Vegan Diet Lowers Dietary Acid Load, and That May Help Explain Its Weight Loss

A low-fat vegan diet sharply cuts the acid load of what people eat, and the bigger the drop, the more weight they lose, according to a randomised trial published in Frontiers in Nutrition on June 25.

Researchers at the Physicians Committee for Responsible Medicine in Washington, DC put 62 overweight adults on either a Mediterranean diet or a low-fat vegan diet for 16 weeks, then swapped them over after a four-week break. Two standard measures of dietary acid load, PRAL and NEAP, fell by 25.8 and 27.1 points on the vegan diet and did not change on the Mediterranean diet. In both halves of the trial, falls in acid load went hand in hand with weight loss.

According to the press release, that link held even after accounting for calories, and body weight fell by 13.2 pounds (6kg) on the vegan diet, compared with no change on the Mediterranean diet.

"Eating acid-producing foods like meat, eggs, and dairy can increase the dietary acid load, or the amount of acids consumed, causing inflammation linked to weight gain," says lead author Dr Hana Kahleova. "But replacing animal products with plant-based foods like leafy greens, berries, and legumes can help promote weight loss and create a healthy gut microbiome."

The authors suggest this alkalizing effect may be one more way a vegan diet helps people lose weight. The top alkalizing foods are familiar ones: leafy greens, broccoli, berries, apples, lentils, chickpeas and beans.

It fits a long run of good news for plant-based eaters, from a whole food plant-based diet helping reverse type 2 diabetes to research showing plant protein is best for building muscle.

Pass the lentils!