- Replacing animal protein with plant protein as part of a low fat vegan diet may support weight loss, according to recent research.
- Compared with the vegan diet, the Mediterranean diet did not lead to significant weight changes in the same trial.
- Experts advise that the Mediterranean diet may be better suited for people with high triglycerides, metabolic syndrome, or older adults at risk of muscle loss.
- A reduction in amino acids found in higher amounts in animal protein compared with plant protein resulted in greater weight loss, although researchers cannot yet confirm a direct relationship.
The type of protein, rather than the amount, could impact weight loss.
In general, a high protein diet can support weight loss by increasing satiety, which may lead to reduced food intake. However, a diet high in animal protein may
New research published in October in BMJ Nutrition, Prevention & Health explored whether plant protein could be more beneficial for weight loss than animal protein.
Secondary analysis of the trial found that overweight adults who replaced animal protein with plant protein as part of a low fat vegan diet lost weight, even though their total protein intake decreased.
When the same participants followed the Mediterranean diet, they did not experience any significant changes in protein intake or body weight.
Senior study author Hana Kahleova, MD, PhD, explained in the press release that “the (protein) source matters. Shifting the balance toward beans, lentils, tofu, and whole grains—and away from meat, dairy, and eggs—gave our participants a metabolic and a weight benefit they didn’t get by simply eating more vegetables on a Mediterranean-style diet.”
13 lbs weight loss with vegan diet
When following the low fat vegan diet for 16 weeks, participants experienced an average weight loss of around 13 pounds (lbs), or 6 kilograms (kg).
For the crossover trial, 62 adults followed either the vegan diet or the Mediterranean diet for 16 weeks. After four weeks without following either specific diet, they then switched to the other diet for another 16 weeks.
The vegan diet included:
- fruits
- vegetables
- grains
- legumes
It had a macronutrient composition target of:
- 75% carbohydrate
- 15% protein
- 10% fat
Participants avoided animal products, added fats, and cooking oils.
The vegan diet involved consuming a total of 46 grams (g) of protein per day, a reduction from 80 g at the start of the trial.
The total protein intake was reduced by 33.3 g per day on the vegan diet. Animal protein intake decreased by 47.7 g while plant protein rose by 14.4 g. None of these three measures changed significantly on the Mediterranean diet.
The researchers determined that replacing animal protein with plant protein in the low fat vegan diet was associated with weight loss in overweight adults.
However, they also highlight that they cannot confirm whether changes in protein alone led to weight loss, as changes in dietary fat, carbohydrates, and calorie density may also have played a role.
Medical News Today spoke with Mir Ali, MD, bariatric surgeon, bariatric medicine specialist and medical director of MemorialCare Surgical Weight Loss Center at Orange Coast Medical Center in Fountain Valley, CA, about these findings.
“While the magnitude of weight loss is notable, the findings align with a growing body of intervention trials comparing plant-based and Mediterranean frameworks. This shift is expected, given that eliminating animal products inherently reduces energy density and fat intake while increasing fiber,” said Ali, who was not involved in the study.
“The data originate from a randomized clinical crossover trial – the gold standard in nutritional intervention -strengthened by objective tracking via three-day food records evaluated by registered dietitians. However, because dietary shifts occurred concurrently, this is not a true comparison of animal versus plant protein, and further studies are needed,” he added.
Yoshua Quinones, board certified internist with Medical Offices of Manhattan and contributor to LabFinder.com, who was also not involved in the study, explained that “a low fat vegan diet can promote weight loss for many reasons. One reason is that veggies and grains provide fewer calories than animal protein. Fiber increases satiety, making you feel full.”
Quinones also told MNT that “
