A recent study published in Frontiers in Nutrition suggests a 16-week low-fat vegan diet may significantly outperform a Mediterranean diet in reducing dietary advanced glycation end-products (AGEs) and promoting weight loss.
AGEs are harmful compounds generally present in foods cooked at high temperatures, particularly in animal-derived rather than plant-based products. They have been linked to insulin resistance, inflammation, and oxidative stress, potentially contributing to a variety of chronic diseases, including diabetes and heart disease.
The new research is a secondary analysis of a 36-week crossover trial conducted by the Physicians Committee for Responsible Medicine in 2019, comparing the weight loss and cardiometabolic health outcomes of a low-fat vegan diet to a Mediterranean diet.
The results of the present study showed a significant reduction in dietary AGEs and body weight among participants on the low-fat vegan diet, while those on the Mediterranean diet experienced no significant changes.
The findings suggest that a low-fat vegan diet may have distinct advantages in the short term. However, further research is needed to establish whether it is truly more effective than a Mediterranean diet for long-term weight loss and overall health.
The original trial involved 62 adults with overweight or obesity aged 30 to 76, screened from a cohort of 506 individuals. Those already following a vegan or Mediterranean diet or with certain conditions or lifestyle factors that could influence the results were excluded.
Participants were randomly assigned to either a low-fat vegan diet or a Mediterranean diet for 16 weeks without calorie limitations.
The low-fat vegan diet focused solely on plant-based foods, including fruits, vegetables, grains, and legumes, and a daily supplement of 500 micrograms of vitamin B12. It excluded animal products and added fats.
The Mediterranean diet emphasized fruits, vegetables, legumes, and fish, along with 50 grams of extra-virgin olive oil daily. It discouraged red and processed meats, cream, butter, margarine, sugary drinks, pastries, and processed snacks.
After the initial 16 weeks, participants returned to their baseline (typical) diets for a 4-week “washout” before switching to the opposite diet for another 16 weeks.
Throughout the free-living study, participants were asked to maintain consistent physical activity and medications unless directed otherwise by their doctors. They attended weekly classes on their assigned diet for nutrition education, recipes, meal plans, and group support.
The researchers tracked participants’ body weight and composition, monitored their self-reported diet adherence, and had registered dietitians review participants’ 3-day diet records at four points during the trial.
In the secondary analysis, they analyzed dietary AGEs using the original trial’s self-reported diet records. Each food item was assigned an AGE score based on a published database of AGE content, along with estimations for less than 10% of foods not covered in the database.
The Physicians Committee’s analysis found significant differences in dietary AGEs and weight changes between a low-fat vegan diet and the Mediterranean diet.
The low-fat vegan diet resulted in a 73% reduction in dietary AGEs and an average weight loss of 13 pounds, while the Mediterranean diet showed no changes in AGE levels or body weight.
According to the study authors, the decrease in dietary AGEs on the low-fat vegan diet primarily resulted from eliminating meat (41%), minimizing added fats (27%), and avoiding dairy products (14%) — all known to be significant sources of dietary AGEs.
Most of the weight loss on a vegan diet came from losing body fat and visceral fat — ideal adjustments in body composition for promoting long-term health and reducing the risk of chronic diseases.
Additionally, the changes in dietary AGEs were associated with changes in body weight, and this connection stayed strong even after adjusting for overall calorie intake.
When considering the lack of effects from the Mediterranean diet, it’s important to take into account the characteristics of the study’s participants.
The study authors noted that their participants were a “health-conscious group” with a relatively low intake of saturated fat to begin with.
This might explain the lack of results from the Mediterranean diet, contrasting with previous studies that reported benefits of the Mediterranean diet when compared to other diets and in different populations, such as older adults and individuals with type 2 diabetes.
In support of the results, however, previous studies have reported that a low-fat vegan diet can reduce dietary AGEs in adults with overweight and people in postmenopause when compared to a typical diet.
Ultimately, this was a study directly comparing the Mediterranean diet with a low-fat vegan diet in reducing AGEs and the associated body weight outcomes, and the authors viewed it as “hypothesis-generating.”
This, alongside using self-reported dietary data and other potential study limitations, suggests further research is needed to confirm these novel findings.
AGEs are complex compounds that form in the bloodstream when sugars react with proteins, fats, or nucleic acids—a process known as glycation.
Notably, AGEs also originate from our food. In fact, most AGEs in the body derive from dietary sources and can accumulate to harmful levels with certain diet and lifestyle habits.
“[AGEs] are particularly abundant in animal products”, which are typically high in both protein and fat, “and foods cooked at high temperatures-especially when there is gristle or char created,” Thomas M. Holland, MD, MS, a physician-scientist and assistant professor at the Rush Institute for Healthy Aging, Rush University Medical Centre, who was not involved in the study, told Medical News Today.
In contrast, plant-based foods generally have lower AGE content due to their lower concentrations of proteins and fats and their typically lower cooking temperatures.
Holland explained how reducing dietary AGEs, particularly through adopting a low-fat vegan diet, could help promote weight loss:
“The low-fat vegan diet, which excludes animal products, reduces fat intake, and avoids dairy, leads to a significant decrease in dietary AGEs. This reduction is crucial because AGEs contribute to insulin resistance, which can hinder the body’s ability to manage glucose effectively, leading to weight gain. By reducing AGEs, the body can better regulate insulin, decrease inflammation, and improve overall metabolism, all of which contribute to weight loss.”
“The challenge with the low-fat vegan diet lies in its long-term sustainability,” said Holland. He noted that the “Mediterranean diet, on the other hand, is often praised for its balance and ease of integration into everyday life, which may make it a more sustainable option for many people.”
Still, he suggested that “although a vegan diet may initially seem restrictive,” especially to those transitioning from a typical Western diet, “it actually offers a wide variety of foods that are often underutilized.”
Eliza Whitaker, MS, RDN, a registered dietitian nutritionist at Dietitian Insights, who was not involved in the study, agreed and offered advice for those who want to adopt a low-fat vegan diet:
include a variety of fruits, non-starchy and starchy vegetables, beans, legumes, nuts, seeds, grains, and soy-based products.limit processed foods and read nutrition labels of prepared vegan foods to be mindful of fat intakesupplement with vitamin B12 and speak with a healthcare provider about whether to supplement iodine, vitamin D, and other essential vitamins and mineralsexplore new seasonings or flavors to enhance vegan foods and create similar flavor profiles and textures of animal productsbefore adopting a healthy, low-fat vegan diet for weight management, consult your physician or a registered dietitian to determine if this is the best approach to weight loss for you.
Both experts recommend adopting a gradual approach that aligns with what feels most sustainable for you. This could mean incorporating a few low-fat vegan meals into your weekly diet and stopping there or, if you prefer, eventually eliminating animal products entirely.
“Even if a vegan diet isn’t for you, this study provides further evidence to support reducing your consumption of animal-based foods and increasing consumption of plant-based foods,” Whitaker concluded.
