlled Trial,” and was a sub-study of the Walnuts and Healthy Aging Study (WAHA), the first large study to test if walnuts play a part in healthy aging.

The WAHA study was a two-year trial supported by a grant from by the California Walnut Board and Commission, which tested how daily consumption of walnuts was associated with age-related cognitive decline and macular degeneration in seniors. “We wanted to provide research disproving the idea that the fats in nuts are unhealthy and cause weight gain,” Bitok said. “We conducted this study mainly to determine if subjects eating walnuts were at greater risk of weight gain compared to those who didn’t consume walnuts.”

Prior studies examining walnut consumption and body weight have focused on younger individuals and for shorter durations. “Research on long-term intake of walnuts and their effect on body weight in older adults has been lacking, and we wanted to close that gap,” Bitok said.

Bitok, who was a doctoral student at LLU School of Public Health at the time of the study, worked closely with co-author Joan Sabate, executive director of the Center for Nutrition, Healthy Lifestyle and Prevention Center at the School of Public Health, and the principal investigator for the WAHA study.

“Our hope was that seniors would be able to include nuts in their diet without concern for weight gain,” Sabate said. “Indeed, this was demonstrated in the study.”

The study looked at 307 participants between the ages of 63 and 79 who were healthy, free-living seniors residing within a 60-mile radius of Loma Linda University. The study began in October 2012 and ended in July 2016.