Vegan diet beats Mediterranean diet for weight loss, scientists find

A recent study found that a low-fat vegan diet is more effective for weight loss than a Mediterranean diet in overweight adults.

The four-month study, published in the journal Frontiers in Nutrition, randomly assigned 62 overweight adults to either a Mediterranean or a low-fat vegan diet for 16 weeks, then waited four weeks (wash-out period) before switching to the other diet. Results showed the low-fat vegan diet reduced the body’s overall acidity, a change associated with weight loss.

Key findings for health and weight loss:

• dietary acid load dropped significantly on the vegan diet, while no significant change was seen on the Mediterranean diet
• participants lost an average of six kilograms (13.2 pounds) on the vegan diet, with no significant weight change on the Mediterranean diet

Plant-based diets high in fruits, vegetables, pulses and whole grains are more alkaline, reducing inflammation and supporting a healthier metabolism, while animal products increase acid load and are linked to weight gain and chronic inflammation.

Switching to a low-fat vegan diet can lower your body’s dietary acid load and support significant weight loss, outperforming the Mediterranean diet for overweight individuals. The alkalising effect of plant-based foods such as leafy greens, berries, pulses and wholegrain foods, not only helps reduce body weight but also improves insulin sensitivity and may lower the risk of chronic diseases.

For best results:

• Focus on vegetables, fruits, pulses and wholegrains to maximise the alkalising and weight loss benefits.
• Limit acid-producing foods like meat, dairy, eggs and cheese to reduce dietary acid load and inflammation.

The authors concluded that: “The alkalising effect of a vegan diet may be an independent mechanism by which a vegan diet promotes weight loss”.

A low-fat vegan diet may be a powerful approach for lowering dietary acid load and achieving healthy weight loss in overweight adults.

Reference: Kahleova H, Maracine C, Himmelfarb J et al. 2025. Dietary acid load on the Mediterranean and a vegan diet: a secondary analysis of a randomized, crossover trial. Frontiers in Nutrition. 12, 1634215.